glibc: Information leak with LD_DEBUG

Background

The GNU C library defines various Unix-like “system calls” and other basic facilities needed for a standard POSIX-like application to operate.

Description

Silvio Cesare discovered a potential information leak in glibc. It allows LD_DEBUG on SUID binaries where it should not be allowed. This has various security implications, which may be used to gain confidentional information.

Impact

An attacker can gain the list of symbols a SUID application uses and their locations and can then use a trojaned library taking precendence over those symbols to gain information or perform further exploitation.

Workaround

There is no known workaround at this time. All users are encouraged to upgrade to the latest available version of glibc.

Resolution

All glibc users should upgrade to the latest version:

 # emerge sync
 
 # emerge -pv your_version
 # emerge your_version