Not So Random

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PHP Bounded mt_rand() – Patched Untwister … uint32_t PHP_mt19937::random( { uint32_t result = genrand_int32(m_mt) >> 1; if (m_isBounded) { result = (uint32_t)((m_minBound) + (long) ((double) ( (double) (m_maxBound) - (m_minBound) + 1.0) * ((result) / ((2147483647) + 1.0)))); } return result; } … void PHP_mt19937::setBounds(uint32_t min, uint32_t max) { m_minBound = min; m_maxBound = max; m_isBounded = true; } … Not So Random
PHP Bounded mt_rand() – Patched Untwister … uint32_t PHP_mt19937::random( { uint32_t result = genrand_int32(m_mt) >> 1; if (m_isBounded) { result = (uint32_t)((m_minBound) + (long) ((double) ( (double) (m_maxBound) - (m_minBound) + 1.0) * ((result) / ((2147483647) + 1.0)))); } return result; } … void PHP_mt19937::setBounds(uint32_t min, uint32_t max) { m_minBound = min; m_maxBound = max; m_isBounded = true; } … Not So Random
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Not So Random Exploiting Unsafe Ran
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Talk Overview 1. Theory: • Why?
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Why do we need random numbers? •
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Random numbers in Web Applications
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Concept of Randomness • define: r
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PRNG PRNG r = random.Random() Not S
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PRNG 16768642083820545282 323536147
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PRNG PRNG 16768642083820545282 3235
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PRNG Seeds, States and Periods 1. S
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PRNG Seeds and States Seed (/dev/ur
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CSPRNG vs PRNG 1. Non-Deterministic
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Language Examples Language Method P
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Internals Glance public Random(int
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Exploitation Theory • Want to obt
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Exploitation Theory Target PRNG Out
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Exploitation Theory Target PRNG Out
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Exploitation Theory Target PRNG Obt
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Exploitation Theory Our PRNG Obtain
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Untwister Brute Force Algorithm 101
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Page 63 and 64: Untwister Brute Force Algorithm 101
Page 65 and 66: Demos 1. Brute Force • PHP mt_ran
Page 67 and 68: Overview - Brute Force 1. Generate
Page 73 and 74: Brute Force - Source class ResetPas
Page 75 and 76: PHP mt_rand()- Exploitation • Rec
Page 77 and 78: PHP mt_rand()- Exploitation • Tar
Page 79 and 80: PHP mt_rand()- Exploitation Theory
Page 81 and 82: PHP mt_rand() - Untwister uint32_t
Page 83 and 84: PHP mt_rand()- Exploitation root@ka
Page 85 and 86: PHP mt_rand()- Exploitation class R
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Page 91 and 92: PHP mt_rand()- Exploitation “To r
Page 93 and 94: Demos 1. Brute Force • PHP mt_ran
Page 95 and 96: Overview - Brute Force Bounded Call
Page 101 and 102: Brute Force Bounded Call - Source c
Page 103 and 104: PHP mt_rand(0,61)- Exploitation •
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Page 107 and 108: Exploitation Theory Target PRNG Obt
Page 109 and 110: PHP mt_rand(0,61)- Decoder #!/usr/b
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Page 113: PHP Bounded mt_rand() Constructor
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Page 119 and 120: 4. Seed new PRNG with obtained seed
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Page 125 and 126: PHP mt_rand(0,61)- Exploitation Not
Page 127 and 128: Exploitation Theory Our PRNG Obtain
Page 129 and 130: Overview - Weak Seeds 1. Generate a
Page 135 and 136: Weak Seeds - Source public class Re
Page 137 and 138: .NET System.Random() Constructor
Page 139 and 140: .NET System.Random()- Exploitation
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Page 145 and 146: System.Random() Constructor • .NE
Page 147 and 148: System.Random() Untwister Patch int
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Page 163 and 164: Practical Exploitation - Tips • L
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Mitigations Need a truly random num
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Developers, Developers, Developers
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Links / Further Reading • https:/
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Not So Random

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