DetailedSeverity: Very HighCAPEC-592

CAPEC-592: Stored XSS

Description

An adversary utilizes a form of Cross-site Scripting (XSS) where a malicious script is persistently stored within the data storage of a vulnerable web application as valid input.

Likelihood of attack: High
Typical severity: Very High
Abstraction: DetailedA low-level, detailed pattern, often for a particular technology.

Mechanism of attack: Inject Unexpected Items

Prerequisites

An application that leverages a client-side web browser with scripting enabled.
An application that fails to adequately sanitize or encode untrusted input.
An application that stores information provided by the user in data storage of some kind.

Skills required

MediumRequires the ability to write scripts of varying complexity and to inject them through user controlled fields within the application.

Consequences

Confidentiality
Read Data
A successful Stored XSS attack can enable an adversary to exfiltrate sensitive information from the application.
ConfidentialityAuthorizationAccess Control
Gain Privileges
A successful Stored XSS attack can enable an adversary to elevate their privilege level and access functionality they should not otherwise be allowed to access.
ConfidentialityIntegrityAvailability
Execute Unauthorized Commands
A successful Stored XSS attack can enable an adversary run arbitrary code of their choosing, thus enabling a complete compromise of the application.
Integrity
Modify Data
A successful Stored XSS attack can allow an adversary to tamper with application data.

Mitigations

Use browser technologies that do not allow client-side scripting.
Utilize strict type, character, and encoding enforcement.
Ensure that all user-supplied input is validated before being stored.

Related weaknesses (CWE)

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Related attack patterns

Parent

CAPEC-63Cross-Site Scripting (XSS)Standard

More specific patterns

Consequences

Confidentiality

Read Data

A successful Stored XSS attack can enable an adversary to exfiltrate sensitive information from the application.

ConfidentialityAuthorizationAccess Control

Gain Privileges

A successful Stored XSS attack can enable an adversary to elevate their privilege level and access functionality they should not otherwise be allowed to access.

ConfidentialityIntegrityAvailability

Execute Unauthorized Commands

A successful Stored XSS attack can enable an adversary run arbitrary code of their choosing, thus enabling a complete compromise of the application.

Integrity

Modify Data

A successful Stored XSS attack can allow an adversary to tamper with application data.