OpenSSH, Dropbear: Insecure use of system() call

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200602-11 / OpenSSH
Release Date	February 20, 2006
Latest Revision	February 20, 2006: 01
Impact	low
Exploitable	local

Package	Vulnerable versions	Unaffected versions	Architecture(s)
net-misc/openssh	< 4.2_p1-r1	>= 4.2_p1-r1	All supported architectures
net-misc/dropbear	< 0.47-r1	>= 0.47-r1	All supported architectures

Related bugreports: #119232

Synopsis

A flaw in OpenSSH and Dropbear allows local users to elevate their privileges via scp.

2. Impact Information

Background

OpenSSH is a free application suite consisting of server and clients that replace tools like telnet, rlogin, rcp and ftp with more secure versions offering additional functionality. Dropbear is an SSH server and client designed with a small memory footprint that includes OpenSSH scp code.

Description

To copy from a local filesystem to another local filesystem, scp constructs a command line using 'cp' which is then executed via system(). Josh Bressers discovered that special characters are not escaped by scp, but are simply passed to the shell.

Impact

By tricking other users or applications to use scp on maliciously crafted filenames, a local attacker user can execute arbitrary commands with the rights of the user running scp.

3. Resolution Information

Workaround

There is no known workaround at this time.

Resolution

All OpenSSH users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-misc/openssh-4.2_p1-r1"

All Dropbear users should upgrade to the latest version:

Code Listing 3.2: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-misc/dropbear-0.47-r1"

4. References

CVE-2006-0225

Page updated February 20, 2006

Summary: This is a Gentoo Linux Security Advisory

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