CVE-2023-29383 Information

Description

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 ## Reference https://github.com/shadow-maint/shadow/commit/e5905c4b84d4fb90aefcd96ee618411ebfac663d https://www.trustwave.com/en-us/resources/security-resources/security-advisories/?fid=31797 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/