Shadow-utils is an encryption and account management package freely distributed for many Linux implementations. The useradd program in this package creates insecure temporary files with predictable names in a write-protected directory. If this directory is changed to be writable, an attacker may be able to use a symbolic link attack to overwrite arbitrary files.
The useradd program calls the passwd program, which stores temporary files with predictable names in /etc/default, a protected directory. The program does not check for prior existence or ownership of these files. Useradd normally runs with setuid root privileges.
If /etc/default is changed to be world-writable, an attacker may be able to create a symbolic link with predictable name, and point it to any writable file on the system. This may cause corruption of the file.
Apply vendor patches; see the Systems Affected section below.
Change /etc/default to not be world-writable.
This vulnerability was first reported by Greg Kroah-Hartman
This document was last modified by Tim Shimeall.
|Date First Published:||2001-11-08|
|Date Last Updated:||2001-11-08 18:19 UTC|