CWE-825: Expired Pointer Dereference

Extended Description

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.

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.

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.

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

Effectiveness: Moderate

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].