Sunday, 24 June 2012

O2 .NET SAST Engine: MethodStream and CodeStrams for a WebService Method

One of the hidden Gems of the O2 Platform is its SAST engine that is able to create what its called MethodSteams and CodeSteams (from C# code).

MethodSteams are a code representation of an entire call-tree, i.e. one file that contains the original method and all the methods it calls (recursively).

CodeSteams are all the possible 'taint follow' paths that exist on a particular MethodSteam

Here are they in action in the HacmeBank's source code:

Part 1 : The MethodStream

A MethodStream is a file which contains all methods that are called from a particular source method.

For example the HacmeBank's WebService method:



who calls the DataFactory method:



who calls the SqlEngine method:



So, in this case the MethodStream for the CreateUser WebService method looks like this:



and



(the above auto generated methods are methods that the engine was able to resolve but the source code was not available)


Part 2: The CodeStream

The CodeStream is a unique data-flow path created from a starting point inside a provided MethodStream, for example here is an SQL Injection:







Part 3: Following Taint Step by Step

step 1:


step 2:


step 3:


step 4:


step 5:


step 6:


step 7:


step 8:


step 9:




Part 4: Graph with trace

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