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codeql/javascript/ql/examples/queries/dataflow/DecodingAfterSanitization/DecodingAfterSanitizationGeneralized.ql
2023-10-13 13:15:03 +02:00

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/**
* @name Decoding after sanitization (generalized)
* @description Tracks the return value of an HTML sanitizer into an escape-sequence decoder,
* indicating an ineffective sanitization attempt.
* @kind path-problem
* @problem.severity error
* @tags security
* @id js/examples/decoding-after-sanitization-generalized
*/
import javascript
/**
* A call to a function that may introduce HTML meta-characters by
* replacing `%3C` or `\u003C` with `<`.
*/
class DecodingCall extends DataFlow::CallNode {
string kind;
DataFlow::Node input;
DecodingCall() {
this.getCalleeName().matches("decodeURI%") and
input = this.getArgument(0) and
kind = "URI decoding"
or
input = this.(JsonParserCall).getInput() and
kind = "JSON parsing"
}
/** Gets the decoder kind, to be used in the alert message. */
string getKind() { result = kind }
/** Gets the input being decoded. */
DataFlow::Node getInput() { result = input }
}
module DecodingAfterSanitizationConfig implements DataFlow::ConfigSig {
predicate isSource(DataFlow::Node node) { node instanceof HtmlSanitizerCall }
predicate isSink(DataFlow::Node node) { node = any(DecodingCall c).getInput() }
}
module DecodingAfterSanitizationFlow = TaintTracking::Global<DecodingAfterSanitizationConfig>;
import DecodingAfterSanitizationFlow::PathGraph
from
DecodingAfterSanitizationFlow::PathNode source, DecodingAfterSanitizationFlow::PathNode sink,
DecodingCall decoder
where
DecodingAfterSanitizationFlow::flowPath(source, sink) and
decoder.getInput() = sink.getNode()
select sink.getNode(), source, sink, decoder.getKind() + " invalidates $@.", source.getNode(),
"this HTML sanitization"