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[dotnet] taint propagation errors / regressions #21581
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Hello, I'm playing with deserilization vulnerabilities and I found an error where a test case already exist, however I think it's not properly handling the case. I just added a variable assignment and the taint stop in the constructor: [WebMethod]
public void UpdateConfiguration2(string data)
{
var ds = new BinaryFormatter();
// BAD
MemoryStream ms = new MemoryStream(Convert.FromBase64String(data))
ds.Deserialize(ms); // $ Alert[cs/unsafe-deserialization-untrusted-input]
}
Here is the original test case: class BadBinaryFormatter2
{
public static object Deserialize(TextBox type, TextBox data)
{
var ds = new BinaryFormatter();
// BAD
return ds.Deserialize(new MemoryStream(Convert.FromBase64String(data.Text))); // $ Alert[cs/unsafe-deserialization-untrusted-input]
}
}Some changes were made in some summary models for example in the method - ["System", "Convert", False, "FromBase64String", "(System.String)", "", "Argument[0]", "ReturnValue", "taint", "manual"]Before it was this ( - ["System", "Convert", False, "FromBase64String", "(System.String)", "", "Argument[0]", "ReturnValue.Element", "taint", "manual"]Here is the summaryModel for - ["System.IO", "MemoryStream", False, "MemoryStream", "(System.Byte[])", "", "Argument[0].Element", "Argument[this]", "taint", "manual"]It reminds me another problem that we already discuss so I don't know if it's linked: #19911 This Here is my query: /**
* @name Forward Partial Dataflow
* @description Forward Partial Dataflow
* @kind path-problem
* @precision low
* @problem.severity error
* @id githubsecuritylab/forward-partial-dataflow
* @tags template
*/
import csharp
import semmle.code.csharp.dataflow.TaintTracking
import PartialFlow::PartialPathGraph
import semmle.code.csharp.dataflow.flowsources.Remote
private module MyConfig implements DataFlow::ConfigSig {
predicate isSource(DataFlow::Node source) {
exists(Parameter p |
p.hasName("data") and
p.getCallable().hasName(["UpdateConfiguration2", "Deserialize"]) and
source.asParameter() = p
)
}
predicate isSink(DataFlow::Node sink) { none() }
predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
exists(MemberAccess ma |
// node2 is the reading of the field
ma = node2.asExpr() and
// node1 is the object being accessed
ma.getQualifier() = node1.asExpr()
)
}
}
private module MyFlow = TaintTracking::Global<MyConfig>; // or DataFlow::Global<..>
int explorationLimit() { result = 10 }
private module PartialFlow = MyFlow::FlowExplorationFwd<explorationLimit/0>;
from PartialFlow::PartialPathNode source, PartialFlow::PartialPathNode sink
where PartialFlow::partialFlow(source, sink, _)
select sink.getNode(), source, sink, "This node receives taint from $@.", source.getNode(),
"this source"Thank you :) |
Replies: 1 comment 2 replies
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My imports are missing and CodeQL didn't find |
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no worries! Thanks for coming back to this, I was about to launch an investigation 🙂 glad you managed to sort it out! |
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If you have time to look at this one #21567 I would appreciate :) |
My imports are missing and CodeQL didn't find
MemoryStreamit's my fault sorry for the spam :)