iOS Kernel Heap Armageddon

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Heap Spraying • allocate repeatedly ✔ • allocate attacker controlled data • allocate large quantities of data in a row ✔ • usually fill memory with specific pattern Stefan Esser • iOS Kernel Heap Armageddon • April 2012 • 86
Allocate Attacker Controlled Data • by putting data into a tag we can fill memory with any data • because data is either in base64 or hex format we can have NULs • is more convenient than because it reads in chunks of 4096 ThisIsOurData VGhpcyBJcyBPdXIgRGF0YSB3aXRoIGEgTlVMPgA8+ADw= 00112233445566778899aabbccddeeff ... Stefan Esser • iOS Kernel Heap Armageddon • April 2012 • 87
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iOS Kernel Heap Armageddon Stefan E
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Recap... • public iOS kernel heap
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Part I Zone Allocator Recap Stefan
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iOS Kernel Zone Allocator 101 • k
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iOS Kernel Zone Allocator 101 • z
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iOS Kernel Zone Allocator 101 • w
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Part II Other Heap Managers and Wra
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Let‘s have a look at kalloc() Ste
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iOS 5 - kalloc() Zones $ zprint kal
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Let‘s have a look at _MALLOC() St
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_MALLOC() in iOS 4.x void *_MALLOC(
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Overwriting _MALLOC()ed Data • ch
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kern_os_malloc() • kern_os_malloc
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and kernel_memory_allocate ??? Stef
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Part III Cross Zone or Cross Memory
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Visualization of Zone Page Allocati
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Visualization of Zone Page Allocati
Page 35 and 36: Visualization of Zone Page Allocati
Page 57 and 58: Zone Page Allocation Distribution
Page 59 and 60: Zone Page Allocation Distribution
Page 61 and 62: Part IV Kernel Heap Application Dat
Page 63 and 64: iOS Kernel C++ Base Objects Stefan
Page 65 and 66: OSObject Retain Count • reference
Page 67 and 68: OSString Memory Layout and Overwrit
Page 69 and 70: Part V “Generic“ Technique to c
Page 71 and 72: Heap Spraying • allocate repeated
Page 73 and 74: Once Technique to rule them all...
Page 75 and 76: How does the parser work? (I) • p
Page 77 and 78: How does the parser work? (III) •
Page 79 and 80: How does the parser work? (V) • k
Page 81 and 82: How does the parser work? (VII) •
Page 83 and 84: Memory Sizes Cheat Sheet OSArray OS
Page 85: Allocate Repeatedly • there is no
Page 89 and 90: Heap Feng Shui / Heap Massage / ...
Page 95: Questions ? Stefan Esser • iOS Ke
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iOS Kernel Heap Armageddon

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