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OpenSSH, Dropbear: Insecure use of system() call

Content:

1.  Gentoo Linux Security Advisory

Version Information

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



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Page updated February 20, 2006

Summary: This is a Gentoo Linux Security Advisory

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