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.

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UBUNTU-CVE-2023-29383

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...

PT-2023-9380 · Shadow +3 · Shadow +3

Name of the Vulnerable Software and Affected Versions: Shadow version 4.13 Description: The issue is related to insufficient neutralization of special elements in a request, which can be exploited to impact data integrity. In Shadow 4.13, it is possible to inject control characters into fields...