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Webmin, Usermin: Remote code execution through PAM authentication


1.  Gentoo Linux Security Advisory

Version Information

Advisory Reference GLSA 200509-17 / Webmin Usermin
Release Date September 24, 2005
Latest Revision September 24, 2005: 01
Impact high
Exploitable remote
Package Vulnerable versions Unaffected versions Architecture(s)
app-admin/webmin < 1.230 >= 1.230 All supported architectures
app-admin/usermin < 1.160 >= 1.160 All supported architectures

Related bugreports: #106705


If Webmin or Usermin is configured to use full PAM conversations, it is vulnerable to the remote execution of arbitrary code with root privileges.

2.  Impact Information


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-mails.


Keigo Yamazaki discovered that the webserver, used in both Webmin and Usermin, does not properly validate authentication credentials before sending them to the PAM (Pluggable Authentication Modules) authentication process. The default configuration shipped with Gentoo does not enable the "full PAM conversations" option and is therefore unaffected by this flaw.


A remote attacker could bypass the authentication process and run any command as the root user on the target server.

3.  Resolution Information


Do not enable "full PAM conversations" in the Authentication options of Webmin and Usermin.


All Webmin users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=app-admin/webmin-1.230"

All Usermin users should upgrade to the latest version:

Code Listing 3.2: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=app-admin/usermin-1.160"

4.  References


Page updated September 24, 2005

Summary: This is a Gentoo Linux Security Advisory

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