CVE-2022-27925 – A Deep Dive into Zimbra Collaboration's Directory Traversal Vulnerability Exploitation

In this long read, we'll be exploring the details of a recently disclosed vulnerability in Zimbra Collaboration (aka ZCS) versions 8.8.15 and 9., identified as CVE-2022-27925. We'll look into the mboximport functionality, which processes a ZIP archive and extracts files from it, and see how an authenticated user with administrator rights can exploit this vulnerability to achieve directory traversal and potentially compromise the system.

An Overview of CVE-2022-27925

CVE-2022-27925 is a vulnerability in Zimbra Collaboration Suite, a popular open-source email, calendar, and collaboration platform. The vulnerability allows an authenticated user with administrator rights to upload arbitrary files to the system through the mboximport functionality, leading to directory traversal.

A directory traversal attack occurs when an attacker can access files and directories in the application's file system by injecting the path of the target file or directory. In this case, a malicious ZIP file containing specially crafted filepaths can result in the extraction of files into unintended locations of the server.

Consider the following example of a malicious ZIP file

malicious.zip:
-> ../../../etc/passwd
-> ../../../usr/local/zimbra/log/important.log
-> typical-user-data.json

When this ZIP file is uploaded and processed by the vulnerable mboximport functionality in Zimbra Collaboration Suite, it would lead to directory traversal, potentially overwriting or adding arbitrary files to the system.

Here is a code snippet that demonstrates the vulnerability with a typical standard parameter processing section in mboximport (for educational purposes only):

import zipfile

def extract_zip(file_path, target_path):
    with zipfile.ZipFile(file_path, 'r') as zip_ref:
        zip_ref.extractall(target_path)

if __name__ == "__main__":
    zip_file_path = "/path/to/malicious.zip"
    extract_zip(zip_file_path, "/usr/local/zimbra/mailbox/")

In this example, when the malicious.zip is processed, the files inside would be extracted to locations outside the intended target folder (/usr/local/zimbra/mailbox/), potentially overwriting important system files or adding new files with malicious content.

Original References

The vulnerability was first reported by Sébastien GIORIA (OCS Infogérance), and full details can be found at the following links:

- CVE-2022-27925 Official CVE Record: https://cve.mitre.org/{cve-id}
- Zimbra Security Advisory: https://wiki.zimbra.com/wiki/{security-advisory-id}
- NIST NVD Vulnerability Profile: https://nvd.nist.gov/vuln/detail/CVE-2022-27925

To successfully exploit this vulnerability, an attacker would need to follow these steps

1. Obtain a valid administrator account in the Zimbra Collaboration Suite platform. This could be done through social engineering, password guessing, or other means.

2. Create a malicious ZIP file containing files with specially crafted filepaths, as demonstrated earlier in this post.

3. Use the mboximport functionality of the Zimbra Collaboration Suite to upload and process the malicious ZIP file. This would cause the extracted files to be placed in unintended locations, possibly leading to system compromise.

Mitigation and Conclusion

To protect against this vulnerability, organizations running Zimbra Collaboration Suite 8.8.15 or 9. should immediately update their installations to the latest patched versions. Details on the patches can be found in the Zimbra Security Advisory mentioned in the links above.

In summary, CVE-2022-27925 is a critical vulnerability that allows attackers to traverse directories and gain access to sensitive information on the vulnerable servers. It highlights the importance of keeping software up-to-date and implementing strong security policies and access controls within any organization.

Timeline

Published on: 04/21/2022 00:15:00 UTC
Last modified on: 08/24/2022 15:15:00 UTC