9.8 CVE-2025-21613

An adversary manipulates the content of request parameters for the purpose of undermining the security of the target. Some parameter encodings use text characters as separators. For example, parameters in a HTTP GET message are encoded as name-value pairs separated by an ampersand (&). If an attacker can supply text strings that are used to fill in these parameters, then they can inject special characters used in the encoding scheme to add or modify parameters. For example, if user input is fed directly into an HTTP GET request and the user provides the value "myInput&new_param=myValue", then the input parameter is set to myInput, but a new parameter (new_param) is also added with a value of myValue. This can significantly change the meaning of the query that is processed by the server. Any encoding scheme where parameters are identified and separated by text characters is potentially vulnerable to this attack - the HTTP GET encoding used above is just one example.

An adversary takes advantage of improper data validation to inject malicious global parameters into a Flash file embedded within an HTML document. Flash files can leverage user-submitted data to configure the Flash document and access the embedding HTML document. [Spider] Using a browser or an automated tool, an adversary records all instances of HTML documents that have embedded Flash files. If there is an embedded Flash file, they list how to pass global parameters to the Flash file from the embedding object. [Determine the application susceptibility to Flash parameter injection] Determine the application susceptibility to Flash parameter injection. For each URL identified in the Explore phase, the adversary attempts to use various techniques such as DOM based, reflected, flashvars, and persistent attacks depending on the type of parameter passed to the embedded Flash file. [Execute Flash Parameter Injection Attack] Inject parameters into Flash file. Based on the results of the Experiment phase, the adversary crafts the underlying malicious URL containing injected Flash parameters and submits it to the web server. Once the web server receives the request, the embedding HTML document will controllable by the adversary.

This type of attack involves an attacker leveraging meta-characters in email headers to inject improper behavior into email programs. Email software has become increasingly sophisticated and feature-rich. In addition, email applications are ubiquitous and connected directly to the Web making them ideal targets to launch and propagate attacks. As the user demand for new functionality in email applications grows, they become more like browsers with complex rendering and plug in routines. As more email functionality is included and abstracted from the user, this creates opportunities for attackers. Virtually all email applications do not list email header information by default, however the email header contains valuable attacker vectors for the attacker to exploit particularly if the behavior of the email client application is known. Meta-characters are hidden from the user, but can contain scripts, enumerations, probes, and other attacks against the user's system. [Identify and characterize metacharacter-processing vulnerabilities in email headers] An attacker creates emails with headers containing various metacharacter-based malicious payloads in order to determine whether the target application processes the malicious content and in what manner it does so. An attacker leverages vulnerabilities identified during the Experiment Phase to inject malicious email headers and cause the targeted email application to exhibit behavior outside of its expected constraints.

An adversary adds duplicate HTTP GET/POST parameters by injecting query string delimiters. Via HPP it may be possible to override existing hardcoded HTTP parameters, modify the application behaviors, access and, potentially exploit, uncontrollable variables, and bypass input validation checkpoints and WAF rules. [Find User Input] The adversary finds anywhere in the web application that uses user-supplied input in a form or action. This can also be found by looking at parameters in the URL in the navigation bar of the browser [Add Duplicate Parameter Values] Once the adversary has identified what user input is used as HTTP parameters, they will add duplicates to each parameter one by one to observe the results. If the response from the HTTP request shows the duplicate parameter value concatenated with the original parameter value in some way, or simply just the duplicate parameter value, then HPP is possible. [Leverage HPP] Once the adversary has identified how the backend handles duplicate parameters, they will leverage this by polluting the paramters in a way that benefits them. In some cases, hardcoded parameters will be disregarded by the backend. In others, the adversary can bypass a WAF that might only check a parameter before it has been concatenated by the backend, resulting in malicious queries getting through.

In this type of an attack, an adversary injects operating system commands into existing application functions. An application that uses untrusted input to build command strings is vulnerable. An adversary can leverage OS command injection in an application to elevate privileges, execute arbitrary commands and compromise the underlying operating system. [Identify inputs for OS commands] The attacker determines user controllable input that gets passed as part of a command to the underlying operating system. [Survey the Application] The attacker surveys the target application, possibly as a valid and authenticated user [Vary inputs, looking for malicious results.] Depending on whether the application being exploited is a remote or local one the attacker crafts the appropriate malicious input, containing OS commands, to be passed to the application [Execute malicious commands] The attacker may steal information, install a back door access mechanism, elevate privileges or compromise the system in some other way.