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

Cybersecurity
Original release date: August 16, 2022 | Last revised: August 29, 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 Download the IOCs: .stix
12.2 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. Based on evidence of active exploitation, CISA added this vulnerability
to the Known Exploited Vulnerabilities Catalog on August 4, 2022. Due to 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.[1] 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 23, 2022: Deploy Snort
signatures to detect malicious activity: alert tcp any any -> any any
(msg:”ZIMBRA: HTTP POST content data ‘.jsp’ file'”; sid:x;
flow:established,to_server; 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; classtype:http-content;
reference:cve,2022-30333;) alert tcp any any -> any any (msg:”ZIMBRA: Client
HTTP Header ‘QIHU 360SE'”; sid:x; flow:established,to_server; 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;
classtype:http-header; reference:cve,2022-30333;) alert tcp any any -> any any
(msg:”ZIMBRA:HTTP GET URI for Zimbra Local Config”; sid:x;
flow:established,to_server;
content:”/public/jsp/runas.jsp?pwd=zim&i;=/opt/zimbra/bin/zmlocalconfig|3a|-s”;
http_uri; classtype:http-uri; reference:cve,2022-30333;) 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] 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
[14] Hackers are actively exploiting password-stealing flaw in Zimbra [13]
CISA adds Zimbra email vulnerability to its exploited vulnerabilities catalog
Revisions August 16, 2022: Initial Version August 22, 2022: Added Snort
Signatures August 23, 2022: Updated Detection Methods Snort Signatures This
product is provided subject to this Notification and this Privacy & Use
policy.Original release date: August 16, 2022 | Last revised: August 29, 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 Download the IOCs: .stix
12.2 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. Based on evidence of active exploitation, CISA added this vulnerability
to the Known Exploited Vulnerabilities Catalog on August 4, 2022. Due to 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.[1] 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 23, 2022: Deploy Snort
signatures to detect malicious activity: alert tcp any any -> any any
(msg:”ZIMBRA: HTTP POST content data ‘.jsp’ file'”; sid:x;
flow:established,to_server; 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; classtype:http-content;
reference:cve,2022-30333;) alert tcp any any -> any any (msg:”ZIMBRA: Client
HTTP Header ‘QIHU 360SE'”; sid:x; flow:established,to_server; 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;
classtype:http-header; reference:cve,2022-30333;) alert tcp any any -> any any
(msg:”ZIMBRA:HTTP GET URI for Zimbra Local Config”; sid:x;
flow:established,to_server;
content:”/public/jsp/runas.jsp?pwd=zim&i;=/opt/zimbra/bin/zmlocalconfig|3a|-s”;
http_uri; classtype:http-uri; reference:cve,2022-30333;) 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] 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
[14] Hackers are actively exploiting password-stealing flaw in Zimbra [13]
CISA adds Zimbra email vulnerability to its exploited vulnerabilities catalog
Revisions August 16, 2022: Initial Version August 22, 2022: Added Snort
Signatures August 23, 2022: Updated Detection Methods Snort Signatures This
product is provided subject to this Notification and this Privacy & Use
policy. August 16 2022 10:38:42
AA22-228A: Threat Actors Exploiting Multiple CVEs Against Zimbra Collaboration Suite

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