Adding ASLR to Jailbroken iPhones [PDF] - Antid0te

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Random Thoughts • Random Thoughts • ARM is a very nice arch because of alignment • ObjC binaries come with a lot of known structs in the binaries • iOS 4.2.1 main binaries don‘t require TEXT relocation • some sections do not require relocation • some sections are just pointer lists (=> relocation easy) • some sections are „more difficult“ Stefan Esser • Adding ASLR to jailbroken iPhones • December 2010 • 50
Crazy Solution • Crazy Solution • the only problem are sections which are „more difficult“ • some of these sections contain known ObjC structs (we can parse those and fixup all pointers) • and some don‘t • what about a brute force pointer detection approach? Stefan Esser • Adding ASLR to jailbroken iPhones • December 2010 • 51
Page 1 and 2: http://www.sektioneins.de Adding AS
Page 3 and 4: What the talk is NOT about This tal
Page 5 and 6: Part I Introduction Stefan Esser
Page 7 and 8: Jailbroken iPhones and Security •
Page 9 and 10: Codesigning ??? • every binary on
Page 11 and 12: Example Crashdump CrashReporter Key
Page 13 and 14: Part II Dyld Shared Cache and ASLR
Page 15 and 16: Libraries where are thou? • since
Page 17 and 18: dyld_shared_cache Header Stefan Ess
Page 19 and 20: Rebasing the Libraries... • okay
Page 21 and 22: the iPhone SDK to the rescue? (II)
Page 23 and 24: Okay what now ? looking at differen
Page 25 and 26: Obvious Complications • different
Page 27 and 28: Let‘s start diffing • Python im
Page 29 and 30: Analysing the results (I) • Expec
Page 31 and 32: What are the two large unknown valu
Page 33 and 34: Small Values and Pointers • some
Page 35 and 36: iPhone libobjc does not match the s
Page 37 and 38: Analysing the different pointer pro
Page 39 and 40: What needs to be rebased? • image
Page 41 and 42: The Dynamic Linker • iPhone OS /
Page 43 and 44: Relocating the Dynamic Linker (II)
Page 45 and 46: Stack Randomization (I) • stack o
Page 47 and 48: Stack Randomization Test int main()
Page 49: Baby Steps... • generic solution
Page 53 and 54: Brute Force Pointer Detection (II)
Page 55 and 56: Part IV Installing it on the iPhone
Page 57 and 58: Analysis of current Jailbreak • /
Page 59 and 60: Installing an alternative dyld •
Page 61 and 62: Thank you for listening... DEMO Ste

Adding ASLR to Jailbroken iPhones [PDF] - Antid0te

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