Webmin, Usermin: Multiple vulnerabilities in Usermin

Background

Webmin and Usermin are web-based system administration consoles. Webmin allows an administrator to easily configure servers and other features. Usermin allows users to configure their own accounts, execute commands, and read e-mail. The Usermin functionality, including webmail, is also included in Webmin.

Description

There is an input validation bug in the webmail feature of Usermin.

Additionally, the Webmin and Usermin installation scripts write to /tmp/.webmin without properly checking if it exists first.

Impact

The first vulnerability allows a remote attacker to inject arbitrary shell code in a specially-crafted e-mail. This could lead to remote code execution with the privileges of the user running Webmin or Usermin.

The second could allow local users who know Webmin or Usermin is going to be installed to have arbitrary files be overwritten by creating a symlink by the name /tmp/.webmin that points to some target file, e.g. /etc/passwd.

Workaround

There is no known workaround at this time.

Resolution

All Usermin users should upgrade to the latest version:

 # emerge sync
 
 # emerge -pv ">=app-admin/usermin-1.090"
 # emerge ">=app-admin/usermin-1.090"

All Webmin users should upgrade to the latest version:

 # emerge sync
 
 # emerge -pv ">=app-admin/webmin-1.160"
 # emerge ">=app-admin/webmin-1.160"