Reliance on Cookies without Validation and Integrity Checking

Incomplete Base

Structure: Simple

Description

The product relies on the existence or values of cookies when performing security-critical operations, but it does not properly ensure that the setting is valid for the associated user.

Common Consequences 2

Scope: ConfidentialityIntegrityAvailability

Impact: Modify Application DataExecute Unauthorized Code or Commands

Attackers can easily modify cookies, within the browser or by implementing the client-side code outside of the browser. Reliance on cookies without detailed validation and integrity checking can allow attackers to bypass authentication, conduct injection attacks such as SQL injection and cross-site scripting, or otherwise modify inputs in unexpected ways.

Scope: Access Control

Impact: Gain Privileges or Assume Identity

It is dangerous to use cookies to set a user's privileges. The cookie can be manipulated to escalate an attacker's privileges to an administrative level.

Detection Methods 1

Automated Static AnalysisHigh

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.)

Potential Mitigations 4

Phase: Architecture and Design

Avoid using cookie data for a security-related decision.

Phase: Implementation

Perform thorough input validation (i.e.: server side validation) on the cookie data if you're going to use it for a security related decision.

Phase: Architecture and Design

Add integrity checks to detect tampering.

Phase: Architecture and Design

Protect critical cookies from replay attacks, since cross-site scripting or other attacks may allow attackers to steal a strongly-encrypted cookie that also passes integrity checks. This mitigation applies to cookies that should only be valid during a single transaction or session. By enforcing timeouts, you may limit the scope of an attack. As part of your integrity check, use an unpredictable, server-side value that is not exposed to the client.

Demonstrative Examples 1

ID : DX-61

The following code excerpt reads a value from a browser cookie to determine the role of the user.

Code Example:Bad
Java
java

It is easy for an attacker to modify the "role" value found in the locally stored cookie, allowing privilege escalation.

Observed Examples 1

CVE-2008-5784e-dating application allows admin privileges by setting the admin cookie to 1.

Modes of Introduction

Architecture and Design

Implementation

Related Attack Patterns

Related Weaknesses

ChildOf:

External Control of Critical State Data (CWE-642)

ChildOf:

Incorrect Resource Transfer Between Spheres (CWE-669)

ChildOf:

Client-Side Enforcement of Server-Side Security (CWE-602)

Taxonomy Mapping

Software Fault Patterns

Notes

RelationshipThis problem can be primary to many types of weaknesses in web applications. A developer may perform proper validation against URL parameters while assuming that attackers cannot modify cookies. As a result, the program might skip basic input validation to enable cross-site scripting, SQL injection, price tampering, and other attacks..