AA22-320A: Iranian Government-Sponsored APT Actors Compromise Federal Network, Deploy Crypto Miner, Credential Harvester

Cybersecurity
Original release date: November 16, 2022 Summary From mid-June through mid-
July 2022, CISA conducted an incident response engagement at a Federal
Civilian Executive Branch (FCEB) organization where CISA observed suspected
advanced persistent threat (APT) activity. In the course of incident response
activities, CISA determined that cyber threat actors exploited the Log4Shell
vulnerability in an unpatched VMware Horizon server, installed XMRig crypto
mining software, moved laterally to the domain controller (DC), compromised
credentials, and then implanted Ngrok reverse proxies on several hosts to
maintain persistence. CISA and the Federal Bureau of Investigation (FBI)
assess that the FCEB network was compromised by Iranian government-sponsored
APT actors. CISA and FBI are releasing this Cybersecurity Advisory (CSA)
providing the suspected Iranian government-sponsored actors’ tactics,
techniques, and procedures (TTPs) and indicators of compromise (IOCs) to help
network defenders detect and protect against related compromises. CISA and FBI
encourage all organizations with affected VMware systems that did not
immediately apply available patches or workarounds to assume compromise and
initiate threat hunting activities. If suspected initial access or compromise
is detected based on IOCs or TTPs described in this CSA, CISA and FBI
encourage organizations to assume lateral movement by threat actors,
investigate connected systems (including the DC), and audit privileged
accounts. All organizations, regardless of identified evidence of compromise,
should apply the recommendations in the Mitigations section of this CSA to
protect against similar malicious cyber activity. For more information on
Iranian government-sponsored Iranian malicious cyber activity, see CISA’s Iran
Cyber Threat Overview and Advisories webpage and FBI’s Iran Threats webpage.
Download the PDF version of this report: pdf, 528 kb . For a downloadable copy
of the Malware Analysis Report (MAR) accompanying this report, see: MAR
10387061-1.v1 . For a downloadable copy of IOCs, see: AA22-320A.stix, 1.55 mb
. Technical Details Note: This advisory uses the MITRE ATT&CK; for Enterprise
framework, version 11. See the MITRE ATT&CK; Tactics and Techniques section
for a table of the threat actors’ activity mapped to MITRE ATT&CK;® tactics
and techniques with corresponding mitigation and/or detection recommendations.
Overview In April 2022, CISA conducted retrospective analysis using
EINSTEIN—an FCEB-wide intrusion detection system (IDS) operated and monitored
by CISA—and identified suspected APT activity on an FCEB organization’s
network. CISA observed bi-directional traffic between the network and a known
malicious IP address associated with exploitation of the Log4Shell
vulnerability (CVE-2021-44228) in VMware Horizon servers. In coordination with
the FCEB organization, CISA initiated threat hunting incident response
activities; however, prior to deploying an incident response team, CISA
observed additional suspected APT activity. Specifically, CISA observed HTTPS
activity from IP address 51.89.181[.]64 to the organization’s VMware server.
Based on trusted third-party reporting, 51.89.181[.]64 is a Lightweight
Directory Access Protocol (LDAP) server associated with threat actors
exploiting Log4Shell. Following HTTPS activity, CISA observed a suspected LDAP
callback on port 443 to this IP address. CISA also observed a DNS query for
us‐nation‐ny[.]cf that resolved back to 51.89.181[.]64 when the victim server
was returning this Log4Shell LDAP callback to the actors’ server. CISA
assessed that this traffic indicated a confirmed compromise based on the
successful callback to the indicator and informed the organization of these
findings; the organization investigated the activity and found signs of
compromise. As trusted-third party reporting associated Log4Shell activity
from 51.89.181[.]64 with lateral movement and targeting of DCs, CISA suspected
the threat actors had moved laterally and compromised the organization’s DC.
From mid-June through mid-July 2022, CISA conducted an onsite incident
response engagement and determined that the organization was compromised as
early as February 2022, by likely Iranian government-sponsored APT actors who
installed XMRig crypto mining software. The threat actors also moved laterally
to the domain controller, compromised credentials, and implanted Ngrok reverse
proxies. Threat Actor Activity In February 2022, the threat actors exploited
Log4Shell [T1190 ] for initial access [TA0001 ] to the organization’s
unpatched VMware Horizon server. As part of their initial exploitation, CISA
observed a connection to known malicious IP address 182.54.217[.]2 lasting
17.6 seconds. The actors’ exploit payload ran the following PowerShell command
[T1059.001 ] that added an exclusion tool to Windows Defender [T1562.001 ]:
powershell try{Add-MpPreference -ExclusionPath ‘C:\’; Write-Host ‘added-
exclusion’} catch {Write-Host ‘adding-exclusion-failed’ }; powershell -enc
“$BASE64 encoded payload to download next stage and execute it” The exclusion
tool allowlisted the entire c:\drive , enabling threat actors to download
tools to the c:\drive without virus scans. The exploit payload then downloaded
mdeploy.text from 182.54.217[.]2/mdepoy.txt to C:\users\public\mde.ps1 [T1105
]. When executed, mde.ps1 downloaded file.zip from 182.54.217[.]2 and removed
mde.ps1 from the disk [T1070.004 ]. file.zip contained XMRig cryptocurrency
mining software and associated configuration files. WinRing0x64.sys – XMRig
Miner driver wuacltservice.exe – XMRig Miner config.json – XMRig miner
configuration RuntimeBroker.exe – Associated file. This file can create a
local user account [T1136.001 ] and tests for internet connectivity by pinging
8.8.8.8 [T1016.001 ]. The exploit payload created a Scheduled Task [T1053.005
] that executed RuntimeBroker.exe daily as SYSTEM . Note: By exploiting
Log4Shell, the actors gained access to a VMware service account with
administrator and system level access. The Scheduled Task was named
RuntimeBrokerService.exe to masquerade as a legitimate Windows task. See MAR
10387061-1.v1 for additional information, including IOCs, on these four files.
