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scponly: Multiple privilege escalation issues


1.  Gentoo Linux Security Advisory

Version Information

Advisory Reference GLSA 200512-17 / scponly
Release Date December 29, 2005
Latest Revision May 22, 2006: 02
Impact high
Exploitable local and remote
Package Vulnerable versions Unaffected versions Architecture(s)
net-misc/scponly < 4.2 >= 4.2 All supported architectures

Related bugreports: #116526


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

2.  Impact Information


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.


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.


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.

3.  Resolution Information


There is no known workaround at this time.


All scponly users should upgrade to the latest version:

Code Listing 3.1: Resolution

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

4.  References


Page updated December 29, 2005

Summary: This is a Gentoo Linux Security Advisory

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