CAPEC-19: Embedding Scripts within Scripts

MITRE CAPEC attack pattern

Description

An adversary leverages the capability to execute their own script by embedding it within other scripts that the target software is likely to execute due to programs' vulnerabilities that are brought on by allowing remote hosts to execute scripts.

Where this sits in the chain

A finding maps to a weakness (CWE), a weakness is exploited by an attack pattern (CAPEC), and an attack pattern shows up in ATT&CK as observed adversary behaviour. This page is the middle hop.

Weaknesses exploited: CWE-284

ATT&CK techniques: T1027.009, T1546.004, T1546.016

Prerequisites

• Target software must be able to execute scripts, and also grant the adversary privilege to write/upload scripts.

Skills required

• Low: To load malicious script into open, e.g. world writable directory
• Medium: Executing remote scripts on host and collecting output

Consequences

• Confidentiality, Integrity, Availability: Execute Unauthorized Commands
• Confidentiality, Access Control, Authorization: Gain Privileges

Mitigations

• Use browser technologies that do not allow client side scripting.
• Utilize strict type, character, and encoding enforcement.
• Server side developers should not proxy content via XHR or other means. If a HTTP proxy for remote content is setup on the server side, the client's browser has no way of discerning where the data is originating from.
• Ensure all content that is delivered to client is sanitized against an acceptable content specification.
• Perform input validation for all remote content.
• Perform output validation for all remote content.
• Disable scripting languages such as JavaScript in browser
• Session tokens for specific host

Source

• MITRE CAPEC CAPEC-19