Additional information is available that describes the BREACH exploit tool that an attacker could use to access sensitive information.
A presentation by security researchers will describe how an attacker could use the BREACH exploit tool to exploit weakness in the HTTP compression mechanism.
An attacker could use the BREACH tool to retrieve session identifiers, CSRF tokens, OAuth tokens, email addresses, and other fields from an HTTPS channel. Although the BREACH tool could allow security professionals to determine levels of exposure and deploy protections against this new attack vector, the BREACH tool may also be used for malicious intent that could allow an attacker to access sensitive information.
BREACH is known to exploit an attacker's ability to observe the length of compressed HTTP responses. An attacker could use the information gathered from the length size of compressed HTTP responses, along with sending crafted HTTPS requests to a targeted site, to guess a secret character by character in an HTTP response body.
US-CERT has released a vulnerability note at the following link: VU#987798
Administrators may consider disabling HTTP compression on targeted sites or systems.
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.
The security vulnerability applies to the following combinations of products.
Security Activity Bulletin
Original Release Base
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.
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.