CVE-2023-29383

NameCVE-2023-29383
DescriptionIn 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs1034482

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
shadow (PTS)buster1:4.5-1.1vulnerable
bullseye1:4.8.1-1vulnerable
bookworm1:4.13+dfsg1-1vulnerable
sid, trixie1:4.13+dfsg1-5fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
shadowsource(unstable)1:4.13+dfsg1-21034482

Notes

[bookworm] - shadow <no-dsa> (Minor issue)
[bullseye] - shadow <no-dsa> (Minor issue)
[buster] - shadow <no-dsa> (Minor issue)
https://github.com/shadow-maint/shadow/pull/687
Fixed by: https://github.com/shadow-maint/shadow/commit/e5905c4b84d4fb90aefcd96ee618411ebfac663d (4.14.0-rc1)
https://www.trustwave.com/en-us/resources/security-resources/security-advisories/?fid=31797
https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/cve-2023-29383-abusing-linux-chfn-to-misrepresent-etc-passwd/

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