Generic XPath Injection Vulnerability Scanner

Generic web applications and services often use XML data stores or XML-based configuration and query mechanisms. These systems are commonly deployed to process user-supplied parameters for search, authentication, or configuration lookups. Developers and integrators typically rely on XPath expressions to retrieve or filter nodes from XML documents within application logic or middleware. Many frameworks provide XPath capabilities in server-side code, and when user input is inserted into XPath expressions without proper sanitization it becomes a risk vector. Security teams and automated scanners use targeted checks to identify whether application endpoints accept input that influences XPath queries. Detecting XPath injection early helps prevent data leakage and unauthorized query manipulation.

XPath Injection is an input-based injection flaw where attacker-controlled data is embedded into an XPath expression, changing its intended logic. When applications build XPath queries by concatenating unsanitized input, attackers can craft payloads that alter node selection, bypass authentication checks, or retrieve confidential XML nodes. The vulnerability can be subtle because XPath syntax differs from SQL, but impact is comparable - unauthorized data access, logic bypass, or disclosure of application internals. Successful exploitation typically requires the application to parse XML and to construct XPath queries using user-controllable fields such as username, id, or search parameters. Attackers may exploit blind or error-based behaviors to confirm injection and enumerate sensitive XML content. Proper detection helps developers apply input validation and safe query construction patterns to mitigate the risk.

Technically, the vulnerable endpoint accepts one or more parameters that are interpolated directly into an XPath expression on the server. Common vulnerable endpoints include login routines that verify credentials against XML files (for example, //user[username/text()='{user}' and password/text()='{pass}']) or search APIs that build queries like //product[name[contains(.,'{q}')]]. When an application fails to escape quotes or does not use parameterized XPath APIs, an attacker can inject boolean constructs (e.g., ' or '1'='1) or XPath functions to alter results. Some payloads exploit union-like constructs or use string concatenation, predicate manipulation, and functions like text() or contains() to reveal nodes. Error messages or timing differences can be leveraged for blind and time-based extraction of XML data. Detailed testing involves varying payloads, quoting strategies, and encoding styles to detect and exploit the injection point.

If exploited, an attacker may bypass authentication checks that rely on XPath, retrieve sensitive data contained in XML files (credentials, configuration values, or application secrets), or cause application logic to return unintended results. In certain implementations, attackers can enumerate node names and structure through iterative probes, leading to full disclosure of the XML data model. Business logic may be subverted by returning false or manipulated results, which can cascade into authorization bypass or data corruption. Even where direct sensitive data is not present, attackers can use XPath injection to infer system structure and identify additional attack vectors. Combined with other flaws, XPath injection can materially increase the impact of an intrusion.

REFERENCES

• https://owasp.org/www-community/attacks/XPath_Injection
• https://cwe.mitre.org/data/definitions/91.html