Adding ASLR to Jailbroken iPhones [PDF] - Antid0te

Recommendations

Info

Segment Splitting ? • linker groups __TEXT and __DATA sections • one block of read / execute sections • one block of read / write sections • (base of __DATA - base of __TEXT) fixed in SDK libraries ➡ however in dyld_shared_cache case we need to change delta Stefan Esser • Adding ASLR to jailbroken iPhones • December 2010 • 22
Okay what now ? looking at different shared caches revealed the following ➡ they seem to be made on the same machine ➡ the same binaries are used during construction ➡ library base addresses differ due to random load order /usr/lib/libSystem.B.dylib iPhone 4 iPod 4 iPad inode 0x0933DE37 0x0933DE37 0x0933DE37 mtime 0x4CC1050A 0x4CC1050A 0x4CC1050A base 0x33B5C000 0x31092000 0x30D03000 /usr/lib/libobjc.dylib iPhone 4 iPod 4 iPad inode 0x093AF2FC 0x093AF2FC 0x093AF2FC mtime 0x4CC10998 0x4CC10998 0x4CC10998 base 0x33476000 0x33A03000 0x34A7D000 Stefan Esser • Adding ASLR to jailbroken iPhones • December 2010 • 23
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: the iPhone SDK to the rescue? (II)
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 and 50: Baby Steps... • generic solution
Page 51 and 52: Crazy Solution • Crazy 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

Create successful ePaper yourself

Delete template?

Save as template?