Bug 62198 (CVE-2004-0918)

Summary:	VUL-0: CVE-2004-0918: squid SNMP module remote denial of service
Product:	[Novell Products] SUSE Security Incidents	Reporter:	Ludwig Nussel <lnussel>
Component:	Incidents	Assignee:	Security Team bot <security-team>
Status:	RESOLVED FIXED	QA Contact:	Security Team bot <security-team>
Severity:	Normal
Priority:	P3 - Medium	CC:	security-team
Version:	unspecified
Target Milestone:	---
Hardware:	All
OS:	Linux
Whiteboard:	CVE-2004-0918: CVSS v2 Base Score: 5.0 (AV:N/AC:L/Au:N/C:N/I:N/A:P)
Found By:	---	Services Priority:
Business Priority:		Blocker:	---
Marketing QA Status:	---	IT Deployment:	---
Attachments:	squid.patch.maintained squid.patch.box

Description Marcus Meissner 2004-10-13 23:12:58 UTC

Delivered-To: mailing list squid-announce@squid-cache.org                        
Delivered-To: moderator for squid-announce@squid-cache.org                       
Subject: iDEFENSE Security Advisory 10.11.04: Squid Web Proxy Cache Remote       
+Denial of Service Vulnerability                                                 
Date: Tue, 12 Oct 2004 10:08:38 -0400                                            
Message-ID: <FB24803D1DF2A34FA59FC157B77C9705035C3D13@idserv04.idef.com>         
From: Pedram Amini <pamini@iDefense.com>                                         
To: squid-bugs@squid-cache.org                                                   
Cc: squid-announce@squid-cache.org                                               

Squid Web Proxy Cache Remote Denial of Service Vulnerability                     

iDEFENSE Security Advisory 10.11.04:                                             
www.idefense.com/application/poi/display?id=152&type=vulnerabilities             
October 11, 2004                                                                 

I. BACKGROUND                                                                    

Squid Web Proxy Cache is a full-featured web proxy cache designed to run         
on Unix systems. It supports proxying HTTP, FTP, SSL, DNS, and has               
support for SNMP.                                                                

II. DESCRIPTION                                                                  

Remote exploitation of a design error in the SNMP module of Squid Web            
Proxy Cache may lead to a denial of service.                                     

The problem specifically exists due to an ASN1 parsing error where               
certain header length combinations can slip through the validations              
performed by the ASN1 parser, eventually causing the server to restart           
and close all current connections. The server takes several seconds to           
restart.                                                                         

The offending code is in the asn_parse_header() routine of                       
snmplib/asn1.c, which under some cases will allow negative length fields         
to pass validation. This leads to a failed xmalloc(), and the server             
then assumes there is heap corruption or some other exceptional                  
condition, and restarts.                                                         

III. ANALYSIS                                                                    

An attacker can exploit the above-described vulnerability to crash a             
Squid server. If the attack is repeated, it can render the server                
useless. Only a single UDP packet is required to trigger this                    
vulnerability, so the source address can be spoofed.                             

IV. DETECTION           
             iDEFENSE has confirmed the existence of this vulnerability in 
Squid Web          
Proxy Cache version 2.5-STABLE5 compiled with SNMP support as well as            
Squid Web Proxy Cache version 3.0-PRE3-20040702 compiled with SNMP               
support. It is suspected that earlier versions are vulnerable as well.           

To find if a Squid binary is compiled with SNMP support one can run:             

    grep snmp_port /usr/local/squid/sbin/squid                                   

If this command returns silently, that binary was not built with SNMP            
support and it is not vulnerable to this issue.                                  

V. WORKAROUND                                                                    

Disable SNMP support or filter the port that has SNMP processing                 
activated (3401 by default) to allow only SNMP data from trusted hosts.          

To disable SNMP support on a squid binary that has SNMP support compiled         
in, use the entry snmp_port 0 in the squid.conf configuration file.              

To allow only the local interface to process SNMP, use the entry                 
"snmp_incoming_address 127.0.0.1" in the squid.conf configuration file.          

Squid must be restarted to activate changes in the configuration file.           

