CREATING STACK POSITION DEPENDENT CRYPTOGRAPHIC RETURN ADDRESS TO MITIGATE RETURN ORIENTED PROGRAMMING ATTACKS

• US 20160094552A1
• Filed: 09/26/2014
• Published: 03/31/2016
• Est. Priority Date: 09/26/2014
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Durham, David M., Patel, Baiju V.
• Granted Patent: US 9,514,285 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 21/00 Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
• CPC Class Codes: G06F 21/52 during program execution, e.g. stack integrity ; Preventing unwanted data erasure; Buffer overflow

Abstract

A computing device includes technologies for securing return addresses that are used by a processor to control the flow of execution of a program. The computing device uses a cryptographic algorithm to provide security for a return address in a manner that binds the return address to a location in a stack.

Claims

1. A computing device to secure return addresses to mitigate return oriented programming attacks, the computing device comprising:

a processor comprising call logic,

wherein, prior to storage of a return address on a call stack, the call logic is to;

read a secret key from a memory location of the computing device that is readable by the processor;

determine a stack position identifier, the stack position identifier usable to determine a location on the call stack at which the return address is to be stored;

generate security data by execution of a cryptographic algorithm with a plurality of inputs including;

(i) the secret key and (ii) the stack position identifier, the output of the cryptographic algorithm being the security data; and

store the security data in a memory location that is readable by the processor.

2. The computing device of claim 1, wherein the cryptographic algorithm comprises an encryption algorithm, the plurality of inputs to the cryptographic algorithm further includes (iii) at least a portion of the return address, and the call logic is to execute the cryptographic algorithm with the stack position identifier as a tweak, such that the security data is a modified return address, and the call logic is to store the modified return address on the call stack.

3. The computing device of claim 2, wherein the encryption algorithm comprises a tweakable block cipher.

4. The computing device of claim 2, wherein the call logic is to further modify the modified return address by manipulation of at least a portion of the modified return address such that the further-modified return address falls within an unused range of memory addresses and store the further-modified return address on the call stack.

5. The computing device of claim 2, wherein the processor comprises return logic and wherein, prior to return of program execution control to a return address on the call stack, the return logic is to:

obtain the modified return address from the call stack;

decrypt the encrypted portion of the return address by execution of a decryption algorithm with the stack position identifier as the tweak; and

transfer program execution control to the address of the decrypted return address.

6. The computing device of claim 5, wherein the call logic is to further modify the modified return address by manipulation of the modified return address to fall within an unused range of memory addresses and store the further-modified return address on the call stack, and the return logic is to obtain the further-modified return address from the call stack, and manipulate the further-modified return address to restore the modified return address to its original format.

7. The computing device of claim 2, wherein the processor comprises return address descrambling logic to:

determine if the modified return address has been modified to fall within an unused range of memory addresses; and

if the modified return address has been modified to fall within an unused range of memory addresses, decrypt the encrypted portion of the return address by execution of a decryption algorithm with the stack position identifier as the tweak.

8. The computing device of claim 1 or claim 2, wherein the call logic is to:

compute the security data by execution of a message authentication code algorithm, such that the security data comprises a message authentication code; and

store the security data in address bits that are within an unused range of memory addresses.

9. The computing device of claim 8, wherein the processor comprises return logic and wherein, prior to return of program execution control to a return address on the call stack, the return logic is to:

obtain the message authentication code from the unusable memory location;

obtain a current return address from the top of the call stack;

compute second security data by execution of the message authentication code algorithm with (i) the secret key and (ii) the stack position identifier, as inputs;

compare the second security data to the security data; and

if the second security data and the security data match, transfer program execution control to the address of the current return address.

10. The computing device of claim 1 or claim 2, wherein the stack position identifier comprises one of:

a stack pointer indicative of the top of the stack, an instruction pointer indicative of a memory address of a currently executing instruction, a page identifier representative of a range of memory addresses including the address, and a tracking counter indicative of one or more of;

a number of calls executed by the call logic and a number of returns executed by the return logic.

11. The computing device of claim 1 or claim 2, wherein the call logic is to encrypt at least a portion of the stack position identifier by execution of an encryption algorithm with the security key.

12. The computing device of claim 11, wherein the call logic is to modify the return address by combination of at least a portion of the return address with the encrypted stack position identifier.

13. The computing device of claim 12, wherein the call logic is to combine the return address with the encrypted stack position identifier by execution of an exclusive-or (XOR) operation, a reduced round cipher, or a full round cipher.

