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Weakness · High

CWE-124: Buffer Underwrite ('Buffer Underflow')

What it is

The product writes to a buffer using an index or pointer that references a memory location prior to the beginning of the buffer.

Likelihood of exploit: Medium1 exploited in the wildMITRE CWE 4.19.1

Severity (our rating)
High
Likelihood of exploit
Medium
Introduced during
Implementation
Exploited in the wild
1 known exploited CVE

What an attacker can do

  • Modify Memory (Integrity, Availability, Confidentiality, Access Control, Other)
  • DoS: Crash, Exit, or Restart (Integrity, 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

Requirements

  • Choose a language that is not susceptible to these issues.

Implementation

  • All calculated values that are used as index or for pointer arithmetic should be validated to ensure that they are within an expected range.

How to find it

  • 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-124 on MITRE's CWE site

Exploited in the wild: 1 CVE

Vulnerabilities caused by CWE-124 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.