iOS Kernel Heap Armageddon - Hakim

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Heap Feng Shui / Heap Massage / ... • allocate repeatedly ✔ • allocate arbitrary sized memory blocks ✔ • poke allocation holes in specific positions • control the memory layout • fill memory with interesting meta / application data ✔ Stefan Esser • iOS Kernel Heap Armageddon REVISITED • July 2012 • 94
Poking Holes into Allocated Data • deallocation of arbitrary sized memory is possible with • reusing the same dictionary key will delete the previously inserted value • in this example the middle value ZZZ...ZZZ is freed AAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA BBBB AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA CCCC ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ DDDD AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA EEEE AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA CCCC Stefan Esser • iOS Kernel Heap Armageddon REVISITED • July 2012 • 95
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http://www.sektioneins.de iOS Kerne
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DISCLAIMER iOS 6 • is in beta =>
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So what is this talk about? • zon
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Some Kernel Zones $ zprint kalloc e
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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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Exploiting the freelist in iOS 6
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Overview Managers and Wrappers not
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kalloc() • kalloc() is a wrapper
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kfree() • kfree() is a bit specia
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_MALLOC() • _MALLOC() is a wrappe
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_MALLOC() in iOS 5.x void *_MALLOC(
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What about kern_os_malloc(), new an
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mcache / slab could and might fill
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kernel_memory_allocate • “maste
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Cross Zone Attacks • what is the
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Visualization of Zone Page Allocati
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Page 43 and 44: Visualization of Zone Page Allocati
Page 61 and 62: Zone Page Allocation Distribution (
Page 63 and 64: Cross Memory Allocator Attacks •
Page 65 and 66: iOS Kernel C++ • iOS kernel‘s l
Page 67 and 68: OSObject Memory Layout 0x00 0x04 vt
Page 69 and 70: Overwriting an OSObject in Memory
Page 71 and 72: OSArray Memory Layout and Overwriti
Page 73 and 74: “Generic“ Technique to control
Page 75 and 76: Heap Feng Shui / Heap Massage / ...
Page 77 and 78: OSUnserializeXML() • deserializat
Page 79 and 80: How does the parser work? (II) •
Page 81 and 82: How does the parser work? (IV) •
Page 83 and 84: How does the parser work? (VI) •
Page 85 and 86: How does the parser work? (VIII)
Page 87 and 88: Heap Spraying (Remember?) • alloc
Page 89 and 90: Heap Spraying • allocate repeated
Page 91 and 92: Heap Spraying • allocate repeated
Page 93: Fill Arbitrary Sized Memory Blocks
Page 97 and 98: Extra: Keeping Data Allocated • s
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iOS Kernel Heap Armageddon - Hakim

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