AA22-228A: Threat Actors Exploiting Multiple CVEs Against Zimbra Collaboration Suite

Original release date: August 16, 2022 | Last revised: August 22, 2022 Summary
Actions for ZCS administrators to take today to mitigate malicious cyber
activity: • Patch all systems and prioritize patching known exploited
vulnerabilities. • Deploy detection signatures and hunt for indicators of
compromise (IOCs). • If ZCS was compromised, remediate malicious activity. The
Cybersecurity and Infrastructure Security Agency (CISA ) and the Multi-State
Information Sharing & Analysis Center (MS-ISAC ) are publishing this joint
Cybersecurity Advisory (CSA) in response to active exploitation of multiple
Common Vulnerabilities and Exposures (CVEs) against Zimbra Collaboration Suite
(ZCS), an enterprise cloud-hosted collaboration software and email platform.
CVEs currently being exploited against ZCS include: CVE-2022-24682
CVE-2022-27924 CVE-2022-27925 chained with CVE-2022-37042 CVE-2022-30333 Cyber
threat actors may be targeting unpatched ZCS instances in both government and
private sector networks. CISA and the MS-ISAC strongly urge users and
administrators to apply the guidance in the Recommendations section of this
CSA to help secure their organization’s systems against malicious cyber
activity. CISA and the MS-ISAC encourage organizations who did not immediately
update their ZCS instances upon patch release, or whose ZCS instances were
exposed to the internet, to assume compromise and hunt for malicious activity
using the third-party detection signatures in the Detection Methods section of
this CSA. Organizations that detect potential compromise should apply the
steps in the Incident Response section of this CSA. Update August 22, 2022:
This CSA has been updated with additional detection signatures. Update End
Download the PDF version of this report: pdf, 355 kb Technical Details
CVE-2022-27924 CVE-2022-27924 is a high-severity vulnerability enabling an
unauthenticated malicious actor to inject arbitrary memcache commands into a
targeted ZCS instance and cause an overwrite of arbitrary cached entries. The
actor can then steal ZCS email account credentials in cleartext form without
any user interaction. With valid email account credentials in an organization
not enforcing multifactor authentication (MFA), a malicious actor can use
spear phishing, social engineering, and business email compromise (BEC)
attacks against the compromised organization. Additionally, malicious actors
could use the valid account credentials to open webshells and maintain
persistent access. On March 11, 2022, researchers from SonarSource announced
the discovery of this ZCS vulnerability. Zimbra issued fixes for releases
8.8.15 and 9.0 on May 10, 2022. In June 2022, SonarSource publicly released
proof-of-concept (POC) exploits for this vulnerability.[1 ][2 ] Based on
evidence of active exploitation, CISA added this vulnerability to the Known
Exploited Vulnerabilities Catalog on August 4, 2022. Due to the POC and ease
of exploitation, CISA and the MS-ISAC expect to see widespread exploitation of
unpatched ZCS instances in government and private networks. CVE-2022-27925 and
CVE-2022-37042 CVE-2022-27925 is a high severity vulnerability in ZCS releases
8.8.15 and 9.0 that have mboximport functionality to receive a ZIP archive and
extract files from it. An authenticated user has the ability to upload
arbitrary files to the system thereby leading to directory traversal.[3 ] On
August 10, 2022, researchers from Volexity reported widespread
exploitation—against over 1,000 ZCS instances—of CVE-2022-27925 in conjunction
with CVE-2022-37042.[4 ] CISA added both CVEs to the Known Exploited
Vulnerabilities Catalog on August 11, 2022. CVE-2022-37042 is an
authentication bypass vulnerability that affects ZCS releases 8.8.15 and 9.0.
CVE-2022-37042 could allow an unauthenticated malicious actor access to a
vulnerable ZCS instance. According to Zimbra, CVE-2022-37042 is found in the
MailboxImportServlet function.[5 ][6 ] Zimbra issued fixes in late July 2022.