After obtaining initial access and installing XMRig on the VMWare Horizon
server, the actors used RDP [T1021.001 ] and the built-in Windows user account
DefaultAccount [T1078.001 ] to move laterally [TA0008 ] to a VMware VDI-KMS
host. Once the threat actor established themselves on the VDI-KMS host, CISA
observed the actors download around 30 megabytes of files from transfer[.]sh
server associated with 144.76.136[.]153 . The actors downloaded the following
tools: PsExec – a Microsoft signed tool for system administrators. Mimikatz –
a credential theft tool. Ngrok – a reverse proxy tool for proxying an internal
service out onto an Ngrok domain, which the user can then access at a randomly
generated subdomain at *.ngrok[.]io . CISA has observed this tool in use by
some commercial products for benign purposes; however, this process bypasses
typical firewall controls and may be a potentially unwanted application in
production environments. Ngrok is known to be used for malicious purposes.[1 ]
The threat actors then executed Mimikatz on VDI-KMS to harvest credentials and
created a rogue domain administrator account [T1136.002 ]. Using the newly
created account, the actors leveraged RDP to propagate to several hosts within
the network. Upon logging into each host, the actors manually disabled Windows
Defender via the Graphical User Interface (GUI) and implanted Ngrok
executables and configuration files. The threat actors were able to implant
Ngrok on multiple hosts to ensure Ngrok’s persistence should they lose access
to a machine during a routine reboot. The actors were able to proxy [T1090 ]
RDP sessions, which were only observable on the local network as outgoing
HTTPS port 443 connections to tunnel.us.ngrok[.]com and korgn.su.lennut[.]com
(the prior domain in reverse). It is possible, but was not observed, that the
threat actors configured a custom domain, or used other Ngrok tunnel domains,
wildcarded here as *.ngrok[.]com , *.ngrok[.]io , ngrok.*.tunnel[.]com , or
korgn.*.lennut[.]com . Once the threat actors established a deep foothold in
the network and moved laterally to the domain controller, they executed the
following PowerShell command on the Active Directory to obtain a list of all
machines attached to the domain [T1018 ]: Powershell.exe get-adcomputer
-filter * -properties * | select name,operatingsystem,ipv4address > The threat
actors also changed the password for the local administrator account [T1098 ]
on several hosts as a backup should the rogue domain administrator account get
detected and terminated. Additionally, the threat actor was observed
attempting to dump the Local Security Authority Subsystem Service (LSASS)
process [T1003.001 ] with task manager but this was stopped by additional
anti-virus the FCEB organization had installed. MITRE ATT&CK; TACTICS AND
TECHNIQUES See table 1 for all referenced threat actor tactics and techniques
in this advisory, as well as corresponding detection and/or mitigation
recommendations. For additional mitigations, see the Mitigations section.
Table 1: Cyber Threat Actors ATT&CK; Techniques for Enterprise Initial Access
Technique Title ID Use Recommendations Exploit Public-Facing Application T1190
The actors exploited Log4Shell for initial access to the organization’s VMware
Horizon server. Mitigation/Detection: Use a firewall or web-application
firewall and enable logging to prevent and detect potential Log4Shell
exploitation attempts [M1050 ]. Mitigation: Perform regular vulnerability
scanning to detect Log4J vulnerabilities and update Log4J software using
vendor provided patches [M1016 ],[M1051 ]. Execution Technique Title ID Use
Recommendation Command and Scripting Interpreter: PowerShell T1059.001 The
actors ran PowerShell commands that added an exclusion tool to Windows
Defender. The actors executed PowerShell on the AD to obtain a list of
machines on the domain. Mitigation: Disable or remove PowerShell for non-
administrative users [M1042 ],[M1026 ] or enable code-signing to execute only
signed scripts [M1045 ]. Mitigation: Employ anti-malware to automatically
detect and quarantine malicious scripts [M1049 ]. Persistence Technique Title
ID Use Recommendations Account Manipulation T1098 The actors changed the
password for the local administrator account on several hosts. Mitigation: Use
multifactor authentication for user and privileged accounts [M1032 ].
Detection: Monitor events for changes to account objects and/or permissions on
systems and the domain, such as event IDs 4738 , 4728 , and 4670 . Monitor for
modification of accounts in correlation with other suspicious activity [DS0002
]. Create Account: Local Account T1136.001 The actors’ malware can create
local user accounts. Mitigation: Configure access controls and firewalls to
limit access to domain controllers and systems used to create and manage
accounts. Detection: Monitor executed commands and arguments for actions that
are associated with local account creation, such as net user /add , useradd ,
and dscl -create [DS0017 ]. Detection: Enable logging for new user creation
[DS0002 ]. Create Account: Domain Account T1136.002 The actors used Mimikatz
to create a rogue domain administrator account. Mitigation: Configure access
controls and firewalls to limit access to domain controllers and systems used
to create and manage accounts. Detection: Enable logging for new user
creation, especially domain administrator accounts [DS0002 ]. Scheduled
Task/Job: Scheduled Task T1053.005 The actors’ exploit payload created
Scheduled Task RuntimeBrokerService.exe , which executed RuntimeBroker.exe
daily as SYSTEM . Mitigation: Configure settings for scheduled tasks to force
tasks to run under the context of the authenticated account instead of
allowing them to run as SYSTEM [M1028 ]. Detection: Monitor for newly
constructed processes and/or command-lines that execute from the svchost.exe
in Windows 10 and the Windows Task Scheduler taskeng.exe for older versions of
Windows [DS0009 ] Detection: Monitor for newly constructed scheduled jobs by
enabling the Microsoft-Windows-TaskScheduler/Operational setting within the
event logging service [DS0003 ]. Valid Accounts: Default Accounts T1078.001
The actors used built-in Windows user account DefaultAccount . Mitigation:
Change default usernames and passwords immediately after the installation and
before deployment to a production environment [M1027 ]. Detection: Develop
rules to monitor logon behavior across default accounts that have been
activated or logged into [DS0028 ]. Defense Evasion Technique Title ID Use
Recommendations Impair Defenses: Disable or Modify Tools T1562.001 The actors
added an exclusion tool to Windows Defender. The tool allowlisted the entire
c:\drive , enabling the actors to bypass virus scans for tools they downloaded
to the c:\drive . The actors manually disabled Windows Defender via the GUI.
