Re^6: On showing the weakness in the MD5 digest function and getting bitten by scalar contextby BrowserUk (Pope)
|on Aug 27, 2004 at 22:06 UTC||Need Help??|
Maybe I am? Did you find something somewhere that suggested that they could start with an md5 and generate a plaintext with that md5?
What I read, led me to believe that what they were saying is that they had discovered a way to take one piece of plain text, generate its md5, and then by manipulating the original plaintext, generate another plaintext with the same md5.
But note. If I read it right, they need the original text to produce the new one.
For password applications, this means they would need the original password in order to produce another piece of text that had the same md5. But why bother when you have the original password?
So what other vulnerabilities arise from this discovery? If they start with the source or binary of some application that is downloadable and is checksummed with md5. They produce a modified version of that binary with the same md5. Will it run? Will it open a known port and listen for mother? Will it monitor the keyboard for passwords?
Or, they have the text of an important message and it's md5. They produce a different message with the same md5. Will it cause the bank to transfer funds to their bank account? Or recall the nuclear bombers? Instruct the enemies operative in Washington to fall into the counter espionage trap at the cafe? Will it even be readable as English (French, German, Chinese or Swahili)?
If the md5 is being used to stop them from knowing the text it was generated from (password), and they need to know that password to exploit the md5--no vulnerability.
If there is open access to the plaintext, and the md5 is designed to ensure that the plaintext hasn't been altered, they can produce another plaintext with the same md5, but will it make any sense? Never mind actually do anything subversive, or to their advantage.
Maybe I misunderstood what I read? Maybe, there is an application that allows the fact the the alternative plaintext is gibberish to be ignored and compromise something?