CVE-2022-30333 CVE-2022-30333 is a high-severity directory traversal
vulnerability in RARLAB UnRAR on Linux and UNIX allowing a malicious actor to
write to files during an extract (unpack) operation. A malicious actor can
exploit CVE-2022-30333 against a ZCS server by sending an email with a
malicious RAR file. Upon email receipt, the ZCS server would automatically
extract the RAR file to check for spam or malware.[7 ] Any ZCS instance with
unrar installed is vulnerable to CVE-2022-30333. Researchers from SonarSource
shared details about this vulnerability in June 2022.[8 ] Zimbra made
configuration changes to use the 7zip program instead of unrar .[9 ] CISA
added CVE-2022-3033 to the Known Exploited Vulnerabilities Catalog on August
9, 2022. According to industry reporting, a malicious cyber actor is selling a
cross-site scripting (XSS) exploit kit for the ZCS vulnerability to CVE 2022
30333. A Metasploit module that creates a RAR file that can be emailed to a
ZCS server to exploit CVE-2022-30333 is also available.[10 ] CVE-2022-24682
CVE-2022-24682 is a medium-severity vulnerability that impacts ZCS webmail
clients running releases before 8.8.15 patch 30 (update 1), which contain a
cross-site scripting (XSS) vulnerability allowing malicious actors to steal
session cookie files. Researchers from Volexity shared this vulnerability on
February 3, 2022[11], and Zimbra issued a fix on February 4, 2022.[12] CISA
added this vulnerability to the Known Exploited Vulnerabilities Catalog on
February 25, 2022. DETECTION METHODS Note: CISA and the MS-ISAC will update
this section with additional IOCs and signatures as further information
becomes available. CISA recommends administrators, especially at organizations
that did not immediately update their ZCS instances upon patch release, to
hunt for malicious activity using the following third-party detection
signatures: Hunt for IOCs including: 207.148.76[.]235 – a Cobalt Strike
command and control (C2) domain Update August 22, 2022: Deploy Snort
signatures to detect malicious activity: alert tcp any any -> any any
(msg:”ZIMBRA: HTTP POST content data ‘.jsp’ file'”; sid:x; rev:1;
flow:established,to_server; flowbits:isnotset,1.tagged; content:”POST”;
http_method; content:”|2f|service|2f|extension|2f|backup|2f|mboximport”;
nocase; http_uri; content:”file|3a|”; nocase; http_client_body;
content:”|2e|jsp”; http_client_body; fast_pattern; flowbits:set,1.tagged;
tag:session,10,packets; priority:2; classtype:http-content;
reference:cve,2022-30333; metadata:service http; metadata:pattern
HTTP-P004,usgref 179822-22,reqid REQ-2022-015618;) alert tcp any any -> any
any (msg:”ZIMBRA: Client HTTP Header ‘QIHU 360SE'”; sid:x; rev:1;
flow:established,to_server; flowbits:isnotset,1.tagged; content:”POST”;
http_method; content:”|2f|service|2f|extension|2f|backup|2f|mboximport”;
nocase; http_uri; content:”QIHU|20|360SE”; nocase; http_header; fast_pattern;
flowbits:set,1.tagged; tag:session,10,packets; priority:2; classtype:http-
header; reference:cve,2022-30333; metadata:service http; metadata:pattern
HTTP-P002,usgref 179822-22,reqid REQ-2022-015619;) alert tcp any any -> any
any (msg:”ZIMBRA: HTTP URI ‘zmlocalconfig|3a|-s'”; sid:x; rev:1;
flow:established,to_server; flowbits:isnotset,1.tagged; content:”|2e|jsp”;
nocase; http_uri; content:”zmlocalconfig|3a|-s”; fast_pattern; nocase;
http_uri; flowbits:set,1.tagged; tag:session,10,packets; priority:2;
classtype:http-header; reference:cve,2022-30333; metadata:service http;
metadata:pattern HTTP-P001,usgref 179822-22,reqid REQ-2022-015623;) Deploy
third-party YARA rules to detect malicious activity: See Volexity’s Mass
Exploitation of (Un)authenticated Zimbra RCE: CVE-2022-27925 Mitigations CISA
and the MS-ISAC recommend organizations upgrade to the latest ZCS releases as
noted on Zimbra Security – News & Alerts and Zimbra Security Advisories . See
Volexity’s Mass Exploitation of (Un)authenticated Zimbra RCE: CVE-2022-27925
for mitigation steps. Additionally, CISA and the MS-ISAC recommend
organizations apply the following best practices to reduce risk of compromise:
Maintain and test an incident response plan. Ensure your organization has a
vulnerability management program in place and that it prioritizes patch
management and vulnerability scanning of known exploited vulnerabilities .