Mitigation: Ensure proper user permissions are in place to prevent adversaries
from disabling or interfering with security services. [M1018 ]. Detection:
Monitor for changes made to Windows Registry keys and/or values related to
services and startup programs that correspond to security tools such as
HKLM:\SOFTWARE\Policies\Microsoft\Windows Defender [DS0024 ]. Detection:
Monitor for telemetry that provides context for modification or deletion of
information related to security software processes or services such as Windows
Defender definition files in Windows and System log files in Linux [DS0013 ].
Detection: Monitor processes for unexpected termination related to security
tools/services [DS0009 ]. Indicator Removal on Host: File Deletion T1070.004
The actors removed malicious file mde.ps1 from the dis. Detection: Monitor
executed commands and arguments for actions that could be utilized to unlink,
rename, or delete files [DS0017 ]. Detection: Monitor for unexpected deletion
of files from the system [DS0022 ]. Credential Access Technique Title ID Use
Recommendations OS Credential Dumping: LSASS Memory T1003.001 The actors were
observed trying to dump LSASS process. Mitigation: With Windows 10, Microsoft
implemented new protections called Credential Guard to protect the LSA secrets
that can be used to obtain credentials through forms of credential dumping
[M1043 ] Mitigation: On Windows 10, enable Attack Surface Reduction (ASR)
rules to secure LSASS and prevent credential stealing [M1040 ]. Mitigation:
Ensure that local administrator accounts have complex, unique passwords across
all systems on the network [M1027 ]. Detection: Monitor for unexpected
processes interacting with LSASS.exe . Common credential dumpers such as
Mimikatz access LSASS.exe by opening the process, locating the LSA secrets
key, and decrypting the sections in memory where credential details are
stored. [DS0009 ]. Detection: Monitor executed commands and arguments that may
attempt to access credential material stored in the process memory of the
LSASS [DS0017 ]. Credentials from Password Stores T1555 The actors used
Mimikatz to harvest credentials. Mitigation: Organizations may consider
weighing the risk of storing credentials in password stores and web browsers.
If system, software, or web browser credential disclosure is a significant
concern, technical controls, policy, and user training may be used to prevent
storage of credentials in improper locations [M1027 ]. Detection: Monitor for
processes being accessed that may search for common password storage locations
to obtain user credentials [DS0009 ]. Detection: Monitor executed commands and
arguments that may search for common password storage locations to obtain user
credentials [DS0017 ]. Discovery Technique Title ID Use Recommendations Remote
System Discovery T1018 The actors executed a PowerShell command on the AD to
obtain a list of all machines attached to the domain. Detection: Monitor
executed commands and arguments that may attempt to get a listing of other
systems by IP address, hostname, or other logical identifier on a network that
may be used for lateral movement [DS0017 ]. Detection: Monitor for newly
constructed network connections associated with pings/scans that may attempt
to get a listing of other systems by IP address, hostname, or other logical
identifier on a network that may be used for lateral movement [DS0029 ].
Detection: Monitor for newly executed processes that can be used to discover
remote systems, such as ping.exe and tracert.exe, especially when executed in
quick succession [DS0009 ]. System Network Configuration Discovery: Internet
Connection Discovery T1016.001 The actors’ malware tests for internet
connectivity by pinging 8.8.8.8 . Mitigation: Monitor executed commands,
arguments [DS0017 ] and executed processes (e.g., tracert or ping ) [DS0009 ]
that may check for internet connectivity on compromised systems. Lateral
Movement Technique Title ID Use Recommendations Remote Services: Remote
Desktop Protocol T1021.001 The actors used RDP to move laterally to multiple
hosts on the network. Mitigation: Use MFA for remote logins [M1032 ].
Mitigation: Disable the RDP service if it is unnecessary [M1042 ]. Mitigation:
Do not leave RDP accessible from the internet. Enable firewall rules to block
RDP traffic between network security zones within a network [M1030 ].
Mitigation: Consider removing the local Administrators group from the list of
groups allowed to log in through RDP [M1026 ]. Detection: Monitor for user
accounts logged into systems associated with RDP (ex: Windows EID 4624 Logon
Type 10). Other factors, such as access patterns (ex: multiple systems over a
relatively short period of time) and activity that occurs after a remote
login, may indicate suspicious or malicious behavior with RDP [DS0028 ].
Command and Control Technique Title ID Use Recommendations Proxy T1090 The
actors used Ngrok to proxy RDP connections and to perform command and control.
Mitigation: Traffic to known anonymity networks and C2 infrastructure can be
blocked through the use of network allow and block lists [M1037 ]. Detection:
Monitor and analyze traffic patterns and packet inspection associated to
protocol(s) that do not follow the expected protocol standards and traffic
flows (e.g., extraneous packets that do not belong to established flows,
gratuitous or anomalous traffic patterns, anomalous syntax, or structure)
[DS0029 ]. Ingress Tool Transfer T1105 The actors downloaded malware and
multiple tools to the network, including PsExec, Mimikatz, and Ngrok.
