Berkeley Sendmail Daemon Mode Vulnerability
BID:716
Info
Berkeley Sendmail Daemon Mode Vulnerability
| Bugtraq ID: | 716 |
| Class: | Input Validation Error |
| CVE: | |
| Remote: | No |
| Local: | Yes |
| Published: | Nov 16 1996 12:00AM |
| Updated: | Nov 16 1996 12:00AM |
| Credit: | This vulnerability was discovered by Leshka Zakharoff <[email protected]> and posted to Bugtraq on 16 November 1996. |
| Vulnerable: |
Redhat Linux 4.0 IBM AIX 4.2 HP HP-UX 10.20 HP HP-UX 10.10 HP HP-UX 10.0 1 HP HP-UX 10.0 FreeBSD FreeBSD 2.1.6 FreeBSD FreeBSD 2.1.5 Eric Allman Sendmail 8.8.2 Eric Allman Sendmail 8.8.1 Eric Allman Sendmail 8.8 Eric Allman Sendmail 8.7 .x Caldera Network Desktop 1.0 BSDI BSD/OS 2.1 |
| Not Vulnerable: |
Eric Allman Sendmail 8.8.3 |
Discussion
Berkeley Sendmail Daemon Mode Vulnerability
This description was taken from the CERT advisory:
Sendmail is often run in daemon mode so that it can "listen" for incoming mail connections on the standard SMTP networking port, usually port 25. The root user is the only user allowed to start sendmail this way, and sendmail contains code intended to enforce this restriction.
Unfortunately, due to a coding error, sendmail can be invoked in daemon mode in a way that bypasses the built-in check. When the check is bypassed, any local user is able to start sendmail in daemon mode. In addition, as of version 8.7, sendmail will restart itself when it receives a SIGHUP signal. It does this restarting operation by re-executing itself using the exec(2) system call. Re-executing is done as the root user. By manipulating the sendmail environment, the user can then have sendmail execute an arbitrary program with root privileges.
This description was taken from the CERT advisory:
Sendmail is often run in daemon mode so that it can "listen" for incoming mail connections on the standard SMTP networking port, usually port 25. The root user is the only user allowed to start sendmail this way, and sendmail contains code intended to enforce this restriction.
Unfortunately, due to a coding error, sendmail can be invoked in daemon mode in a way that bypasses the built-in check. When the check is bypassed, any local user is able to start sendmail in daemon mode. In addition, as of version 8.7, sendmail will restart itself when it receives a SIGHUP signal. It does this restarting operation by re-executing itself using the exec(2) system call. Re-executing is done as the root user. By manipulating the sendmail environment, the user can then have sendmail execute an arbitrary program with root privileges.
Solution / Fix
Berkeley Sendmail Daemon Mode Vulnerability
Solution:
Install version 8.8.3 of sendmail or install a vendor supplied patch.
Solution:
Install version 8.8.3 of sendmail or install a vendor supplied patch.