iOS Kernel Heap Armageddon - Hakim
iOS Kernel Heap Armageddon - Hakim iOS Kernel Heap Armageddon - Hakim
iOS Kernel Zone Allocator 101 • in case of a buffer overflow the freelist pointer is overwritten • next allocation will make attacker controlled pointer the head of freelist • and the allocation following after will return the injected pointer adjacent memory blocks head of freelist allocated block overflowing into free one attacker data head of freelist Stefan Esser • iOS Kernel Heap Armageddon REVISITED • July 2012 • 14
Exploiting the freelist in iOS 6 • Apple has changed the freelist handling in iOS 6 • memory is now tagged with a fixed value • doesn‘t stop freelist exploitation • but stops exploitation method used in all public iOS heap exploits Stefan Esser • iOS Kernel Heap Armageddon REVISITED • July 2012 • 15
- Page 1 and 2: http://www.sektioneins.de iOS Kerne
- Page 3 and 4: DISCLAIMER iOS 6 • is in beta =>
- Page 5 and 6: So what is this talk about? • zon
- Page 7 and 8: Some Kernel Zones $ zprint kalloc e
- Page 9 and 10: iOS Kernel Zone Allocator 101 • k
- Page 11 and 12: iOS Kernel Zone Allocator 101 • z
- Page 13: iOS Kernel Zone Allocator 101 • w
- 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
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- Page 61 and 62: Zone Page Allocation Distribution (
- Page 63 and 64: Cross Memory Allocator Attacks •
<strong>iOS</strong> <strong>Kernel</strong> Zone Allocator 101<br />
• in case of a buffer overflow the freelist pointer is overwritten<br />
• next allocation will make attacker controlled pointer the head of freelist<br />
• and the allocation following after will return the injected pointer<br />
adjacent memory blocks<br />
head of freelist<br />
allocated block overflowing into free one<br />
attacker<br />
data<br />
head of freelist<br />
Stefan Esser • <strong>iOS</strong> <strong>Kernel</strong> <strong>Heap</strong> <strong>Armageddon</strong> REVISITED • July 2012 •<br />
14
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