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GHSA-vcvr-v426-3m3m
No affected components available
Impact
Triggering the office converter with a specially crafted file name allows writing the attachment's content to an attacker-controlled location on the server as long as the Java process has write access to that location. In particular in the combination with attachment moving, a feature introduced in XWiki 14.0, this is easy to reproduce but it also possible to reproduce in versions as old as XWiki 3.5 by uploading the attachment through the REST API which doesn't remove / or \ from the filename. As the mime type of the attachment doesn't matter for the exploitation, this could e.g., be used to replace the jar-file of an extension which would allow executing arbitrary Java code and thus impact the confidentiality, integrity and availability of the XWiki installation. To reproduce the issue on versions since XWiki 14.0, execute the following steps:
- Activate the office server
- Upload an arbitrary file with the extension .doc, e.g., to your user profile (you can use a regular plain text file, only the extension matters).
- Use the attachment move feature to rename the file to ../../../../../tmp/Hello from XWiki.txt where the latter part is the location of a file you want to write on the server. The number of ../ depends on the directory depth, the provided example should work on Linux with the demo distribution.
- Click the "preview" link to trigger the office converter
For information how to reproduce on older versions, see the Jira issue.
To the best of our knowledge, this attack is not possible when the office conversion process doesn't run as the code fails before the file is written.
Patches
This vulnerability has been patched in XWiki 14.10.8 and 15.3RC1.
Workarounds
There are no known workarounds apart from disabling the office converter.
References
- https://jira.xwiki.org/browse/XWIKI-20715
- https://github.com/xwiki/xwiki-platform/commit/45d182a4141ff22f3ff289cf71e4669bdc714544
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.
Active exploitation in the wild has been confirmed. Immediate patching or mitigation is required.
Probability that this vulnerability will be exploited in the wild within the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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