GeoTools is an open source Java library that provides tools for geospatial data. Prior to versions 31.2, 30.4, and 29.6, Remote Code Execution (RCE) is possible if an application uses certain GeoTools functionality to evaluate XPath expressions supplied by user input. Versions 31.2, 30.4, and 29.6 contain a fix for this issue. As a workaround, GeoTools can operate with reduced functionality by removing the gt-complex jar from ones application. As an example of the impact, application schema datastore would not function without the ability to use XPath expressions to query complex content. Alternatively, one may utilize a drop-in replacement GeoTools jar from SourceForge for versions 31.1, 30.3, 30.2, 29.2, 28.2, 27.5, 27.4, 26.7, 26.4, 25.2, and 24.0. These jars are for download only and are not available from maven central, intended to quickly provide a fix to affected applications.
Weakness
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes code syntax before using the input in a dynamic evaluation call (e.g. “eval”).
Potential Mitigations
- Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- Inputs should be decoded and canonicalized to the application’s current internal representation before being validated (CWE-180, CWE-181). Make sure that your application does not inadvertently decode the same input twice (CWE-174). Such errors could be used to bypass allowlist schemes by introducing dangerous inputs after they have been checked. Use libraries such as the OWASP ESAPI Canonicalization control.
- Consider performing repeated canonicalization until your input does not change any more. This will avoid double-decoding and similar scenarios, but it might inadvertently modify inputs that are allowed to contain properly-encoded dangerous content.
References