UNIX Symbolic Link (Symlink) Following vulnerability in the trousers package of SUSE Linux Enterprise Server 15 SP1; openSUSE Factory allowed local attackers escalate privileges from user tss to root. This issue affects: SUSE Linux Enterprise Server 15 SP1 trousers versions prior to 0.3.14-6.3.1. openSUSE Factory trousers versions prior to 0.3.14-7.1.

An issue was discovered in TrouSerS through 0.3.14. If the tcsd daemon is started with root privileges instead of by the tss user, it fails to drop the root gid privilege when no longer needed.

An issue was discovered in TrouSerS through 0.3.14. If the tcsd daemon is started with root privileges, the tss user still has read and write access to the /etc/tcsd.conf file (which contains various settings related to this daemon).

An issue was discovered in TrouSerS through 0.3.14. If the tcsd daemon is started with root privileges, the creation of the system.data file is prone to symlink attacks. The tss user can be used to create or corrupt existing files, which could possibly lead to a DoS attack.

From Andy Lutomirski

The attached Python script will segfault tcsd.

This particular vulnerability is a read from an attacker-controlled address, so getting anything more severe than information disclosure out of it may be difficult. But there is a lot of fishy input validation, and it may be possible to persuade the code to write out of bounds as well. It is certainly possible to cause memory allocation failures, but I haven't seen one that's unchecked yet.

Upstream report (currently private) here: https://sourceforge.net/tracker/?func=detail&atid=704358&aid=3473554&groupid=126012