CWE-825: Expired Pointer Dereference
The product dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid.
How it's found
Expired Pointer Dereference 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.
When a product releases memory, but it maintains a pointer to that memory, then the memory might be re-allocated at a later time. If the original pointer is accessed to read or write data, then this could cause the product to read or modify data that is in use by a different function or process. Depending on how the newly-allocated memory is used, this could lead to a denial of service, information exposure, or code execution.
Consequences
- Read Memory: If the expired pointer is used in a read operation, an attacker might be able to control data read in by the application.
- DoS: Crash, Exit, or Restart: If the expired pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
- Execute Unauthorized Code or Commands: If the expired pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
Mitigations
- Architecture and Design: Choose a language that provides automatic memory management.
- Implementation: When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
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-825?
The product dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid.
How do you find Expired Pointer Dereference?
Expired Pointer Dereference 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-825?
Read Memory: If the expired pointer is used in a read operation, an attacker might be able to control data read in by the application. DoS: Crash, Exit, or Restart: If the expired pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur. Execute Unauthorized Code or Commands: If the expired pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
Does TurboPentest test for Expired Pointer Dereference?
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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