CWE-1252: CPU Hardware Not Configured to Support Exclusivity of Write and Execute Operations
The CPU is not configured to provide hardware support for exclusivity of write and execute operations on memory. This allows an attacker to execute data from all of memory.
How it's found
CPU Hardware Not Configured to Support Exclusivity of Write and Execute Operations is typically found by tracing untrusted input from where it enters the system to the point where it is used without the check or neutralization this weakness describes, combining manual code review with dynamic testing.
CPUs provide a special bit that supports exclusivity of write and execute operations. This bit is used to segregate areas of memory to either mark them as code (instructions, which can be executed) or data (which should not be executed). In this way, if a user can write to a region of memory, the user cannot execute from that region and vice versa. This exclusivity provided by special hardware bit is leveraged by the operating system to protect executable space. While this bit is available in most modern processors by default, in some CPUs the exclusivity is implemented via a memory-protection unit (MPU) and memory-management unit (MMU) in which memory regions can be carved out with exact read, write, and execute permissions. However, if the CPU does not have an MMU/MPU, then there is no write exclusivity.
Consequences
- Execute Unauthorized Code or Commands: Without configuring exclusivity of operations via segregated areas of memory, an attacker may be able to inject malicious code onto memory and later execute it.
Mitigations
- Architecture and Design: Implement a dedicated bit that can be leveraged by the Operating System to mark data areas as non-executable. If such a bit is not available in the CPU, implement MMU/MPU (memory management unit / memory protection unit).
- Integration: If MMU/MPU are not available, then the firewalls need to be implemented in the SoC interconnect to mimic the write-exclusivity operation.
Where this fits in a TurboPentest engagement
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Frequently asked questions
What is CWE-1252?
The CPU is not configured to provide hardware support for exclusivity of write and execute operations on memory. This allows an attacker to execute data from all of memory.
How do you find CPU Hardware Not Configured to Support Exclusivity of Write and Execute Operations?
CPU Hardware Not Configured to Support Exclusivity of Write and Execute Operations is typically found by tracing untrusted input from where it enters the system to the point where it is used without the check or neutralization this weakness describes, combining manual code review with dynamic testing.
What is the impact of CWE-1252?
Execute Unauthorized Code or Commands: Without configuring exclusivity of operations via segregated areas of memory, an attacker may be able to inject malicious code onto memory and later execute it.
Does TurboPentest test for CPU Hardware Not Configured to Support Exclusivity of Write and Execute Operations?
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
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Written and reviewed by
Michel Chamberland - Founder & CEO, IntegSec
CISSP, OSCP, OSCE, CEH, GIAC, CCSK · 20+ years in offensive security
Michel has spent 20+ years on offensive security teams including IBM X-Force Red and Trustwave SpiderLabs, leading penetration tests, red team engagements, and breach response for Fortune 500 customers. He is the founder of IntegSec and the architect of TurboPentest.
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