Block Access to Libraries
Attack Pattern ID: 96 (Standard Attack Pattern Completeness: Complete)Typical Severity: MediumStatus: Draft
+ Description


An application typically makes calls to functions that are a part of libraries external to the application. These libraries may be part of the operating system or they may be third party libraries. It is possible that the application does not handle situations properly where access to these libraries has been blocked. Depending on the error handling within the application, blocked access to libraries may leave the system in an insecure state that could be leveraged by an attacker.

Attack Execution Flow

  1. Determine what external libraries the application accesses.

  2. Block access to the external libraries accessed by the application.

  3. Monitor the behavior of the system to see if it goes into an insecure/inconsistent state.

  4. If the system does go into an insecure/inconsistent state, leverage that to obtain information about the system functionality or data, elevate access control, etc. The rest of this attack will depend on the context and the desired goal.

+ Attack Prerequisites

An application requires access to external libraries.

An attacker has the priviliges to block application access to external libraries.

+ Typical Likelihood of Exploit

Likelihood: Medium

+ Methods of Attack
  • API Abuse
  • Modification of Resources
+ Examples-Instances


A web-based system uses a third party cryptographic random number generation library that derives entropy from machine's hardware. This library is used in generation of user session ids used by the applicatoin. If the library is inaccessible, the application instead uses a software based weak pseudo random number generation library. An attacker of the system blocks access of the application to the third party cryptographic random number generation library (by renaming it). The application in turn uses the weak pseudo random number generation library to generate session ids that are predictable. An attacker then leverages this weakness to guess a session id of another user to perform a horizontal elevation of privilege escalation and gain access to another user's account.

+ Attacker Skills or Knowledge Required

Skill or Knowledge Level: Low

+ Solutions and Mitigations

Ensure that application handles situations where access to APIs in external libraries is not available securely. If the application cannot continue its execution safely it should fail in a consistent and secure fashion.

+ Attack Motivation-Consequences
  • Denial of Service
  • Information Leakage
  • Privilege Escalation
+ Related Weaknesses
CWE-IDWeakness NameWeakness Relationship Type
589Call to Non-ubiquitous APITargeted
227Failure to Fulfill API Contract ('API Abuse')Targeted
+ Related Attack Patterns
NatureTypeIDNameDescriptionView(s) this relationship pertains toView\(s\)
ChildOfAttack PatternAttack Pattern176Configuration/Environment manipulation 
Mechanism of Attack (primary)1000
+ Related Security Principles
  • Failing Securely

+ Purposes
  • Exploitation
+ CIA Impact
Confidentiality Impact: LowIntegrity Impact: LowAvailability Impact: High
+ Technical Context
Architectural Paradigms
+ Content History
Sean BarnumCigital, Inc.2007-03-25Identified priority for pattern creation
Evgeny LebanidzeCigital, Inc.,2007-03-21Fleshed out content for pattern
Sean BarnumCigital, Inc2007-04-16Review and revise