Red Hat has released a security advisory and updated packages to address the Squid Web Proxy Cache string.cci remote denial of service vulnerability.
Description
Squid Web Proxy Cache versions prior to 3.1.8 contain a vulnerability that could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on the targeted system.
The vulnerability is due to a memory corruption error in the affected software while handling HTTP requests. An authenticated, remote attacker could exploit the vulnerability by sending crafted requests to the affected system. Processing these requests could cause a pointer dereference error, corrupting memory. The memory corruption could cause an unexpected termination of the application, denying service to legitimate users.
Squid has confirmed the vulnerability and released updated software.
Warning Indicators
Squid Web Proxy Cache versions prior to 3.1.8 are vulnerable.
IntelliShield Analysis
To exploit the vulnerability, an attacker needs to be authenticated to the system, which somewhat reduces the likelihood of an attack.
Reports suggest that binaries built with --disable-http-violations are not vulnerable. Squid versions where the squid.conf file is configured with the ignore_expect_100 on directive are vulnerable. Additional Squid development versions prior to 3.2.0.8 are also vulnerable.
A successful exploit could lead to a DoS condition in the context of the affected service only. Restarting the service will resume normal operation of the vulnerable software.
The vulnerability could be triggered accidentally by client browser applications that reference Squid. The vendor has confirmed that applications that may trigger accidental exploits exist publicly.
Vendor Announcements
Squid has released a security advisory at the following link: SQUID-2010:3
Red Hat has released a security advisory at the following link: RHSA-2011:0545
Impact
An authenticated, remote attacker could exploit this vulnerability to cause a DoS condition, causing the application to terminate unexpectedly and deny access to legitimate users.
Technical Information
The vulnerability is in the strcmp() function in the string.cci source file of the affected software due to a memory error while handling HTTP requests. An authenticated, remote attacker could exploit the vulnerability by transmitting crafted HTTP requests to the affected software. This could trigger a NULL pointer dereference error, causing the affected service to crash and resulting in a DoS condition.
Safeguards
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators are advised to implement an intrusion prevention system (IPS) or intrusion detection system (IDS) to help detect and prevent attacks that attempt to exploit this vulnerability.
Administrators are advised to configure the Squid instance with --disable-http-violations.
Administrators are advised to monitor affected systems.
Patches/Software
Squid has released updated software at the following link: 3.1.8
Version 1, September 27, 2010, 8:25 AM: Squid Web Proxy Cache contains a vulnerability that could allow an authenticated, remote attacker to cause a denial of service condition on the targeted system. Updates are available.
The security vulnerability applies to the following combinations of products.
Primary Products:
Duane Wessels
Squid Web Proxy Cache
3.1 .1, .2, .3, .4, .5, .5.1, .6, .7
Associated Products:
FreeBSD Project
FreeBSD
6.3 Base | 6.4 Base | 7.0 Base | 7.1 Base | 7.2 Base | 7.3 Base | 8.0 Base
Red Hat, Inc.
Red Hat Enterprise Linux Server
6 IA-32, PPC, s390x, x86_64
Red Hat, Inc.
Red Hat Enterprise Linux Workstation
6 IA-32, x86_64
Alerts and bulletins on the Cisco Security Intelligence Operations Portal are highlighted by analysts in the
Cisco Threat Operations Center and represent a subset of the comprehensive content that is available through Cisco Security IntelliShield Alert Manager Service.
This customizable threat and vulnerability alert service provides security staff with access to timely, accurate, and credible information about threats and vulnerabilities that may affect their environment. Cisco is pleased to offer a free trial of the service.
To register for full access, please visit the IntelliShield trial registration page.
LEGAL DISCLAIMER The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.
