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Weakness · High

CWE-122: Heap-based Buffer Overflow

What it is

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

Likelihood of exploit: High33 exploited in the wildMITRE CWE 4.19.1

Severity (our rating)
High
Likelihood of exploit
High
Introduced during
Implementation
Exploited in the wild
33 known exploited CVEs

What an attacker can do

  • DoS: Crash, Exit, or Restart (Availability)
  • DoS: Resource Consumption (CPU) (Availability)
  • DoS: Resource Consumption (Memory) (Availability)
  • Execute Unauthorized Code or Commands (Integrity, Confidentiality, Availability, Access Control, Other)
  • Bypass Protection Mechanism (Integrity, Confidentiality, Availability, Access Control, Other)
  • Modify Memory (Integrity, Confidentiality, Availability, Access Control)
  • Other (Integrity, Confidentiality, Availability, Access Control, Other)

How to prevent it

General

  • Pre-design: Use a language or compiler that performs automatic bounds checking.

Architecture and Design

  • Use an abstraction library to abstract away risky APIs. Not a complete solution.

Operation

  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
  • Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code. Examples include Address Space Layout Randomization (ASLR) and Position-Independent Executables (PIE). Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as "rebasing" (for Windows) and "prelinking" (for Linux) using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking. For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND.
  • Use OS-level preventative functionality. This is not a complete solution, but it provides some defense in depth.

Implementation

  • Implement and perform bounds checking on input.
  • Do not use dangerous functions such as gets. Look for their safe equivalent, which checks for the boundary.

How to find it

  • Fuzzing. Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.
  • 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++.

CWE-122 on MITRE's CWE site

Exploited in the wild: 33 CVEs

Vulnerabilities caused by CWE-122 that attackers have used, from CISA's Known Exploited Vulnerabilities catalog, newest first.

All known exploited vulnerabilities

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Source: MITRE Common Weakness Enumeration, CWE version 4.19.1. CWE is a trademark of The MITRE Corporation.