Mitigation: Employ anti-malware to automatically detect and quarantine
malicious scripts [M1049 ]. INCIDENT RESPONSE If suspected initial access or
compromise is detected based on IOCs or TTPs in this CSA, CISA encourages
organizations to assume lateral movement by threat actors and investigate
connected systems and the DC. CISA recommends organizations apply the
following steps before applying any mitigations, including patching.
Immediately isolate affected systems. Collect and review relevant logs, data,
and artifacts. Take a memory capture of the device(s) and a forensic image
capture for detailed analysis. Consider soliciting support from a third-party
incident response organization that can provide subject matter expertise to
ensure the actor is eradicated from the network and to avoid residual issues
that could enable follow-on exploitation. Report incidents to CISA via CISA’s
24/7 Operations Center (report@cisa.gov or 888-282-0870) or your local FBI
field office , or FBI’s 24/7 Cyber Watch (CyWatch) at (855) 292-3937 or by
e-mail at CyWatch@fbi.gov . Mitigations CISA and FBI recommend implementing
the mitigations below and in Table 1 to improve your organization’s
cybersecurity posture on the basis of threat actor behaviors. Install updated
builds to ensure affected VMware Horizon and UAG systems are updated to the
latest version . If updates or workarounds were not promptly applied following
VMware’s release of updates for Log4Shell in December 2021 , treat those
VMware Horizon systems as compromised. Follow the pro-active incident response
procedures outlined above prior to applying updates. If no compromise is
detected, apply these updates as soon as possible. See VMware Security
Advisory VMSA-2021-0028.13 and VMware Knowledge Base (KB) 87073 to determine
which VMware Horizon components are vulnerable. Note: Until the update is
fully implemented, consider removing vulnerable components from the internet
to limit the scope of traffic. While installing the updates, ensure network
perimeter access controls are as restrictive as possible. If upgrading is not
immediately feasible, see KB87073 and KB87092 for vendor-provided temporary
workarounds. Implement temporary solutions using an account with
administrative privileges. Note that these temporary solutions should not be
treated as permanent fixes; vulnerable components should be upgraded to the
latest build as soon as possible. Prior to implementing any temporary
solution, ensure appropriate backups have been completed. Verify successful
implementation of mitigations by executing the vendor supplied script
Horizon_Windows_Log4j_Mitigations.zip without parameters to ensure that no
vulnerabilities remain. See KB87073 for details. Keep all software up to date
and prioritize patching known exploited vulnerabilities (KEVs) . Minimize the
internet-facing attack surface by hosting essential services on a segregated
DMZ, ensuring strict network perimeter access controls, and not hosting
internet-facing services that are not essential to business operations. Where
possible, implement regularly updated web application firewalls (WAF) in front
of public-facing services. WAFs can protect against web-based exploitation
using signatures and heuristics that are likely to block or alert on malicious
traffic. Use best practices for identity and access management (IAM) by
implementing phishing resistant multifactor authentication (MFA) , enforcing
use of strong passwords, regularly auditing administrator accounts and
permissions, and limiting user access through the principle of least
privilege. Disable inactive accounts uniformly across the AD, MFA systems,
etc. If using Windows 10 version 1607 or Windows Server 2016 or later, monitor
or disable Windows DefaultAccount , also known as the Default System Managed
Account (DSMA). Audit domain controllers to log successful Kerberos Ticket
Granting Service (TGS) requests and ensure the events are monitored for
anomalous activity. Secure accounts. Enforce the principle of least privilege.
Administrator accounts should have the minimum permission necessary to
complete their tasks. Ensure there are unique and distinct administrative
accounts for each set of administrative tasks. Create non-privileged accounts
for privileged users and ensure they use the non-privileged accounts for all
non-privileged access (e.g., web browsing, email access). Create a deny list
of known compromised credentials and prevent users from using known-
compromised passwords. Secure credentials by restricting where accounts and
credentials can be used and by using local device credential protection
features. Use virtualizing solutions on modern hardware and software to ensure
credentials are securely stored. Ensure storage of clear text passwords in
LSASS memory is disabled. Note: For Windows 8, this is enabled by default. For
more information see Microsoft Security Advisory Update to Improve Credentials
Protection and Management . Consider disabling or limiting NTLM and WDigest
Authentication. Implement Credential Guard for Windows 10 and Server 2016
(refer to Microsoft: Manage Windows Defender Credential Guard for more
information). For Windows Server 2012R2, enable Protected Process Light for
Local Security Authority (LSA). Minimize the AD attack surface to reduce
malicious ticket-granting activity. Malicious activity such as “Kerberoasting”
takes advantage of Kerberos’ TGS and can be used to obtain hashed credentials
that threat actors attempt to crack. VALIDATE SECURITY CONTROLS In addition to
applying mitigations, CISA and FBI recommend exercising, testing, and
validating your organization’s security program against the threat behaviors
mapped to the MITRE ATT&CK; for Enterprise framework in this advisory. CISA
and FBI recommend testing your existing security controls inventory to assess
how they perform against the ATT&CK; techniques described in this advisory. To
get started: Select an ATT&CK; technique described in this advisory (see table
1). Align your security technologies against the technique. Test your
technologies against the technique. Analyze your detection and prevention
technologies performance. Repeat the process for all security technologies to
obtain a set of comprehensive performance data. Tune your security program,
including people, processes, and technologies, based on the data generated by
this process. CISA and FBI recommend continually testing your security
program, at scale, in a production environment to ensure optimal performance
against the MITRE ATT&CK; techniques identified in this advisory. References
[1] MITRE ATT&CK; Version 11: Software – Ngrok Revisions Initial Version:
November 16, 2022 This product is provided subject to this Notification and
this Privacy & Use policy.Original release date: November 16, 2022 Summary From mid-June through mid-
July 2022, CISA conducted an incident response engagement at a Federal
Civilian Executive Branch (FCEB) organization where CISA observed suspected
advanced persistent threat (APT) activity. In the course of incident response
activities, CISA determined that cyber threat actors exploited the Log4Shell
vulnerability in an unpatched VMware Horizon server, installed XMRig crypto
mining software, moved laterally to the domain controller (DC), compromised
credentials, and then implanted Ngrok reverse proxies on several hosts to
maintain persistence. CISA and the Federal Bureau of Investigation (FBI)
assess that the FCEB network was compromised by Iranian government-sponsored
APT actors. CISA and FBI are releasing this Cybersecurity Advisory (CSA)
providing the suspected Iranian government-sponsored actors’ tactics,
techniques, and procedures (TTPs) and indicators of compromise (IOCs) to help
network defenders detect and protect against related compromises. CISA and FBI
encourage all organizations with affected VMware systems that did not
immediately apply available patches or workarounds to assume compromise and
initiate threat hunting activities. If suspected initial access or compromise
is detected based on IOCs or TTPs described in this CSA, CISA and FBI
encourage organizations to assume lateral movement by threat actors,
investigate connected systems (including the DC), and audit privileged
accounts. All organizations, regardless of identified evidence of compromise,
should apply the recommendations in the Mitigations section of this CSA to
protect against similar malicious cyber activity. For more information on
Iranian government-sponsored Iranian malicious cyber activity, see CISA’s Iran
Cyber Threat Overview and Advisories webpage and FBI’s Iran Threats webpage.
