Sudo contains a vulnerability that could allow a local attacker to overwrite arbitrary files on a targeted system.
The vulnerability is due to an insecure temporary file that is created by a script and used by the affected software. An unauthenticated, remote attacker could exploit the vulnerability by creating a symbolic link in the insecure temporary file, causing the application to overwrite arbitrary files. This could allow the attacker to execute arbitrary code via the files.
The vendor has not confirmed this vulnerability; however, third-party software updates are available.
Indicators of Compromise
Sudo versions 1.8.4p5 and prior are vulnerable.
The vulnerability exists because the postun uninstall script that is used by the affected software creates an insecure temporary file.
A local attacker with privileges to create a symlink could exploit this vulnerability to overwrite arbitrary files with the content of the /etc/nsswitch.conf file. The attacker could also manipulate the script to modify the /etc/nsswitch.conf file data, which could allow the attacker to execute arbitrary code via the overwritten files.
To exploit this vulnerability, the attacker must win a race condition between the removal of the file and its re-creation via touch. If the attacker is able to win, it could be possible to launch further attacks.
This attack is successful only while upgrading or uninstalling the sudo package installed on the targeted system.
Administrators are advised to contact the vendor regarding future updates and releases.
Administrators are advised to allow only trusted users to access local systems.
Administrators are advised to monitor affected systems.
Red Hat has released an official CVE statement and a security advisory for bug 844442 at the following links: CVE-2012-3440 and RHSA-2012:1149
VMware has re-released a security advisory at the following link: VMSA-2013-0007
CentOS packages can be updated using the up2date or yum command.
Red Hat has released updated software for registered subscribers at the following link: Red Hat Network
Red Hat packages can be updated on Red Hat Enterprise Linux versions 5 and later using the yum tool.
VMware has released updated software at the following links:
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Cisco Multivendor Vulnerability Alerts respond to vulnerabilities identified in third-party vendors' products. These alerts contain information compiled from diverse sources and provide comprehensive technical descriptions, objective analytical assessments, workarounds and practical safeguards, and links to vendor advisories and patches.