COMMON ATTACK PATTERN ENUMERATION AND CLASSIFICATIONLive MITRE record

CAPEC-96

Block Access to Libraries

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.

Abstraction

Detailed

Typical severity

Medium

Likelihood of attack

Medium

Understand the attack

What is this attack pattern?

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.

Execution flow

How does the attack proceed, step by step?

1

Explore

Attack step

Determine what external libraries the application accesses.
2

Experiment

Attack step

Block access to the external libraries accessed by the application.

Attack step

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

Attack step

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.

Requirements

What does the attack require?

Prerequisites

  • An application requires access to external libraries.
  • An attacker has the privileges to block application access to external libraries.

Skills required

  • Low: Knowledge of how to block access to libraries, as well as knowledge of how to leverage the resulting state of the application based on the failed call.

Resources required

Not stated in the MITRE record.

Impact

What does a successful attack lead to?

Alter Execution Logic

Affected scopes: Availability

Other

Affected scopes: Confidentiality

Bypass Protection Mechanism

Affected scopes: Confidentiality, Access Control, Authorization

Defence

How is it prevented and mitigated?

1
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.

Real world

MITRE example instances

Example instance 1Detail
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 application. 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.