14. The computing device of claim 13, wherein the call logic is to:

compute a predicted stack position identifier representative of a range of memory addresses ahead or behind the range of memory addresses of the stack position identifier, and encrypt the predicted stack position identifier in parallel with the combination of the return address with the encrypted stack position identifier.

15. A method for securing an address used by a processor of a computing device to control the flow of execution of a program, the method comprising:

prior to storing an address on a stack;

reading a secret key from a memory location of the computing device that is readable by the processor;

determining a stack position identifier, the stack position identifier usable to determine a location on the stack at which the address is to be stored;

generating security data by executing a cryptographic algorithm with a plurality of inputs including;

(i) the secret key and (ii) the stack position identifier, the output of the cryptographic algorithm being the security data; and

storing the security data in a memory location that is readable by the processor.

16. The method of claim 15, wherein the cryptographic algorithm comprises an encryption algorithm, the plurality of inputs to the cryptographic algorithm further includes (iii) at least a portion of the address, and the method comprises executing the cryptographic algorithm using the stack position identifier as a tweak, such that the security data is a modified address, and storing the modified address on the stack.

17. The method of claim 15, comprising further modifying the modified address by manipulating at least a portion of the modified address such that the further-modified address falls within an unused range of memory addresses, and storing the further-modified address on the stack.

18. The method of claim 15, comprising, prior to directing program execution control to an address on the stack:

obtaining the modified address from the stack;

decrypting the encrypted portion of the address by executing a decryption algorithm using the stack position identifier as the tweak;

transferring program execution control to the address of the decrypted address;

further modifying the modified address by manipulating the modified address to fall within an unused range of memory addresses;

storing the further-modified address on the stack;

obtaining the further-modified address from the stack; and

manipulating the further-modified address to restore the modified address to its original format.

19. One or more non-transitory machine readable storage media comprising a plurality of instructions stored thereon that in response to being executed result in a computing device securing an address used by a processor of a computing device to control the flow of execution of a program, by:

prior to storing an address on a stack;

reading a secret key from a memory location of the computing device that is readable by the processor;

determining a stack position identifier, the stack position identifier usable to determine a location on the stack at which the address is to be stored;

generating security data by executing a cryptographic algorithm with a plurality of inputs including;

(i) the secret key and (ii) the stack position identifier, the output of the cryptographic algorithm being the security data; and

storing the security data in a memory location that is readable by the processor.

20. The one or more non-transitory machine readable storage media of claim 19, wherein the cryptographic algorithm comprises an encryption algorithm, the plurality of inputs to the cryptographic algorithm further includes (iii) at least a portion of the address, and the instructions result in the computing device executing the cryptographic algorithm using the stack position identifier as a tweak, such that the security data is a modified address, and storing the modified address on the stack.

21. The one or more non-transitory machine readable storage media of claim 19, wherein the instructions result in the computing device further modifying the modified address by manipulating at least a portion of the modified address such that the further-modified address falls within an unused range of memory addresses, and storing the further-modified address on the stack.

22. The one or more non-transitory machine readable storage media of claim 19, wherein the instructions result in the computing device, prior to directing program execution control to an address on the stack:

obtaining the modified address from the stack;

decrypting the encrypted portion of the address by executing a decryption algorithm using the stack position identifier as the tweak;

transferring program execution control to the address of the decrypted address;

further modifying the modified address by manipulating the modified address to fall within an unused range of memory addresses;

storing the further-modified address on the stack;

obtaining the further-modified address from the stack; and

manipulating the further-modified address to restore the modified address to its original format.

23. The one or more non-transitory machine readable storage media of claim 22, wherein the instructions result in the computing device:

determining if the modified address has been modified to fall within an unused range of memory addresses; and

if the modified address has been modified to fall within an unused range of memory addresses, decrypting the encrypted portion of the address by executing a decryption algorithm using the stack position identifier as the tweak.

24. The one or more non-transitory machine readable storage media of claim 19, wherein the instructions result in the computing device:

computing the security data by executing a message authentication code algorithm, such that the security data comprises a message authentication code; and

storing the security data in a memory location that is within an unused range of memory addresses.

25. The one or more non-transitory machine readable storage media of claim 19, wherein the instructions result in the computing device computing a predicted stack position identifier representing a range of memory addresses ahead or behind a range of memory addresses of the stack position identifier, and encrypting the predicted stack position identifier in parallel with the combining of the address with the encrypted stack position identifier.