Bugtraq mailing list archives
Re: hard links on Linux create local DoS vulnerability and security problems
From: Bruno Lustosa <bruno () lustosa net>
Date: Mon, 24 Nov 2003 16:25:37 -0200
* Jakob Lell <jlell () JakobLell de> [24-11-2003 16:11]:
Furthermore, users can even create links to a setuid binary. If there is a security whole like a buffer overflow in any setuid binary, a cracker can create a hard link to this file in his home directory. This link still exists when the administrator has fixed the security whole by removing or replacing the insecure program. This makes it possible for a cracker to keep a security whole open until an exploit is available. It is even possible to create links to every setuid program on the system. This doesn't create new security wholes but makes it more likely that they are exploited.
Just checked this on 2.6.0-test9, and it will not work. When you create a hard link to a setuid or any other file, it will inherit the same owner and mode of the original. However, if the original file is changed (owner, group, mode, or content), the link will reflect those changes as well. -- Bruno Lustosa, aka Lofofora | Email: bruno () lustosa net Network Administrator/Web Programmer | ICQ UIN: 1406477 Rio de Janeiro - Brazil |
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Current thread:
- hard links on Linux create local DoS vulnerability and security problems Jakob Lell (Nov 24)
- Re: hard links on Linux create local DoS vulnerability and security problems Brian Bennett (Nov 24)
- Re: hard links on Linux create local DoS vulnerability and security problems Bruno Lustosa (Nov 24)
- Re: hard links on Linux create local DoS vulnerability and security problems David F. Skoll (Nov 24)
- Re: hard links on Linux create local DoS vulnerability and security problems Steven Leikeim (Nov 24)
- Re: [Full-Disclosure] hard links on Linux create local DoS vulnerability and security problems Michal Zalewski (Nov 24)
- <Possible follow-ups>
- Re: hard links on Linux create local DoS vulnerability and security problems Alan J Rosenthal (Nov 24)
- Re: hard links on Linux create local DoS vulnerability and security problems Carl Ekman (Nov 24)
- Re: hard links on Linux create local DoS vulnerability and security problems Casper Dik (Nov 24)