FreeBSD Security Advisory

01十月06

FreeBSD-SA-06:22.openssh

一會兒 openssl, 一會兒 openssh .. 最近是怎樣 ?!

II. Problem Description

The CRC compensation attack detector in the sshd(8) daemon, upon receipt of duplicate blocks, uses CPU time cubic in the number of duplicate blocks received. [CVE-2006-4924]

A race condition exists in a signal handler used by the sshd(8) daemon to handle the LoginGraceTime option, which can potentially cause some cleanup routines to be executed multiple times. [CVE-2006-5051]

III. Impact

An attacker sending specially crafted packets to sshd(8) can cause a Denial of Service by using 100% of CPU time until a connection timeout occurs. Since this attack can be performed over multiple connections simultaneously, it is possible to cause up to MaxStartups (10 by default)
sshd processes to use all the CPU time they can obtain. [CVE-2006-4924]

The OpenSSH project believe that the race condition can lead to a Denial of Service or potentially remote code execution, but the FreeBSD Security Team has been unable to verify the exact impact. [CVE-2006-5051]

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