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Category:  Application (Generic)  >  Squid Vendors:  [Multiple Authors/Vendors]
Squid Proxy Caching Server Heap Overflow in Processing Compressed DNS Responses Could Allow Remote DNS Servers to Crash the Service
SecurityTracker Alert ID:  1003896
CVE Reference:  GENERIC-MAP-NOMATCH   (Links to External Site)
Date:  Mar 26 2002
Impact:  Denial of service via network
Fix Available:  Yes   Vendor Confirmed:  Yes  
Version(s): Squid-2.x up to and including 2.4.STABLE4
Description:  A denial of service vulnerability was reported in the Squid proxy caching server. A remote user with control of a DNS server could cause the service to crash.

It is reported that certain error and boundary conditions are not checked when handling compressed DNS answer messages in the internal DNS code (lib/rfc1035.c). A remote user with a malicous DNS server could craft a DNS reply that causes Squid to exit with a SIGSEGV.

It is reported that the affected code exists in Squid-2.3, Squid-2.4, Squid-2.5 and Squid-2.6/Squid-HEAD, and is enabled by default.

The vendor notes that this vulnerability was reported by zen-parse.

Impact:  A remote user with control of a DNS server could send a DNS response message that could trigger a heap buffer overflow in the Squid server, causing the Squid service to crash.
Solution:  The vendor has released a fixed version (Squid-2.4.STABLE6), available at:

ftp://ftp.squid-cache.org/pub/squid-2/STABLE/
http://www.squid-cache.org/Versions/v2/2.4/

The vendor has also provided the following workaround:

"Squid-2.4, Squid-2.5 and Squid-2.6/Squid-HEAD can be recompiled to use the external DNS server support by running configure with the --disable-internal-dns option. There is no run-time configuration option to select between the internal/external DNS code.

We recommend that you upgrade, rather than simply switch to external DNS lookups. The external DNS implementation uses child processes and may negatively affect Squid's performance, especially for busy caches."

Vendor URL:  www.squid-cache.org/Advisories/SQUID-2002_2.txt (Links to External Site)
Cause:  Boundary error
Underlying OS:  Linux (Any), UNIX (Any)

Message History:   This archive entry has one or more follow-up message(s) listed below.
Mar 26 2002 (FreeBSD Issues Fix) Squid Proxy Caching Server Heap Overflow in Processing Compressed DNS Responses Could Allow Remote DNS Servers to Crash the Service   (FreeBSD Security Advisories <security-advisories@FreeBSD.ORG>)
The vendor has released a fix.
Apr 16 2002 (Mandrake Issues Fix) Squid Proxy Caching Server Heap Overflow in Processing Compressed DNS Responses Could Allow Remote DNS Servers to Crash the Service   (Mandrake Linux Security Team <security@linux-mandrake.com>)
The vendor has released a fix.
Apr 26 2002 (Caldera Issues Fix for OpenLinux Server)Re: Squid Proxy Caching Server Heap Overflow in Processing Compressed DNS Responses Could Allow Remote DNS Servers to Crash the Service   (security@caldera.com)
Caldera has released a fix for OpenLinux Server 3.x.
Jun 17 2002 (Caldera Issues Fix for OpenServer) Squid Proxy Caching Server Heap Overflow in Processing Compressed DNS Responses Could Allow Remote DNS Servers to Crash the Service   (security@caldera.com)
Caldera (SCO) has released a fix for OpenServer.



 Source Message Contents

Date:  Tue, 26 Mar 2002 14:51:25 -0500
Subject:  Squid Proxy Cache Security Update Advisory SQUID-2002:2

 

This is a multi-part message in MIME format.
--------------010B64A7738FD3F4E40AA95C
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

http://www.squid-cache.org/Advisories/SQUID-2002_2.txt
--------------010B64A7738FD3F4E40AA95C
Content-Type: text/plain; charset=us-ascii;
 name="SQUID-2002_2.txt"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="SQUID-2002_2.txt"

__________________________________________________________________

      Squid Proxy Cache Security Update Advisory SQUID-2002:2
__________________________________________________________________

Advisory ID:            SQUID-2002:2
Date:                   March 26, 2002
Affected versions:      Squid-2.x up to and including 2.4.STABLE4
Reported by:            zen-parse <zen-parse@gmx.net>
__________________________________________________________________

       http://www.squid-cache.org/Advisories/SQUID-2002_2.txt
__________________________________________________________________

Problem Description:
 A security issue has recently been found and fixed in the Squid-2.X
 releases up to and including 2.4.STABLE4.

 Error and boundary conditions were not checked when handling
 compressed DNS answer messages in the internal DNS code (lib/rfc1035.c).
 A malicous DNS server could craft a DNS reply that causes Squid
 to exit with a SIGSEGV.

 The relevant code exists in Squid-2.3, Squid-2.4, Squid-2.5 and
 Squid-2.6/Squid-HEAD, and is enabled by default.

__________________________________________________________________

Updated Packages:

 The Squid-2.4.STABLE6 release contains fixes for all these
 problems. You can download the Squid-2.4.STABLE6 release from

   ftp://ftp.squid-cache.org/pub/squid-2/STABLE/
   http://www.squid-cache.org/Versions/v2/2.4/

 or the mirrors (may take a while before all mirrors are updated).
 For a list of mirror sites see

   http://www.squid-cache.org/Mirrors/ftp-mirrors.html
   http://www.squid-cache.org/Mirrors/http-mirrors.html
   
 Individual patches to the mentioned issues can be found from our
 patch archive for version Squid-2.4.STABLE4

   http://www.squid-cache.org/Versions/v2/2.4/bugs/

 The patches should also apply with only a minimal effort to
 earlier Squid 2.4 versions if required.

 The Squid-2.5 and Squid-2.6/Squid-HEAD nightly snapshots contains
 the fixed DNS code.

__________________________________________________________________

Determining if your are vulnerable:

 You are vulnerable if you are running these versions of Squid
 with internal DNS queries:

 * Squid-2.4 version up to and including Squid-2.4.STABLE4
 * Squid-2.5 up to the fix date (Tuesday, March 12 2002 UTC)
 * Squid-2.6 / Squid-HEAD up to the fix date
   (Tuesday, March 12 2002 UTC)
 * Squid-2.3

 Squid uses the internal DNS implementation by default, and
 prints a line like this in cache.log when it is in use:

   DNS Socket created at 0.0.0.0, port 4345, FD 5

__________________________________________________________________

Workarounds:

 Squid-2.4, Squid-2.5 and Squid-2.6/Squid-HEAD can be recompiled
 to use the external DNS server support by running configure with
 the --disable-internal-dns option. There is no run-time configuration
 option to select between the internal/external DNS code.

 We recommend that you upgrade, rather than simply switch to external
 DNS lookups.  The external DNS implementation uses child processes
 and may negatively affect Squid's performance, especially for busy
 caches.

__________________________________________________________________
END

--------------010B64A7738FD3F4E40AA95C--



 


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