iOS Kernel Heap Armageddon - Hakim

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Zone Page Allocation Distribution • accross 25 reboots there was a single common page among all the allocations • the 26th reboot made it go away • because of the randomness adjacent memory pages are very unlikely • it is not possible to say anything about the relative position of pages • overflowing out of a page will most likely crash • ... but this is only true for single page zone Stefan Esser • iOS Kernel Heap Armageddon REVISITED • July 2012 • 62
Cross Memory Allocator Attacks • most of the allocation functions deeply down use the zone allocator • if allocation functions share the same zone then cross attacks are possible • everything based on kalloc() is affected • e.g. new , kern_os_malloc, _MALLOC, kalloc Stefan Esser • iOS Kernel Heap Armageddon REVISITED • July 2012 • 63
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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
Page 11 and 12: iOS Kernel Zone Allocator 101 • z
Page 13 and 14: iOS Kernel Zone Allocator 101 • w
Page 15 and 16: Exploiting the freelist in iOS 6
Page 17 and 18: Overview Managers and Wrappers not
Page 19 and 20: kalloc() • kalloc() is a wrapper
Page 21 and 22: kfree() • kfree() is a bit specia
Page 23 and 24: _MALLOC() • _MALLOC() is a wrappe
Page 25 and 26: _MALLOC() in iOS 5.x void *_MALLOC(
Page 27 and 28: What about kern_os_malloc(), new an
Page 29 and 30: mcache / slab could and might fill
Page 31 and 32: kernel_memory_allocate • “maste
Page 33 and 34: Cross Zone Attacks • what is the
Page 35 and 36: Visualization of Zone Page Allocati
Page 61: Zone Page Allocation Distribution (
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 and 94: Fill Arbitrary Sized Memory Blocks
Page 95 and 96: Poking Holes into Allocated Data
Page 97 and 98: Extra: Keeping Data Allocated • s
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iOS Kernel Heap Armageddon - Hakim

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