Download the PDF version of this report: pdf, 528 kb . For a downloadable copy
of the Malware Analysis Report (MAR) accompanying this report, see: MAR
10387061-1.v1 . For a downloadable copy of IOCs, see: AA22-320A.stix, 1.55 mb
. Technical Details Note: This advisory uses the MITRE ATT&CK; for Enterprise
framework, version 11. See the MITRE ATT&CK; Tactics and Techniques section
for a table of the threat actors’ activity mapped to MITRE ATT&CK;® tactics
and techniques with corresponding mitigation and/or detection recommendations.
Overview In April 2022, CISA conducted retrospective analysis using
EINSTEIN—an FCEB-wide intrusion detection system (IDS) operated and monitored
by CISA—and identified suspected APT activity on an FCEB organization’s
network. CISA observed bi-directional traffic between the network and a known
malicious IP address associated with exploitation of the Log4Shell
vulnerability (CVE-2021-44228) in VMware Horizon servers. In coordination with
the FCEB organization, CISA initiated threat hunting incident response
activities; however, prior to deploying an incident response team, CISA
observed additional suspected APT activity. Specifically, CISA observed HTTPS
activity from IP address 51.89.181[.]64 to the organization’s VMware server.
Based on trusted third-party reporting, 51.89.181[.]64 is a Lightweight
Directory Access Protocol (LDAP) server associated with threat actors
exploiting Log4Shell. Following HTTPS activity, CISA observed a suspected LDAP
callback on port 443 to this IP address. CISA also observed a DNS query for
us‐nation‐ny[.]cf that resolved back to 51.89.181[.]64 when the victim server
was returning this Log4Shell LDAP callback to the actors’ server. CISA
assessed that this traffic indicated a confirmed compromise based on the
successful callback to the indicator and informed the organization of these
findings; the organization investigated the activity and found signs of
compromise. As trusted-third party reporting associated Log4Shell activity
from 51.89.181[.]64 with lateral movement and targeting of DCs, CISA suspected
the threat actors had moved laterally and compromised the organization’s DC.
From mid-June through mid-July 2022, CISA conducted an onsite incident
response engagement and determined that the organization was compromised as
early as February 2022, by likely Iranian government-sponsored APT actors who
installed XMRig crypto mining software. The threat actors also moved laterally
to the domain controller, compromised credentials, and implanted Ngrok reverse
proxies. Threat Actor Activity In February 2022, the threat actors exploited
Log4Shell [T1190 ] for initial access [TA0001 ] to the organization’s
unpatched VMware Horizon server. As part of their initial exploitation, CISA
observed a connection to known malicious IP address 182.54.217[.]2 lasting
17.6 seconds. The actors’ exploit payload ran the following PowerShell command
[T1059.001 ] that added an exclusion tool to Windows Defender [T1562.001 ]:
powershell try{Add-MpPreference -ExclusionPath ‘C:\’; Write-Host ‘added-
exclusion’} catch {Write-Host ‘adding-exclusion-failed’ }; powershell -enc
“$BASE64 encoded payload to download next stage and execute it” The exclusion
tool allowlisted the entire c:\drive , enabling threat actors to download
tools to the c:\drive without virus scans. The exploit payload then downloaded
mdeploy.text from 182.54.217[.]2/mdepoy.txt to C:\users\public\mde.ps1 [T1105
]. When executed, mde.ps1 downloaded file.zip from 182.54.217[.]2 and removed
mde.ps1 from the disk [T1070.004 ]. file.zip contained XMRig cryptocurrency
mining software and associated configuration files. WinRing0x64.sys – XMRig
Miner driver wuacltservice.exe – XMRig Miner config.json – XMRig miner
configuration RuntimeBroker.exe – Associated file. This file can create a
local user account [T1136.001 ] and tests for internet connectivity by pinging
8.8.8.8 [T1016.001 ]. The exploit payload created a Scheduled Task [T1053.005
] that executed RuntimeBroker.exe daily as SYSTEM . Note: By exploiting
Log4Shell, the actors gained access to a VMware service account with
administrator and system level access. The Scheduled Task was named
RuntimeBrokerService.exe to masquerade as a legitimate Windows task. See MAR
10387061-1.v1 for additional information, including IOCs, on these four files.
