COMMON ATTACK PATTERN ENUMERATION AND CLASSIFICATIONLive MITRE record
CAPEC-107
Cross Site Tracing
Cross Site Tracing (XST) enables an adversary to steal the victim's session cookie and possibly other authentication credentials transmitted in the header of the HTTP request when the victim's browser communicates to a destination system's web server.
Abstraction
Detailed
Typical severity
Very High
Likelihood of attack
Medium
Understand the attack
What is this attack pattern?
Cross Site Tracing (XST) enables an adversary to steal the victim's session cookie and possibly other authentication credentials transmitted in the header of the HTTP request when the victim's browser communicates to a destination system's web server.
Extended description
The adversary uses an XSS attack to have victim's browser sent an HTTP TRACE request to a destination web server, which will proceed to return a response to the victim's web browser that contains the original HTTP request in its body. Since the HTTP header of the original HTTP TRACE request had the victim's session cookie in it, that session cookie can now be picked off the HTTP TRACE response and sent to the adversary's malicious site. XST becomes relevant when direct access to the session cookie via the "document.cookie" object is disabled with the use of httpOnly attribute which ensures that the cookie can be transmitted in HTTP requests but cannot be accessed in other ways. Using SSL does not protect against XST. If the system with which the victim is interacting is susceptible to XSS, an adversary can exploit that weakness directly to get their malicious script to issue an HTTP TRACE request to the destination system's web server.
Execution flow
How does the attack proceed, step by step?
Explore
Determine if HTTP Trace is enabled
Determine if HTTP Trace is enabled at the web server with which the victim has an active session
Techniques used
- An adversary may issue an HTTP Trace request to the target web server and observe if the response arrives with the original request in the body of the response.
Experiment
Identify mechanism to launch HTTP Trace request
The adversary attempts to force the victim to issue an HTTP Trace request to the targeted application.
Techniques used
- The adversary probes for cross-site scripting vulnerabilities to force the victim into issuing an HTTP Trace request.
Exploit
Create a malicious script that pings the web server with HTTP TRACE request
The adversary creates a malicious script that will induce the victim's browser to issue an HTTP TRACE request to the destination system's web server. The script will further intercept the response from the web server, pick up sensitive information out of it, and forward to the site controlled by the adversary.
Techniques used
- The adversary's malicious script circumvents the httpOnly cookie attribute that prevents from hijacking the victim's session cookie directly using document.cookie and instead leverages the HTTP TRACE to catch this information from the header of the HTTP request once it is echoed back from the web server in the body of the HTTP TRACE response.
Execute malicious HTTP Trace launching script
The adversary leverages an XSS vulnerability to force the victim to execute the malicious HTTP Trace launching script
Intercept HTTP TRACE response
The adversary's script intercepts the HTTP TRACE response from teh web server, glance sensitive information from it, and forward that information to a server controlled by the adversary.
Requirements
What does the attack require?
Prerequisites
- HTTP TRACE is enabled on the web server
- The destination system is susceptible to XSS or an adversary can leverage some other weakness to bypass the same origin policy
- Scripting is enabled in the client's browser
- HTTP is used as the communication protocol between the server and the client
Skills required
- Medium: Understanding of the HTTP protocol and an ability to craft a malicious script
Resources required
- None: No specialized resources are required to execute this type of attack.
Impact
What does a successful attack lead to?
Read Data
Affected scopes: Confidentiality
Gain Privileges
Affected scopes: Confidentiality, Access Control, Authorization
Modify Data
Affected scopes: Integrity
Defence
How is it prevented and mitigated?
1
Administrators should disable support for HTTP TRACE at the destination's web server. Vendors should disable TRACE by default.
2
Patch web browser against known security origin policy bypass exploits.
Real world
MITRE example instances
Example instance 1Detail
An adversary determines that a particular system is vulnerable to reflected cross-site scripting (XSS) and endeavors to leverage this weakness to steal the victim's authentication cookie. An adversary realizes that since httpOnly attribute is set on the user's cookie, it is not possible to steal it directly with their malicious script. Instead, the adversary has their script use XMLHTTP ActiveX control in the victim's IE browser to issue an HTTP TRACE to the target system's server which has HTTP TRACE enabled. The original HTTP TRACE request contains the session cookie and so does the echoed response. The adversary picks the session cookie from the body of HTTP TRACE response and ships it to the adversary. The adversary then uses the newly acquired victim's session cookie to impersonate the victim in the target system.
In the absence of an XSS weakness on the site with which the victim is interacting, an adversary can get the script to come from the site that they control and get it to execute in the victim's browser (if they can trick the victim's into visiting their malicious website or clicking on the link that they supplies). However, in that case, due to the same origin policy protection mechanism in the browser, the adversary's malicious script cannot directly issue an HTTP TRACE request to the destination system's web server because the malicious script did not originate at that domain. An adversary will then need to find a way to exploit another weakness that would enable them to circumvent the same origin policy protection.