TCP Wrappers Libwrap0 Hosts.Deny Bypass Vulnerability

BID:25485

Info

TCP Wrappers Libwrap0 Hosts.Deny Bypass Vulnerability

Bugtraq ID: 25485
Class: Design Error
CVE:
Remote: Yes
Local: No
Published: Aug 30 2007 12:00AM
Updated: Sep 04 2007 09:11PM
Credit: Jamin W. Collins is credited with the discovery of this issue.
Vulnerable: Wietse Venema TCP Wrappers 7.6
Ubuntu Ubuntu Linux 7.04 sparc
Ubuntu Ubuntu Linux 7.04 powerpc
Ubuntu Ubuntu Linux 7.04 i386
Ubuntu Ubuntu Linux 7.04 amd64
Debian Linux 4.0
Not Vulnerable:

Discussion

TCP Wrappers Libwrap0 Hosts.Deny Bypass Vulnerability

TCP Wrappers is prone to a vulnerability that lets attackers bypass access control rules. This issue occurs because the 'daemon_or_port_match()' function fails to properly handle connections missing server socket details in the 'hosts.deny' file.

Successfully exploiting this issue allows attackers to bypass 'hosts.deny' rules, potentially aiding them in further network-based attacks.

TCP Wrappers implementations on a variety of operating platforms are vulnerable, including TCP Wrappers:libwrap0 shipped with Ubuntu 7.0.4 and TCP Wrappers:libwrap0 7.6.dbs-11 on Debian Linux. Other platforms may be affected as well.

Exploit / POC

TCP Wrappers Libwrap0 Hosts.Deny Bypass Vulnerability

Attackers use readily available network utilities to exploit this issue.

Solution / Fix

TCP Wrappers Libwrap0 Hosts.Deny Bypass Vulnerability

Solution:
Multiple vendors have addressed this issue with patches and upgrades. Please see the references for more information.

References

TCP Wrappers Libwrap0 Hosts.Deny Bypass Vulnerability

References:
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