Unix and Linux admin console exposed by bug

A bug in Usermin, a widely-used administration console for Unix and Linux, could allow an attacker to run malicious code via a specially-crafted email, according to security researchers.

Usermin allows users of Unix and Linux to administer their own accounts on a network via a Web-based interface, including reading email. The tool isn't included in Unix or Linux distributions by default, but is often used with Webmin, one of the most popular system administration tools, which ships with Linux distributions such as Suse, Mandrake and Gentoo. A separate, less serious bug affects both Webmin and Usermin, researchers said.

A flaw in Usermin's webmail feature allows an attacker to inject malicious shell code in a specially-crafted email, according to an advisory from Gentoo. This bug could lead to the remote execution of malicious code with the privileges of the user running Webmin or Usermin. Webmin contains all the functionality of Usermin, including the vulnerable webmail feature, experts said.

"Certain parts of the emails aren't properly validated before Usermin is used in an insecure call to local resources," said Thomas Kristensen, chief technical officer of Danish security firm Secunia. "This can be exploited by sending a malicious mail to a user using Usermin." In its advisory Secunia gave the vulnerability a "highly critical" rating, its second most severe category.

The second bug could only be exploited by a local user who knew Webmin or Usermin was going to be installed. The applications write to the location /tmp/.webmin without first checking that such a location already exists; a malicious user could create a link at /tmp/.webmin pointing to important files (for example /etc/passwd), causing those files to be overwritten when the application was installed.

Users are advised to upgrade to the latest versions of Usermin and Webmin.

Join the newsletter!


Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Matthew Broersma

Show Comments

Father’s Day Gift Guide

Brand Post

Bitdefender 2019

Bitdefender solutions stop attacks before they even begin! Get cybersecurity that 500 MILLION users already have and trust.

Most Popular Reviews

Latest Articles


PCW Evaluation Team

Luke Hill


I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Laura Johnston

MSI GS65 Stealth Thin

If you can afford the price tag, it is well worth the money. It out performs any other laptop I have tried for gaming, and the transportable design and incredible display also make it ideal for work.

Andrew Teoh

Brother MFC-L9570CDW Multifunction Printer

Touch screen visibility and operation was great and easy to navigate. Each menu and sub-menu was in an understandable order and category

Louise Coady

Brother MFC-L9570CDW Multifunction Printer

The printer was convenient, produced clear and vibrant images and was very easy to use

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?