Debian Security Advisory

isdnutils -- Incorrect permissions on xmonisdn

Date Reported:
07 Aug 1999
Affected Packages:
Security database references:
In Mitre's CVE dictionary: CVE-1999-0706.
More information:
Xmonisdn is an X applet that shows the status of the ISDN links. You can configure it to run two scripts when the left or right mouse button are clicked on it. Xmonisdn was installed setuid root so that the scripts could do things like add and delete the default route. However, while the scripts were checked for owner root and not writable by group or others the scripts are run via the system() library function, which spawns a shell to run it. This means that the scripts are open to attack via IFS and/or PATH manipulation.

However, the setuid root isn't necessary anymore as the ISDN system now offers other ways of preventing dialouts besides by manipulating network routes. This can be done by anyone who can access /dev/isdnctrl0 and /dev/isdninfo. On debian systems those are rw for group dialout, so if xmonisdn is run by someone in group dialout, they can execute the necessary isdnctrl commands.

Fixed in:

Debian GNU/Linux 2.1 (slink)


MD5 checksums of the listed files are available in the original advisory.