Dedup Est Machina

Memory Deduplicationas an Advanced Exploitation Vector

Erik Bosman, Kaveh Razavi, Herbert Bos and Cristiano Giuffrida

Deduplication(software side-channel)

+Rowhammer

(hardware bug)

1

Deduplication(software side-channel)

+Rowhammer

(hardware bug)

Exploit MS Edge without software bugs(from JavaScript)

1

Deduplication

- leak heap & code pointer addresses

2

Deduplication

- leak heap & code pointer addresses

+3.141592

+0.0

42.

1

NaN

JavaScript Array

2

Deduplication

- leak heap & code pointer addresses

+3.141592

+0.0

42.

1

NaN

JavaScript Array chakra.dll

2

Deduplication

- leak heap & code pointer addresses- create a fake object

3

Deduplication

Rowhammer

- leak heap & code pointer addresses- create a fake object

- create reference to our fake object

3

Deduplication

Rowhammer

- leak heap & code pointer addresses- create a fake object

- create reference to our fake object

3

deduplication side-channel attack

physical memory attacker process

victim process

4

deduplication side-channel attack

physical memory attacker process

victim process

4

deduplication side-channel attack

physical memory attacker process

victim process

4

deduplication side-channel attack

physical memory attacker process

victim process

4

deduplication side-channel attack

physical memory attacker process

victim process

** * * *

* ***

* * * * * * ** *

* * * * * * ***

4

deduplication side-channel attack

normal write

5

deduplication side-channel attack

normal write

write

5

deduplication side-channel attack

normal write

copy on write (due to deduplication)

write

*5

deduplication side-channel attack

normal write

copy on write (due to deduplication)

write

copypage contents write

*5

Can we generalize this to leaking arbitrary data, like an ASLR pointer or a password?

6

Challenge 1:

The secret we want to leak does not span an entire page.

7

turning a secret into a page

secret

8

turning a secret into a page

known data

secret

secret page8

Challenge 2:

The secret we want to leak has too much entropy to leak all at once.

9

primitive #1: alignment probing

known data

secret

secret page10

primitive #1: alignment probing

known data

secret

secret page10

primitive #2: partial reuse

known data

secret

secret page11

primitive #2: partial reuse

known data

secret

secret page11

JIT function epilogue (MS Edge)

mov RCX,0x1c20 mov RAX, [code address] jmp RAX trap

trap trap trap trap trap trap ...trap trap trap trap trap trap

trap trap

12

JIT function epilogue (MS Edge)

mov RCX,0x1c20 mov RAX, [code address] jmp RAX trap

trap trap trap trap trap trap

trap

trap trap trap trap trap trap

trap trap trap trap trap trap

trap trap trap trap trap

trap trap

12

JIT function epilogue (MS Edge)

mov RCX,0x1c20 mov RAX, [code address] jmp RAX trap

trap trap trap trap trap trap

trap

trap trap trap trap trap trap

trap trap trap trap trap trap

trap trap trap trap trap

trap

12

JIT function epilogue (MS Edge)

mov RCX,0x1c20 mov RAX, [code address] jmp RAX trap

trap trap trap trap trap trap

trap

trap trap trap trap trap trap

trap trap trap trap trap trap

trap trap trap trap trap

12

But what if we can't leak part of the secret?

13

birthday problem

14

birthday problem

14

birthday problem

14

birthday problem

14

birthday problem

14

birthday problem

14

birthday problem

14

birthday problem

14

birthday problem

14

birthday problem

14

birthday problem

14

birthday problem

14

birthday problem

14

primitive #3: birthday heapspray

physical memory attacker memory

victim memory

15

primitive #3: birthday heapspray

physical memory attacker memory

victim memory

15

primitive #3: birthday heapspray

physical memory attacker memory

victim memory

15

primitive #3: birthday heapspray

physical memory attacker memory

victim memory

15

primitive #3: birthday heapspray

physical memory attacker memory

victim memory

15

primitive #3: birthday heapspray

physical memory attacker memory

victim memory

15

primitive #3: birthday heapspray

physical memory attacker memory

victim memory

15

primitive #3: birthday heapspray

physical memory attacker memory

victim memory

15

primitive #3: birthday heapspray

physical memory attacker memory

victim memory

15

primitive #3: birthday heapspray

physical memory attacker memory

victim memory

15

primitive #3: birthday heapspray

physical memory attacker memory

*victim memory

*

15

pointer pivotting

arraydata

16

pointer pivotting

arraydata

arrayheader

JavaScript Array

16

pointer pivotting

arraydata

arrayheader

arrayheader

arraydata

JavaScript Array JavaScript Array

16

pointer pivotting

arraydata

arrayheader

arrayheader

arraydata

JavaScript Array JavaScript Array

16

pointer pivotting

arraydata

arrayheader

arrayheader

arraydata

JavaScript Array JavaScript Array

16

rowhammer attack

DDR memory

rows

17

rowhammer attack

DDR memory

rowactivation

17

rowhammer attack

DDR memory

rowactivation

17

rowhammer attack

DDR memory

rowactivation

17

pointer pivotting

arraydata

arrayheader

arrayheader

arraydata

JavaScript Array JavaScript Array

18

pointer pivotting

arraydata

arrayheader

arrayheader

arraydata

JavaScript Array JavaScript Array

18

in short:

- Memory deduplication is a more powerfulside-channel than previously thought.

- Reliable browser exploitation usingrowhammer in JavaScript is possible.

(on Windows 10, MS Edge, without using any bugs)

> Disable-MMAgent -PageCombining

19