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Vulnerability of Slackware: denial of service via lastlog/faillog

Synthesis of the vulnerability 

On Slackware, a local attacker can use the lastlog/faillog commands, in order to change limits, so the administrator cannot access to the system.
Vulnerable software: Slackware.
Severity of this announce: 1/4.
Creation date: 11/04/2011.
Références of this computer vulnerability: BID-47303, SSA:2011-101-01, VIGILANCE-VUL-10531.

Description of the vulnerability 

The lastlog command displays information about the last authentications of a user. The faillog command displays authentication errors.

These command also allow the administrator to define the maximal number of authentication failures, before locking an account.

However, on Slackware, all users can use this feature. A local attacker can thus define a low trial number, and then try to connect to an account, in order to lock it.

On Slackware, a local attacker can therefore use the lastlog/faillog commands, in order to change limits, so the administrator cannot access to the system.
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This computer weakness announce impacts software or systems such as Slackware.

Our Vigil@nce team determined that the severity of this security alert is low.

The trust level is of type confirmed by the editor, with an origin of user shell.

A proof of concept or an attack tool is available, so your teams have to process this alert. An attacker with a technician ability can exploit this vulnerability.

Solutions for this threat 

Slackware: new shadow packages.
New packages are available:
ftp://ftp.slackware.com/pub/slackware/slackware-13.1/patches/packages/shadow-4.1.4.3-i486-2_slack13.1.txz
ftp://ftp.slackware.com/pub/slackware/slackware64-13.1/patches/packages/shadow-4.1.4.3-x86_64-2_slack13.1.txz
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