Buffer Overflow in an API Call
Attack Pattern ID: 8 (Detailed Attack Pattern Completeness: Complete)Typical Severity: HighStatus: Draft
+ Description


This attack targets libraries or shared code modules which are vulnerable to buffer overflow attacks. An attacker who has access to an API may try to embed malicious code in the API function call and exploit a buffer overflow vulnerability in the function's implementation. All clients that make use of the code library thus become vulnerable by association. This has a very broad effect on security across a system, usually affecting more than one software process.

Attack Execution Flow

  1. An attacker can call an API exposed by the target host.

  2. On the probing stage, the attacker injects malicious code using the API call and observes the results. The attacker's goal is to uncover a buffer overflow vulnerability.

  3. The attacker finds a buffer overflow vulnerability, crafts malicious code and injects it through an API call. The attacker can at worst execute remote code on the target host.

+ Attack Prerequisites

The target host exposes an API to the user.

One or more API functions exposed by the target host has a buffer overflow vulnerability.

+ Typical Likelihood of Exploit

Likelihood: High

+ Methods of Attack
  • API Abuse
  • Injection
+ Examples-Instances


A buffer overflow in the FreeBSD utility setlocale (found in the libc module) puts many programs at risk all at once.


A buffer overflow in the Xt library of the X windowing system allows local users to execute commands with root privileges.

+ Attacker Skills or Knowledge Required

Skill or Knowledge Level: Low

An attacker can simply overflow a buffer by inserting a long string into an attacker-modifiable injection vector. The result can be a DoS.

High : Exploiting a buffer overflow to inject malicious code into the stack of a software system or even the heap can require a higher skill level.

+ Solutions and Mitigations

Use a language or compiler that performs automatic bounds checking.

Use secure functions not vulnerable to buffer overflow.

If you have to use dangerous functions, make sure that you do boundary checking.

Compiler-based canary mechanisms such as StackGuard, ProPolice and the Microsoft Visual Studio /GS flag. Unless this provides automatic bounds checking, it is not a complete solution.

Use OS-level preventative functionality. Not a complete solution.

+ Attack Motivation-Consequences
  • Denial of Service
  • Run Arbitrary Code
  • Information Leakage
  • Data Modification
+ Injection Vector

The user supplied data.

+ Payload

The buffer overrun by the attacker.

+ Activation Zone

When the function returns control to the main program, it jumps to the return address portion of the stack frame. Unfortunately that return address may have been overwritten by the overflowed buffer and the address may contain a call to a privileged command or to a malicious code.

+ Payload Activation Impact

The most common is remote code execution.

+ Related Weaknesses
CWE-IDWeakness NameWeakness Relationship Type
120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')Targeted
119Failure to Constrain Operations within the Bounds of a Memory BufferTargeted
118Improper Access of Indexable Resource ('Range Error')Targeted
74Failure to Sanitize Data into a Different Plane ('Injection')Targeted
20Improper Input ValidationTargeted
680Integer Overflow to Buffer OverflowTargeted
733Compiler Optimization Removal or Modification of Security-critical CodeSecondary
697Insufficient ComparisonTargeted
+ Related Attack Patterns
NatureTypeIDNameDescriptionView(s) this relationship pertains toView\(s\)
ChildOfAttack PatternAttack Pattern100Overflow Buffers 
Mechanism of Attack (primary)1000
ParentOfAttack PatternAttack Pattern14Client-side Injection-induced Buffer Overflow 
Mechanism of Attack1000
PeerOfAttack PatternAttack Pattern46Overflow Variables and Tags 
Mechanism of Attack1000
ParentOfAttack PatternAttack Pattern69Target Programs with Elevated Privileges 
Mechanism of Attack1000
+ Relevant Security Requirements

Bound checking should be performed when copying data to a buffer.

+ Related Security Principles
  • Reluctance to trust

  • Defense in Depth

+ Purposes
  • Penetration
+ CIA Impact
Confidentiality Impact: HighIntegrity Impact: HighAvailability Impact: High
+ Technical Context
Architectural Paradigms
+ References
G. Hoglund and G. McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. February 2004.

CWE - Buffer Errors

+ Content History
G. Hoglund and G. McGraw. Exploiting Software: How to Break Code. Addison-Wesley, February 2004.Cigital, Inc2007-03-01
Eric DalciCigital, Inc2007-02-13Fleshed out content to CAPEC schema from the original descriptions in "Exploiting Software"
Sean BarnumCigital, Inc2007-03-05Review and revise
Richard StruseVOXEM, Inc2007-03-26Review and feedback leading to changes in Description
Sean BarnumCigital, Inc2007-04-13Modified pattern content according to review and feedback