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From "Dario Amiri (JIRA)" <>
Subject [jira] [Created] (CXF-5390) AbstractSamlBase64InHandler goes into infinite loop when processing bad header value.
Date Fri, 15 Nov 2013 21:19:21 GMT
Dario Amiri created CXF-5390:

             Summary: AbstractSamlBase64InHandler goes into infinite loop when processing
bad header value.
                 Key: CXF-5390
             Project: CXF
          Issue Type: Bug
    Affects Versions: 2.7.3
         Environment: Linux or Mac, Karaf 2.3.1 container, CXF 2.7.3
            Reporter: Dario Amiri
            Priority: Critical

Let's say I protect my JAX-RS service using SamlHeaderInHandler. The service expects me to
include a valid deflate encoded (compressed) then base 64 encoded token in the Authorization
of my RESTful call like this:


However if instead of inserting a token, I insert the following string "invalid_grant" in
the Authrorization header like so:

SAML invalid_grant

The following will happen:
1. SamlHeaderInHandler splits the header into it's two parts and sends what it thinks is the
assertion (the "invalid_grant" string) AbstractSamlBase64InHandler.handleToken
2. AbstractSamlBase64InHandler.handleToken first base 64 decodes the string. This completes
with no error.
3. AbstractSamlBase64InHandler.handleToken then tries to inflate the assertion.

It is during this last step that CXF goes into an infinite loop. Here is the code involved:

        while (!inflater.finished()) {
            inputLen = inflater.inflate(input);
            if (!inflater.finished()) {
                inflatedToken = new byte[input.length + inflatedLen];
                System.arraycopy(input, 0, inflatedToken, inflatedLen, inputLen);
                inflatedLen += inputLen;

When the input is the following byte array:

[94, -27, -122, 110, 16, 59, 41, 43, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

(which is the result from base 64 decoding the string "invalid_grant")

The loop never breaks because the test inflater.finished() is never true even if inputLen
is 0. Thus the service hangs indefinitely.

I am classifying this as Critical because, essentially, by crafting a certain type of request,
I can execute a denial of service attack against the service.

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