After obtaining initial access and installing XMRig on the VMWare Horizon
server, the actors used RDP [T1021.001 ] and the built-in Windows user account
DefaultAccount [T1078.001 ] to move laterally [TA0008 ] to a VMware VDI-KMS
host. Once the threat actor established themselves on the VDI-KMS host, CISA
observed the actors download around 30 megabytes of files from transfer[.]sh
server associated with 144.76.136[.]153 . The actors downloaded the following
tools: PsExec – a Microsoft signed tool for system administrators. Mimikatz –
a credential theft tool. Ngrok – a reverse proxy tool for proxying an internal
service out onto an Ngrok domain, which the user can then access at a randomly
generated subdomain at *.ngrok[.]io . CISA has observed this tool in use by
some commercial products for benign purposes; however, this process bypasses
typical firewall controls and may be a potentially unwanted application in
production environments. Ngrok is known to be used for malicious purposes.[1 ]
The threat actors then executed Mimikatz on VDI-KMS to harvest credentials and
created a rogue domain administrator account [T1136.002 ]. Using the newly
created account, the actors leveraged RDP to propagate to several hosts within
the network. Upon logging into each host, the actors manually disabled Windows
Defender via the Graphical User Interface (GUI) and implanted Ngrok
executables and configuration files. The threat actors were able to implant
Ngrok on multiple hosts to ensure Ngrok’s persistence should they lose access
to a machine during a routine reboot. The actors were able to proxy [T1090 ]
RDP sessions, which were only observable on the local network as outgoing
HTTPS port 443 connections to tunnel.us.ngrok[.]com and korgn.su.lennut[.]com
(the prior domain in reverse). It is possible, but was not observed, that the
threat actors configured a custom domain, or used other Ngrok tunnel domains,
wildcarded here as *.ngrok[.]com , *.ngrok[.]io , ngrok.*.tunnel[.]com , or
korgn.*.lennut[.]com . Once the threat actors established a deep foothold in
the network and moved laterally to the domain controller, they executed the
following PowerShell command on the Active Directory to obtain a list of all
machines attached to the domain [T1018 ]: Powershell.exe get-adcomputer
-filter * -properties * | select name,operatingsystem,ipv4address > The threat
actors also changed the password for the local administrator account [T1098 ]
on several hosts as a backup should the rogue domain administrator account get
detected and terminated. Additionally, the threat actor was observed
attempting to dump the Local Security Authority Subsystem Service (LSASS)
process [T1003.001 ] with task manager but this was stopped by additional
anti-virus the FCEB organization had installed. MITRE ATT&CK; TACTICS AND
TECHNIQUES See table 1 for all referenced threat actor tactics and techniques
in this advisory, as well as corresponding detection and/or mitigation
recommendations. For additional mitigations, see the Mitigations section.
Table 1: Cyber Threat Actors ATT&CK; Techniques for Enterprise Initial Access
Technique Title ID Use Recommendations Exploit Public-Facing Application T1190
The actors exploited Log4Shell for initial access to the organization’s VMware
Horizon server. Mitigation/Detection: Use a firewall or web-application
firewall and enable logging to prevent and detect potential Log4Shell
exploitation attempts [M1050 ]. Mitigation: Perform regular vulnerability
scanning to detect Log4J vulnerabilities and update Log4J software using
vendor provided patches [M1016 ],[M1051 ]. Execution Technique Title ID Use
Recommendation Command and Scripting Interpreter: PowerShell T1059.001 The
actors ran PowerShell commands that added an exclusion tool to Windows
Defender. The actors executed PowerShell on the AD to obtain a list of
machines on the domain. Mitigation: Disable or remove PowerShell for non-
administrative users [M1042 ],[M1026 ] or enable code-signing to execute only
signed scripts [M1045 ]. Mitigation: Employ anti-malware to automatically
detect and quarantine malicious scripts [M1049 ]. Persistence Technique Title
ID Use Recommendations Account Manipulation T1098 The actors changed the
password for the local administrator account on several hosts. Mitigation: Use
multifactor authentication for user and privileged accounts [M1032 ].
Detection: Monitor events for changes to account objects and/or permissions on
systems and the domain, such as event IDs 4738 , 4728 , and 4670 . Monitor for
modification of accounts in correlation with other suspicious activity [DS0002
]. Create Account: Local Account T1136.001 The actors’ malware can create
local user accounts. Mitigation: Configure access controls and firewalls to
limit access to domain controllers and systems used to create and manage
accounts. Detection: Monitor executed commands and arguments for actions that
are associated with local account creation, such as net user /add , useradd ,
and dscl -create [DS0017 ]. Detection: Enable logging for new user creation
[DS0002 ]. Create Account: Domain Account T1136.002 The actors used Mimikatz
to create a rogue domain administrator account. Mitigation: Configure access
controls and firewalls to limit access to domain controllers and systems used
to create and manage accounts. Detection: Enable logging for new user
creation, especially domain administrator accounts [DS0002 ]. Scheduled
Task/Job: Scheduled Task T1053.005 The actors’ exploit payload created
Scheduled Task RuntimeBrokerService.exe , which executed RuntimeBroker.exe
daily as SYSTEM . Mitigation: Configure settings for scheduled tasks to force
tasks to run under the context of the authenticated account instead of
allowing them to run as SYSTEM [M1028 ]. Detection: Monitor for newly
constructed processes and/or command-lines that execute from the svchost.exe
in Windows 10 and the Windows Task Scheduler taskeng.exe for older versions of
Windows [DS0009 ] Detection: Monitor for newly constructed scheduled jobs by
enabling the Microsoft-Windows-TaskScheduler/Operational setting within the
event logging service [DS0003 ]. Valid Accounts: Default Accounts T1078.001
The actors used built-in Windows user account DefaultAccount . Mitigation:
Change default usernames and passwords immediately after the installation and
before deployment to a production environment [M1027 ]. Detection: Develop
rules to monitor logon behavior across default accounts that have been
activated or logged into [DS0028 ]. Defense Evasion Technique Title ID Use
Recommendations Impair Defenses: Disable or Modify Tools T1562.001 The actors
added an exclusion tool to Windows Defender. The tool allowlisted the entire
c:\drive , enabling the actors to bypass virus scans for tools they downloaded
to the c:\drive . The actors manually disabled Windows Defender via the GUI.
