Executive brief
A vulnerability in the SGI IRIX operating system allows local users to gain full administrative (root) control of the system. The issue exists in two utilities, ipxchk and ipxlink, which are used for Novell IPX networking support. By manipulating system environment variables, a standard user can trick these utilities into executing unauthorized commands with elevated privileges.
Technical details
The ipxchk and ipxlink binaries in SGI IRIX 6.3 are installed setuid root by default to support Novell IPX networking. These utilities fail to clear or sanitize the Internal Field Separator (IFS) environment variable before making system calls via the system() function. A local attacker can exploit this by setting a custom IFS value to redefine command delimiters, causing the setuid binaries to execute an arbitrary malicious program instead of the intended system utility. While SGI initially attempted to patch this by hardcoding the IFS variable, the final resolution involved removing the setuid bit from ipxlink and removing ipxchk entirely in patch SG0002869.
Affected products
- SGI IRIX 6.3 O2 R10K 6.3
Timeline
- 1997-06-01: disclosed: Initial report to SGI by researcher Fabrice Planchon.
- 1998-04-08: advisory: Public disclosure on Bugtraq.
- 1998-04-08: patched: Patch SG0002869 released to address the issue.