COMMON WEAKNESS ENUMERATIONIncomplete

CWE-15

External Control of System or Configuration Setting

One or more system settings or configuration elements can be externally controlled by a user.

Abstraction

Base

Structure

Simple

Likelihood of Exploit

Medium

Understand the problem

What is the problem?

One or more system settings or configuration elements can be externally controlled by a user.

Extended description

Allowing external control of system settings can disrupt service or cause an application to behave in unexpected, and potentially malicious ways.

Root cause

How and when does the problem arise?

Lifecycle phase

Implementation

Setting manipulation vulnerabilities occur when an attacker can control values that govern the behavior of the system, manage specific resources, or in some way affect the functionality of the application.

Lifecycle phase

Implementation

REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Risk

What does successful exploitation lead to?

Varies by Context

Affected security scopes: Other

Defence

How is it prevented and fixed?

Architecture and Design

Separation of Privilege

Detail
Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

Implementation · Architecture and Design

Defence to apply across several lifecycle phases

Detail
Because setting manipulation covers a diverse set of functions, any attempt at illustrating it will inevitably be incomplete. Rather than searching for a tight-knit relationship between the functions addressed in the setting manipulation category, take a step back and consider the sorts of system values that an attacker should not be allowed to control.

Implementation · Architecture and Design

Defence to apply across several lifecycle phases

Detail
In general, do not allow user-provided or otherwise untrusted data to control sensitive values. The leverage that an attacker gains by controlling these values is not always immediately obvious, but do not underestimate the creativity of the attacker.

Verification

How is it detected?

Automated Static Analysis

High
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.)