Sources of (pseudo)randomness in ASLR

Discussion in 'other security issues & news' started by Gullible Jones, Feb 15, 2013.

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  1. Just a couple of ASLR related questions:

    1. What sorts of (pseudo)random number generators are usually used for ASLR?

    2. Could some of the ones used in cryptography - e.g. Blowfish's key generator - be of use for randomizing memory allocations?

    (Also, am I making sense?)
     
  2. Hungry Man

    Hungry Man Registered Member

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    It's just a few bits of entropy - it works by allocating memory to the location that the program would normally allocate, and to avoid a collision it then allocates to a new area.

    Not sure what's behind it, or how the address is generated, but it's handled natively by windows.

    Realizing that you're talking about ASLR and not PseudoASLR.

    I can't speak for Windows, but on Linux I believe entropy is gathered from various sources. It depends on whether it uses random or urandom. But things like mouse movements and key presses will increase entropy.
     
  3. Ah, I was thinking it would use pseudorandom numbers. My thought was that maybe a higher quality pseudorandom number generator could make it more powerful.
     
  4. Hungry Man

    Hungry Man Registered Member

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    It does. But the generator needs to be seeded by different sources. A better generator would lead to better ASLR.
     
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