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Weakness · High

CWE-121: Stack-based Buffer Overflow

What it is

A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

Likelihood of exploit: High12 exploited in the wildMITRE CWE 4.19.1

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

What an attacker can do

  • Modify Memory (Availability, Integrity, Confidentiality, Access Control, Other)
  • 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)
  • Other (Integrity, Confidentiality, Availability, Access Control, Other)

How to prevent it

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.

Architecture and Design

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

Implementation

  • Implement and perform bounds checking on input.
  • Do not use dangerous functions such as gets. Use safer, equivalent functions which check for boundary errors.

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 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++.

CWE-121 on MITRE's CWE site

Exploited in the wild: 12 CVEs

Vulnerabilities caused by CWE-121 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.