Mitigation: Ensure proper user permissions are in place to prevent adversaries
from disabling or interfering with security services. [M1018 ]. Detection:
Monitor for changes made to Windows Registry keys and/or values related to
services and startup programs that correspond to security tools such as
HKLM:\SOFTWARE\Policies\Microsoft\Windows Defender [DS0024 ]. Detection:
Monitor for telemetry that provides context for modification or deletion of
information related to security software processes or services such as Windows
Defender definition files in Windows and System log files in Linux [DS0013 ].
Detection: Monitor processes for unexpected termination related to security
tools/services [DS0009 ]. Indicator Removal on Host: File Deletion T1070.004
The actors removed malicious file mde.ps1 from the dis. Detection: Monitor
executed commands and arguments for actions that could be utilized to unlink,
rename, or delete files [DS0017 ]. Detection: Monitor for unexpected deletion
of files from the system [DS0022 ]. Credential Access Technique Title ID Use
Recommendations OS Credential Dumping: LSASS Memory T1003.001 The actors were
observed trying to dump LSASS process. Mitigation: With Windows 10, Microsoft
implemented new protections called Credential Guard to protect the LSA secrets
that can be used to obtain credentials through forms of credential dumping
[M1043 ] Mitigation: On Windows 10, enable Attack Surface Reduction (ASR)
rules to secure LSASS and prevent credential stealing [M1040 ]. Mitigation:
Ensure that local administrator accounts have complex, unique passwords across
all systems on the network [M1027 ]. Detection: Monitor for unexpected
processes interacting with LSASS.exe . Common credential dumpers such as
Mimikatz access LSASS.exe by opening the process, locating the LSA secrets
key, and decrypting the sections in memory where credential details are
stored. [DS0009 ]. Detection: Monitor executed commands and arguments that may
attempt to access credential material stored in the process memory of the
LSASS [DS0017 ]. Credentials from Password Stores T1555 The actors used
Mimikatz to harvest credentials. Mitigation: Organizations may consider
weighing the risk of storing credentials in password stores and web browsers.
If system, software, or web browser credential disclosure is a significant
concern, technical controls, policy, and user training may be used to prevent
storage of credentials in improper locations [M1027 ]. Detection: Monitor for
processes being accessed that may search for common password storage locations
to obtain user credentials [DS0009 ]. Detection: Monitor executed commands and
arguments that may search for common password storage locations to obtain user
credentials [DS0017 ]. Discovery Technique Title ID Use Recommendations Remote
System Discovery T1018 The actors executed a PowerShell command on the AD to
obtain a list of all machines attached to the domain. Detection: Monitor
executed commands and arguments that may attempt to get a listing of other
systems by IP address, hostname, or other logical identifier on a network that
may be used for lateral movement [DS0017 ]. Detection: Monitor for newly
constructed network connections associated with pings/scans that may attempt
to get a listing of other systems by IP address, hostname, or other logical
identifier on a network that may be used for lateral movement [DS0029 ].
Detection: Monitor for newly executed processes that can be used to discover
remote systems, such as ping.exe and tracert.exe, especially when executed in
quick succession [DS0009 ]. System Network Configuration Discovery: Internet
Connection Discovery T1016.001 The actors’ malware tests for internet
connectivity by pinging 8.8.8.8 . Mitigation: Monitor executed commands,
arguments [DS0017 ] and executed processes (e.g., tracert or ping ) [DS0009 ]
that may check for internet connectivity on compromised systems. Lateral
Movement Technique Title ID Use Recommendations Remote Services: Remote
Desktop Protocol T1021.001 The actors used RDP to move laterally to multiple
hosts on the network. Mitigation: Use MFA for remote logins [M1032 ].
Mitigation: Disable the RDP service if it is unnecessary [M1042 ]. Mitigation:
Do not leave RDP accessible from the internet. Enable firewall rules to block
RDP traffic between network security zones within a network [M1030 ].
Mitigation: Consider removing the local Administrators group from the list of
groups allowed to log in through RDP [M1026 ]. Detection: Monitor for user
accounts logged into systems associated with RDP (ex: Windows EID 4624 Logon
Type 10). Other factors, such as access patterns (ex: multiple systems over a
relatively short period of time) and activity that occurs after a remote
login, may indicate suspicious or malicious behavior with RDP [DS0028 ].
Command and Control Technique Title ID Use Recommendations Proxy T1090 The
actors used Ngrok to proxy RDP connections and to perform command and control.
Mitigation: Traffic to known anonymity networks and C2 infrastructure can be
blocked through the use of network allow and block lists [M1037 ]. Detection:
Monitor and analyze traffic patterns and packet inspection associated to
protocol(s) that do not follow the expected protocol standards and traffic
flows (e.g., extraneous packets that do not belong to established flows,
gratuitous or anomalous traffic patterns, anomalous syntax, or structure)
[DS0029 ]. Ingress Tool Transfer T1105 The actors downloaded malware and
multiple tools to the network, including PsExec, Mimikatz, and Ngrok.