VI. VENDOR RESPONSE                                                              

Patch relative to Squid-2.5.STABLE6:                                             

http://www.squid-cache.org/Versions/v2/2.5/bugs/squid-2.5.STABLE6-SNMP_c         
ore_dump.patch                                                                   

Squid-2.5.STABLE7 release:                                                       

   ftp://ftp.squid-cache.org/pub/squid-2/STABLE/squid-2.5.STABLE7.tar.gz         

ftp://ftp.squid-cache.org/pub/squid-2/STABLE/squid-2.5.STABLE7.tar.bz2           
   http://www.squid-cache.org/Versions/v2/2.5/squid-2.5.STABLE7.tar.gz           
   http://www.squid-cache.org/Versions/v2/2.5/squid-2.5.STABLE7.tar.bz2          

or any of the mirrors                                                            

   http://www.squid-cache.org/Mirrors/ftp-mirrors.html                           
   http://www.squid-cache.org/Mirrors/http-mirrors.html                          

VII. CVE INFORMATION                                                             

The Common Vulnerabilities and Exposures (CVE) project has assigned the          
names CAN-2004-0918 to these issues. This is a candidate for inclusion           
in the CVE list (http://cve.mitre.org), which standardizes names for             
security problems.                                                               

VIII. DISCLOSURE TIMELINE                                                        

09/15/2004  Initial vendor notification                                          
09/15/2004  iDEFENSE clients notified                                            
09/15/2004  Initial vendor response     
                                        10/05/2004  Coordinated public 
disclosure                                        

IX. CREDIT                                                                       

The discoverer of this vulnerability wishes to remain anonymous.                 

Get paid for vulnerability research                                              
http://www.idefense.com/poi/teams/vcp.jsp                                        

X. LEGAL NOTICES                                                                 

Copyright 2004 iDEFENSE, Inc.                                                    

Permission is granted for the redistribution of this alert                       
electronically. It may not be edited in any way without the express              
written consent of iDEFENSE. If you wish to reprint the whole or any             
part of this alert in any other medium other than electronically, please         
email customerservice@idefense.com for permission.                               

Disclaimer: The information in the advisory is believed to be accurate           
at the time of publishing based on currently available information. Use          
of the information constitutes acceptance for use in an AS IS condition.         
There are no warranties with regard to this information. Neither the             
author nor the publisher accepts any liability for any direct, indirect,         
or consequential loss or damage arising from use of, or reliance on,             
this information.

Comment 1 Marcus Meissner 2004-10-13 23:12:59 UTC

<!-- SBZ_reproduce  -->
n/a

Comment 2 Klaus Singvogel 2004-10-14 21:15:13 UTC

fixed packages submited for: 9.2, 9.1/SLES9, 9.0, 8.2, 8.1/SLES8/UL 
 
Test-Team: 
didn't test anything, but upstream patch run in flawless and builds fine. 
 
Security-Team: 
please handle rest of update process: patchinfo, putonftp... - Thanks in 
advance.

Comment 3 Ludwig Nussel 2004-10-14 21:18:54 UTC

<!-- SBZ_reopen -->Reopened by lnussel@suse.de at Thu Oct 14 15:18:54 2004, took initial reporter meissner@suse.de to cc

Comment 4 Ludwig Nussel 2004-10-14 21:18:54 UTC

reopen for reassign

Comment 5 Ludwig Nussel 2004-10-15 20:00:15 UTC

For the record. SNMP is not enabled in the default config, correct?

Comment 6 Klaus Singvogel 2004-10-18 18:02:58 UTC

Ludwig: you are wrong. Its enabled per default, as it is very useful. 
 
But if I understand the problem correct, then the vulnerability is present as 
soon as SNMP is compiled in (see above: "IV. DETECTION"). This is the case for 
all of our versions.

Comment 7 Ludwig Nussel 2004-10-18 19:01:46 UTC

Created attachment 25118 [details]
squid.patch.maintained

Comment 8 Ludwig Nussel 2004-10-18 19:02:01 UTC

Created attachment 25119 [details]
squid.patch.box

Comment 9 Marcus Meissner 2004-10-26 23:35:37 UTC

updates released.

Comment 10 Thomas Biege 2009-10-13 19:53:41 UTC

CVE-2004-0918: CVSS v2 Base Score: 5.0 (AV:N/AC:L/Au:N/C:N/I:N/A:P)