COMMON WEAKNESS ENUMERATIONIncomplete

CWE-822

Untrusted Pointer Dereference

The product obtains a value from an untrusted source, converts this value to a pointer, and dereferences the resulting pointer.

Abstraction

Base

Structure

Simple

Likelihood of Exploit

Medium

Understand the problem

What is the problem?

The product obtains a value from an untrusted source, converts this value to a pointer, and dereferences the resulting pointer.

Extended description

An attacker can supply a pointer for memory locations that the product is not expecting. If the pointer is dereferenced for a write operation, the attack might allow modification of critical state variables, cause a crash, or execute code. If the dereferencing operation is for a read, then the attack might allow reading of sensitive data, cause a crash, or set a variable to an unexpected value (since the value will be read from an unexpected memory location). There are several variants of this weakness, including but not necessarily limited to: - The untrusted value is directly invoked as a function call. - In OS kernels or drivers where there is a boundary between "userland" and privileged memory spaces, an untrusted pointer might enter through an API or system call (see CWE-781 for one such example). - Inadvertently accepting the value from an untrusted control sphere when it did not have to be accepted as input at all. This might occur when the code was originally developed to be run by a single user in a non-networked environment, and the code is then ported to or otherwise exposed to a networked environment.

Root cause

How and when does the problem arise?

Lifecycle phase

Implementation

Risk

What does successful exploitation lead to?

Read Memory

Affected security scopes: Confidentiality

If the untrusted pointer is used in a read operation, an attacker might be able to read sensitive portions of memory.
DoS: Crash, Exit, or Restart

Affected security scopes: Availability

If the untrusted pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" or larger than expected by a read or write operation, the application may terminate unexpectedly.
Execute Unauthorized Code or CommandsModify Memory

Affected security scopes: Integrity, Confidentiality, Availability

If the untrusted pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.

Defence

How is it prevented and fixed?

  • Follow secure coding guidelines for input handling and boundary checking.
  • Enforce strict security reviews and automated static analysis (SAST) checks.

Verification

How is it detected?

Automated Static Analysis

High
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

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].

Crafted inputs are necessary to reach the code containing the error, such as generated by fuzzers. Also, these tools may reduce performance, and they only report the error condition - not the original mistake that led to the error.