“Secunia Advisory: SA16869

Critical: Extremely critical

Impact: System access

Where: From remote

Solution Status: Unpatched

Software: Mozilla Firefox 1.x

Peter Zelezny has discovered a vulnerability in Firefox, which can be exploited by malicious people to compromise a user’s system.

The vulnerability is caused due to the shell script used to launch Firefox parsing shell commands that are enclosed within backticks in the URL provided via the command line. This can e.g. be exploited to execute arbitrary shell commands by tricking a user into following a malicious link in an external application which uses Firefox as the default browser (e.g. the mail client Evolution on Red Hat Enterprise Linux 4).

This vulnerability can only be exploited on Unix / Linux based environments.

The vulnerability has been confirmed in version 1.0.6 on Fedora Core 4 and Red Hat Enterprise Linux 4. Other versions and platforms may also be affected.

Solution: Do not open links in Firefox from external applications.

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