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Home >> Browse Vulnerability Assessment Database >> Misc. >> OpenSSH Reverse DNS Lookup bypass


Vulnerability Assessment Details

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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