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If through a vulnerability assessment, a network security issue is detected for the vulnerability below, applying the appropriate security patches in a timely matter is very important.  If you have detected that your system has already been compromised, following CERT's Network Security recovery document will assist with recommended steps for system recovery.

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OpenSSH Reverse DNS Lookup bypass

Vulnerability Assessment Summary Checks for the remote SSH version Detailed Explanation for this Vulnerability Assessment You are running OpenSSH-portable 3.6.1 or older. There is a flaw in this version which may permit a possible hacker to bypass the access controls set by the administrator of this server. OpenSSH features a mechanism which can restrict the list of hosts a given user can log from by specifying a pattern in the user key file (ie: *.mynetwork.com would let a user connect only from the local network). However there is a flaw in the way OpenSSH does reverse DNS lookups. If a possible hacker configures his DNS server to send a numeric IP address when a reverse lookup is performed, he may be able to circumvent this mechanism. Solution : Upgrade to OpenSSH 3.6.2 when it comes out Network Security Threat Level: Low Networks Security ID: 7831 Vulnerability Assessment Copyright: This script is Copyright (C) 2003-2006 Tenable Network Security

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