Executive brief
Sendmail, a widely used mail transfer agent, contains a vulnerability in its default configuration. An attacker can use a specific mail alias to overwrite sensitive system files. This could lead to system instability or unauthorized modification of critical configuration data.
Technical details
The Sendmail 'decode' alias, which is often enabled by default in older installations, allows an attacker to pipe mail through the uudecode utility. Because uudecode can be instructed to output files to specific paths, a remote attacker can send a specially crafted email that overwrites arbitrary files on the local filesystem with the permissions of the Sendmail process. This is a file overwrite vulnerability that does not require authentication. Remediation typically involves removing the 'decode' entry from the mail aliases file.
Affected products
- Sendmail Sendmail
Timeline
- 1996-12-10: disclosed