scponly: Multiple privilege escalation issues — GLSA 200512-17

Local users can exploit an scponly flaw to gain root privileges, and scponly restricted users can use another vulnerability to evade shell restrictions.

Affected Packages

net-misc/scponly on all architectures
Affected versions < 4.2
Unaffected versions >= 4.2

Background

scponly is a restricted shell, allowing only a few predefined commands. It is often used as a complement to OpenSSH to provide access to remote users without providing any remote execution privileges.

Description

Max Vozeler discovered that the scponlyc command allows users to chroot into arbitrary directories. Furthermore, Pekka Pessi reported that scponly insufficiently validates command-line parameters to a scp or rsync command.

Impact

A local attacker could gain root privileges by chrooting into arbitrary directories containing hardlinks to setuid programs. A remote scponly user could also send malicious parameters to a scp or rsync command that would allow to escape the shell restrictions and execute arbitrary programs.

Workaround

There is no known workaround at this time.

Resolution

All scponly users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=net-misc/scponly-4.2"

References

Release Date
December 29, 2005

Latest Revision
May 22, 2006: 02

Severity
high

Exploitable
local and remote

Bugzilla entries