Note: CISA’s Cyber Hygiene Services (CyHy) are free to all state, local,
tribal, and territorial (SLTT) organizations, as well as public and private
sector critical infrastructure organizations: cisa.gov/cyber-hygiene-services
. Properly configure and secure internet-facing network devices. Do not expose
management interfaces to the internet. Disable unused or unnecessary network
ports and protocols. Disable/remove unused network services and devices. Adopt
zero-trust principles and architecture , including: Micro-segmenting networks
and functions to limit or block lateral movements. Enforcing phishing-
resistant MFA for all users and virtual private network (VPN) connections.
Restricting access to trusted devices and users on the networks. INCIDENT
RESPONSE If an organization’s system has been compromised by active or
recently active threat actors in their environment, CISA and the MS-ISAC
recommend the following initial steps: Collect and review artifacts , such as
running processes/services, unusual authentications, and recent network
connections. Quarantine or take offline potentially affected hosts . Reimage
compromised hosts . Provision new account credentials . Report the compromise
to CISA via CISA’s 24/7 Operations Center (report@cisa.gov or 888-282-0870).
SLTT government entities can also report to the MS-ISAC (SOC@cisecurity.org or
866-787-4722). See the joint CSA from the cybersecurity authorities of
Australia, Canada, New Zealand, the United Kingdom, and the United States on
Technical Approaches to Uncovering and Remediating Malicious Activity for
additional guidance on hunting or investigating a network, and for common
mistakes in incident handling. CISA and the MS-ISAC also encourage government
network administrators to see CISA’s Federal Government Cybersecurity Incident
and Vulnerability Response Playbooks . Although tailored to federal civilian
branch agencies, these playbooks provide detailed operational procedures for
planning and conducting cybersecurity incident and vulnerability response
activities. ACKNOWLEDGEMENTS CISA and the MS-ISAC would like to thank Volexity
and Secureworks for their contributions to this advisory. DISCLAIMER The
information in this report is being provided “as is” for informational
purposes only. CISA and the MS-ISAC do not provide any warranties of any kind
regarding this information. CISA and the MS-ISAC do not endorse any commercial
product or service, including any subjects of analysis. Any reference to
specific commercial products, processes, or services by service mark,
trademark, manufacturer, or otherwise, does not constitute or imply
endorsement, recommendation, or favoring. References [1] Hackers are actively
exploiting password-stealing flaw in Zimbra [2] CISA adds Zimbra email
vulnerability to its exploited vulnerabilities catalog [3] CVE-2022-27925
detail [4] Mass exploitation of (un)authenticated Zimbra RCE: CVE-2022-27925
[5] CVE-2022-37042 detail [6] Authentication bypass in MailboxImportServlet
vulnerability [7] CVE-2022-30333 detail [8] UnRAR vulnerability exploited in
the wild, likely against Zimbra servers [9] Zimbra Collaboration Kepler 9.0.0
patch 25 GA release [10] Zimbra UnRAR path traversal [11] Operation
EmailThief: Active exploitation of zero-day XSS vulnerability in Zimbra [12]
Hotfix available 5 Feb for zero-day exploit vulnerability in Zimbra 8.8.15
Revisions August 16, 2022: Initial Version August 22, 2022: Added Snort
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