The French Security Incident Response Team (FrSIRT) has reported a pair of vulnerabilities in Webmin and Usermin that could be exploited by remote attackers.
FrSIRT said in its advisory that the pair of flaws pose problems for users of the Webmin and Usermin web-based interfaces. Both are written in Perl 5 and employ CGI scripts deliver their functionality.
The advisory described the two issues, as reported to FrSIRT by Keigo Yamazaki, Little eArth Corporation:
The first issue is due to an error when handling malformed URLs, which could be exploited by attackers to cause malicious scripting code to be executed by the user’s browser.
The second flaw is due to an error when handling malformed URLs, which could be exploited by attackers to display the source code or arbitrary CGI and Perl scripts.
The flaws pose a moderate risk to systems running vulnerable versions of Webmin, as they are remotely exploitable. Cross-site scripting would be the attack vector used, according to the information posted at Secunia about the issues:
1) Some input passed in a NULL character (“%00”) in the URL isn’t properly verified before being used. This can be exploited to disclose the source code of arbitrary CGI and Perl programs.
2) Some input passed in a NULL character (“%00”) in the URL isn’t properly sanitised before being returned to the user. This can be exploited to execute arbitrary HTML and script code in a user’s browser session in context of an affected site.
Webmin developers have fixed both vulnerabilities in the development version of Webmin, 1.296, and Usermin, version 1.226.
System administrators on Unix use Webmin to make configuration changes for services and manage accounts. Usermin provides an interface for regular users to read mail and do other user-level functions. Blogger Chris Dorner hosts a walkthrough of Webmin and screenshots of it in action.
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David Utter is a staff writer for murdok covering technology and business.
