CWE-825: Expired Pointer Dereference
Official CWE-825 CWE context with Glexia analysis, remediation guidance, related CVEs, and ATT&CK context.
Glexia's Take
CWE-825: Dangling pointer
Expired Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Confidentiality: 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.
- Availability: 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.
- Integrity,Confidentiality,Availability: 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.
Developer Pattern
CWE-825 is the kind of defect developers can usually prevent with explicit validation, safer framework defaults, and tests that exercise hostile input or unsafe state transitions.
Confidence
high confidence from CWE-825, 4.20.
Official CWE Definition
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The product dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid.
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.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- The following code shows a simple example of a use after free error: When an error occurs, the pointer is immediately freed. However, this pointer is later incorrectly used in the logError function.
- The following code shows a simple example of a double free error: Double free vulnerabilities have two common (and sometimes overlapping) causes:,[object Object],Although some double free vulnerabilities are not much more complicated than the previous example, most are spread out across hundreds of lines of code or even different files. Programmers seem particularly susceptible to freeing global variables more than once.
Remediation
- 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.
Detection
- Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
- Automated Dynamic Analysis: Use tools that are integrated during compilation to insert runtime error-checking mechanisms related to memory safety errors, such as AddressSanitizer (ASan) for C/C++ [REF-1518].
Mappings
Related CVEs, CWEs, and ATT&CK context
Related CWEs
- CWE-415: Double Free
- CWE-416: Use After Free
- CWE-562: Return of Stack Variable Address
- CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
- CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
- CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
- CWE-125: Out-of-bounds Read
- CWE-672: Operation on a Resource after Expiration or Release
- CWE-787: Out-of-bounds Write
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.