CVE-2023-29383
First published: Fri Apr 14 2023(Updated: )
In Shadow 4.13, it is possible to inject control characters into fields provided to the SUID program chfn (change finger). Although it is not possible to exploit this directly (e.g., adding a new user fails because \n is in the block list), it is possible to misrepresent the /etc/passwd file when viewed. Use of \r manipulations and Unicode characters to work around blocking of the : character make it possible to give the impression that a new user has been added. In other words, an adversary may be able to convince a system administrator to take the system offline (an indirect, social-engineered denial of service) by demonstrating that "cat /etc/passwd" shows a rogue user account.
Credit: cve@mitre.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Shadow Project | =4.13 | |
| =4.13 |
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Reference Links
- https://github.com/shadow-maint/shadow/commit/e5905c4b84d4fb90aefcd96ee618411ebfac663d
- https://github.com/shadow-maint/shadow/pull/687
- https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/cve-2023-29383-abusing-linux-chfn-to-misrepresent-etc-passwd/
- https://www.trustwave.com/en-us/resources/security-resources/security-advisories/?fid=31797
- https://www.ibm.com/support/pages/node/7232197 (Advisory)
Frequently Asked Questions
What is the severity of CVE-2023-29383?
CVE-2023-29383 has been assigned a severity rating that indicates it poses a risk of misrepresenting user data.
How do I fix CVE-2023-29383?
To mitigate CVE-2023-29383, upgrading to a patched version of Shadow beyond 4.13 is recommended.
What does CVE-2023-29383 exploit?
CVE-2023-29383 allows the injection of control characters into fields provided to the SUID program chfn.
Is CVE-2023-29383 exploitable?
CVE-2023-29383 is not directly exploitable to create new users but can misrepresent the /etc/passwd file in certain scenarios.
What software is affected by CVE-2023-29383?
Shadow version 4.13 is affected by CVE-2023-29383.
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