CAPEC-31 Accessing/Intercepting/Modifying HTTP Cookies

This attack relies on the use of HTTP Cookies to store credentials, state information and other critical data on client systems. There are several different forms of this attack. The first form of this attack involves accessing HTTP Cookies to mine for potentially sensitive data contained therein. The second form involves intercepting this data as it is transmitted from client to server. This intercepted information is then used by the adversary to impersonate the remote user/session. The third form is when the cookie's content is modified by the adversary before it is sent back to the server. Here the adversary seeks to convince the target server to operate on this falsified information.

1. [Explore] [Obtain copy of cookie] The adversary first needs to obtain a copy of the cookie. The adversary may be a legitimate end user wanting to escalate privilege, or could be somebody sniffing on a network to get a copy of HTTP cookies. 2. [Experiment] [Obtain sensitive information from cookie] The adversary may be able to get sensitive information from the cookie. The web application developers may have assumed that cookies are not accessible by end users, and thus, may have put potentially sensitive information in them. 3. [Experiment] [Modify cookie to subvert security controls.] The adversary may be able to modify or replace cookies to bypass security controls in the application.

• Target server software must be a HTTP daemon that relies on cookies. • The cookies must contain sensitive information. • The adversary must be able to make HTTP requests to the server, and the cookie must be contained in the reply.

• [Low] To overwrite session cookie data, and submit targeted attacks via HTTP • [High] Exploiting a remote buffer overflow generated by attack

• Confidentiality: Read Data • Integrity: Modify Data • Confidentiality, Access Control, Authorization: Gain Privileges

• Design: Use input validation for cookies • Design: Generate and validate MAC for cookies • Implementation: Use SSL/TLS to protect cookie in transit • Implementation: Ensure the web server implements all relevant security patches, many exploitable buffer overflows are fixed in patches issued for the software.