An adversary leverages the capability to execute their own script by embedding it within other scripts that the target software is likely to execute due to programs' vulnerabilities that are brought on by allowing remote hosts to execute scripts.
Likelihood Of Attack
This table shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf and ParentOf, and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as CanFollow, PeerOf, and CanAlsoBe are defined to show similar attack patterns that the user may want to explore.
Meta Attack Pattern - A meta level attack pattern in CAPEC is a decidedly abstract characterization of a specific methodology or technique used in an attack. A meta attack pattern is often void of a specific technology or implementation and is meant to provide an understanding of a high level approach. A meta level attack pattern is a generalization of related group of standard level attack patterns. Meta level attack patterns are particularly useful for architecture and design level threat modeling exercises.
Spider: Using a browser or an automated tool, an adversary records all entry points for inputs that happen to be reflected in a client-side script element. These script elements can be located in the HTML content (head, body, comments), in an HTML tag, XML, CSS, etc.
Use a spidering tool to follow and record all non-static links that are likely to have input parameters (through forms, URL, fragments, etc.) actively used by the Web application.
Use a proxy tool to record all links visited during a manual traversal of the web application.
Use a browser to manually explore the website and analyze how it is constructed. Many browsers' plugins are available to facilitate the analysis or automate the discovery.
Probe identified potential entry points for XSS vulnerability: The adversary uses the entry points gathered in the "Explore" phase as a target list and injects various common script payloads to determine if an entry point actually represents a vulnerability and to characterize the extent to which the vulnerability can be exploited.
Manually inject various script payloads into each identified entry point using a list of common script injection probes that typically work in a client-side script elements context and observe system behavior to determine if script was executed.
Manually inject various script payloads into each identified entry point using a list of common script injection probes that typically work in a server-side script elements context and observe system behavior to determine if script was executed.
Use an automated injection attack tool to inject various script payloads into each identified entry point using a list of common script injection probes that typically work in a client-side script elements context and observe system behavior to determine if script was executed.
Use an automated injection attack tool to inject various script payloads into each identified entry point using a list of common script injection probes that typically work in a server-side script elements context and observe system behavior to determine if script was executed.
Use a proxy tool to record results of the created requests.
Steal session IDs, credentials, page content, etc.: As the adversary succeeds in exploiting the vulnerability, they can choose to steal user's credentials in order to reuse or to analyze them later on.
Forceful browsing: When the adversary targets the current application or another one (through CSRF vulnerabilities), the user will then be the one who perform the attacks without being aware of it. These attacks are mostly targeting application logic flaws, but it can also be used to create a widespread attack against a particular website on the user's current network (Internet or not).
Content spoofing: By manipulating the content, the adversary targets the information that the user would like to get from the website.
Target software must be able to execute scripts, and also grant the adversary privilege to write/upload scripts.
To load malicious script into open, e.g. world writable directory
Executing remote scripts on host and collecting output
This table specifies different individual consequences associated with the attack pattern. The Scope identifies the security property that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in their attack. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a pattern will be used to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Execute Unauthorized Commands
Use browser technologies that do not allow client side scripting.
Utilize strict type, character, and encoding enforcement.
Server side developers should not proxy content via XHR or other means. If a HTTP proxy for remote content is setup on the server side, the client's browser has no way of discerning where the data is originating from.
Ensure all content that is delivered to client is sanitized against an acceptable content specification.
Perform input validation for all remote content.
Perform output validation for all remote content.
Session tokens for specific host
Patching software. There are many attack vectors for XSS on the client side and the server side. Many vulnerabilities are fixed in service packs for browser, web servers, and plug in technologies, staying current on patch release that deal with XSS countermeasures mitigates this.
Privileges are constrained, if a script is loaded, ensure system runs in chroot jail or other limited authority mode
The XSS script that is embedded in a given IMG tag can be manipulated to probe a different address on every click of the mouse or other motions that the Ajax application is aware of.
In addition the enumerations allow for the adversary to nest sequential logic in the attacks. While Ajax applications do not open up brand new attack vectors, the existing attack vectors are more than adequate to execute attacks, and now these attacks can be optimized to sequentially execute and enumerate host environments.
~/.bash_profile and ~/.bashrc are executed in a user's context when a new shell opens or when a user logs in so that their environment is set correctly. ~/.bash_profile is executed for login shells and ~/.bashrc is executed for interactive non-login shells. This means that when a user logs in (via username and password) to the console (either locally or remotely via something like SSH), ~/.bash_profile is executed before the initial command prompt is returned to the user. After that, every time a new shell is opened, ~/.bashrc is executed. This allows users more fine grained control over when they want certain commands executed. These files are meant to be written to by the local user to configure their own environment; however, adversaries can also insert code into these files to gain persistence each time a user logs in or opens a new shell.
A Related Weakness relationship associates a weakness with this attack pattern. Each association implies a weakness that must exist for a given attack to be successful. If multiple weaknesses are associated with the attack pattern, then any of the weaknesses (but not necessarily all) may be present for the attack to be successful. Each related weakness is identified by a CWE identifier.