Mitigation: Employ anti-malware to automatically detect and quarantine
malicious scripts [M1049 ]. INCIDENT RESPONSE If suspected initial access or
compromise is detected based on IOCs or TTPs in this CSA, CISA encourages
organizations to assume lateral movement by threat actors and investigate
connected systems and the DC. CISA recommends organizations apply the
following steps before applying any mitigations, including patching.
Immediately isolate affected systems. Collect and review relevant logs, data,
and artifacts. Take a memory capture of the device(s) and a forensic image
capture for detailed analysis. Consider soliciting support from a third-party
incident response organization that can provide subject matter expertise to
ensure the actor is eradicated from the network and to avoid residual issues
that could enable follow-on exploitation. Report incidents to CISA via CISA’s
24/7 Operations Center (report@cisa.gov or 888-282-0870) or your local FBI
field office , or FBI’s 24/7 Cyber Watch (CyWatch) at (855) 292-3937 or by
e-mail at CyWatch@fbi.gov . Mitigations CISA and FBI recommend implementing
the mitigations below and in Table 1 to improve your organization’s
cybersecurity posture on the basis of threat actor behaviors. Install updated
builds to ensure affected VMware Horizon and UAG systems are updated to the
latest version . If updates or workarounds were not promptly applied following
VMware’s release of updates for Log4Shell in December 2021 , treat those
VMware Horizon systems as compromised. Follow the pro-active incident response
procedures outlined above prior to applying updates. If no compromise is
detected, apply these updates as soon as possible. See VMware Security
Advisory VMSA-2021-0028.13 and VMware Knowledge Base (KB) 87073 to determine
which VMware Horizon components are vulnerable. Note: Until the update is
fully implemented, consider removing vulnerable components from the internet
to limit the scope of traffic. While installing the updates, ensure network
perimeter access controls are as restrictive as possible. If upgrading is not
immediately feasible, see KB87073 and KB87092 for vendor-provided temporary
workarounds. Implement temporary solutions using an account with
administrative privileges. Note that these temporary solutions should not be
treated as permanent fixes; vulnerable components should be upgraded to the
latest build as soon as possible. Prior to implementing any temporary
solution, ensure appropriate backups have been completed. Verify successful
implementation of mitigations by executing the vendor supplied script
Horizon_Windows_Log4j_Mitigations.zip without parameters to ensure that no
vulnerabilities remain. See KB87073 for details. Keep all software up to date
and prioritize patching known exploited vulnerabilities (KEVs) . Minimize the
internet-facing attack surface by hosting essential services on a segregated
DMZ, ensuring strict network perimeter access controls, and not hosting
internet-facing services that are not essential to business operations. Where
possible, implement regularly updated web application firewalls (WAF) in front
of public-facing services. WAFs can protect against web-based exploitation
using signatures and heuristics that are likely to block or alert on malicious
traffic. Use best practices for identity and access management (IAM) by
implementing phishing resistant multifactor authentication (MFA) , enforcing
use of strong passwords, regularly auditing administrator accounts and
permissions, and limiting user access through the principle of least
privilege. Disable inactive accounts uniformly across the AD, MFA systems,
etc. If using Windows 10 version 1607 or Windows Server 2016 or later, monitor
or disable Windows DefaultAccount , also known as the Default System Managed
Account (DSMA). Audit domain controllers to log successful Kerberos Ticket
Granting Service (TGS) requests and ensure the events are monitored for
anomalous activity. Secure accounts. Enforce the principle of least privilege.
Administrator accounts should have the minimum permission necessary to
complete their tasks. Ensure there are unique and distinct administrative
accounts for each set of administrative tasks. Create non-privileged accounts
for privileged users and ensure they use the non-privileged accounts for all
non-privileged access (e.g., web browsing, email access). Create a deny list
of known compromised credentials and prevent users from using known-
compromised passwords. Secure credentials by restricting where accounts and
credentials can be used and by using local device credential protection
features. Use virtualizing solutions on modern hardware and software to ensure
credentials are securely stored. Ensure storage of clear text passwords in
LSASS memory is disabled. Note: For Windows 8, this is enabled by default. For
more information see Microsoft Security Advisory Update to Improve Credentials
Protection and Management . Consider disabling or limiting NTLM and WDigest
Authentication. Implement Credential Guard for Windows 10 and Server 2016
(refer to Microsoft: Manage Windows Defender Credential Guard for more
information). For Windows Server 2012R2, enable Protected Process Light for
Local Security Authority (LSA). Minimize the AD attack surface to reduce
malicious ticket-granting activity. Malicious activity such as “Kerberoasting”
takes advantage of Kerberos’ TGS and can be used to obtain hashed credentials
that threat actors attempt to crack. VALIDATE SECURITY CONTROLS In addition to
applying mitigations, CISA and FBI recommend exercising, testing, and
validating your organization’s security program against the threat behaviors
mapped to the MITRE ATT&CK; for Enterprise framework in this advisory. CISA
and FBI recommend testing your existing security controls inventory to assess
how they perform against the ATT&CK; techniques described in this advisory. To
get started: Select an ATT&CK; technique described in this advisory (see table
1). Align your security technologies against the technique. Test your
technologies against the technique. Analyze your detection and prevention
technologies performance. Repeat the process for all security technologies to
obtain a set of comprehensive performance data. Tune your security program,
including people, processes, and technologies, based on the data generated by
this process. CISA and FBI recommend continually testing your security
program, at scale, in a production environment to ensure optimal performance
against the MITRE ATT&CK; techniques identified in this advisory. References
[1] MITRE ATT&CK; Version 11: Software – Ngrok Revisions Initial Version:
November 16, 2022 This product is provided subject to this Notification and
this Privacy & Use policy. November 16 2022 09:04:03
AA22-320A: Iranian Government-Sponsored APT Actors Compromise Federal Network, Deploy Crypto Miner, Credential Harvester