An attacker creates a false but functional session credential in order to gain or usurp access to a service. Session credentials allow users to identify themselves to a service after an initial authentication without needing to resend the authentication information (usually a username and password) with every message. If an attacker is able to forge valid session credentials they may be able to bypass authentication or piggy-back off some other authenticated user's session. This attack differs from Reuse of Session IDs and Session Sidejacking attacks in that in the latter attacks an attacker uses a previous or existing credential without modification while, in a forging attack, the attacker must create their own credential, although it may be based on previously observed credentials.

How do you prevent CAPEC-196?

Implementation: Use session IDs that are difficult to guess or brute-force: One way for the attackers to obtain valid session IDs is by brute-forcing or guessing them. By choosing session identifiers that are sufficiently random, brute-forcing or guessing becomes very difficult.

What weaknesses does CAPEC-196 target?

CAPEC-196 exploits 2 CWE weaknesses, including CWE-384 (Session Fixation), CWE-664 (Improper Control of a Resource Through its Lifetime).

How severe is CAPEC-196?

MITRE rates CAPEC-196 as Medium severity with medium likelihood of attack.

CAPEC-196: Session Credential Falsification through Forging

Overview

CAPEC-196 (Session Credential Falsification through Forging) is a standard-level attack pattern catalogued by MITRE in the Common Attack Pattern Enumeration and Classification (CAPEC). It describes a recurring method attackers use to exploit software weaknesses.

How the attack works

The phases an attacker typically follows to carry out this attack.

Step 1
Explore
[Analyze and Understand Session IDs] The attacker finds that the targeted application use session credentials to identify legitimate users.
- An attacker makes many anonymous connections and records the session IDs.
- An attacker makes authorized connections and records the session tokens or credentials.
Step 2
Experiment
[Create Session IDs.] Attackers craft messages containing their forged credentials in GET, POST request, HTTP headers or cookies.
- The attacker manipulates the HTTP request message and adds their forged session IDs in to the requests or cookies.
Step 3
Exploit
[Abuse the Victim's Session Credentials] The attacker fixates falsified session ID to the victim when victim access the system. Once the victim has achieved a higher level of privilege, possibly by logging into the application, the attacker can now take over the session using the forged session identifier.
- The attacker loads the predefined or predicted session ID into their browser and browses to protected data or functionality.
- The attacker loads the predefined or predicted session ID into their software and utilizes functionality with the rights of the victim.

What the attacker needs

Prerequisites

The targeted application must use session credentials to identify legitimate users. Session identifiers that remains unchanged when the privilege levels change. Predictable session identifiers.

Skills required

Medium skill: Forge the session credential and reply the request.

Resources required

Attackers may require tools to craft messages containing their forged credentials, and ability to send HTTP request to a web application.

Consequences

What a successful CAPEC-196 attack can achieve.

Modify Data

Affects: Integrity

Read Data

Affects: Confidentiality

Execute Unauthorized Commands

Affects: Authorization

Run Arbitrary Code

Gain Privileges

Affects: Accountability, Authentication, Authorization, Non-Repudiation

Bypass Protection Mechanism

Affects: Access Control, Authorization

How to mitigate it

Defenses that reduce the risk of CAPEC-196.

Implementation: Use session IDs that are difficult to guess or brute-force: One way for the attackers to obtain valid session IDs is by brute-forcing or guessing them. By choosing session identifiers that are sufficiently random, brute-forcing or guessing becomes very difficult.
Implementation: Regenerate and destroy session identifiers when there is a change in the level of privilege: This ensures that even though a potential victim may have followed a link with a fixated identifier, a new one is issued when the level of privilege changes.

Examples

This example uses client side scripting to set session ID in the victim's browser. The JavaScript code document.cookie="sessionid=0123456789" fixates a falsified session credential into victim's browser, with the help of crafted a URL link. http://www.example.com/ document.cookie="sessionid=0123456789"; A similar example uses session ID as an argument of the URL. http://www.example.com/index.php/sessionid=0123456789 Once the victim clicks the links, the attacker may be able to bypass authentication or piggy-back off some other authenticated victim's session.

The CWE weaknesses that CAPEC-196 exploits.

How this attack relates to others in the CAPEC hierarchy.

Parent

CAPEC-21: Exploitation of Trusted Identifiers

Child

Can precede

Terminology & mappings

Mapped taxonomies

ATTACK: Access Token Manipulation: Create Process with Token (1134.002)
ATTACK: Access Token Manipulation: Make and Impersonate Token (1134.003)
ATTACK: Forge Web Credentials (1606)

Frequently asked questions

Common questions about CAPEC-196.

What is CAPEC-196?: An attacker creates a false but functional session credential in order to gain or usurp access to a service. Session credentials allow users to identify themselves to a service after an initial authentication without needing to resend the authentication information (usually a username and password) with every message. If an attacker is able to forge valid session credentials they may be able to bypass authentication or piggy-back off some other authenticated user's session. This attack differs from Reuse of Session IDs and Session Sidejacking attacks in that in the latter attacks an attacker uses a previous or existing credential without modification while, in a forging attack, the attacker must create their own credential, although it may be based on previously observed credentials.
How does a Session Credential Falsification through Forging attack work?: It typically unfolds over 3 phases. It begins with: [Analyze and Understand Session IDs] The attacker finds that the targeted application use session credentials to identify legitimate users.
How do you prevent CAPEC-196?: Implementation: Use session IDs that are difficult to guess or brute-force: One way for the attackers to obtain valid session IDs is by brute-forcing or guessing them. By choosing session identifiers that are sufficiently random, brute-forcing or guessing becomes very difficult.
What weaknesses does CAPEC-196 target?: CAPEC-196 exploits 2 CWE weaknesses, including CWE-384 (Session Fixation), CWE-664 (Improper Control of a Resource Through its Lifetime).
How severe is CAPEC-196?: MITRE rates CAPEC-196 as Medium severity with medium likelihood of attack.

References

Attack-pattern data is sourced from the MITRE CAPEC catalog (v3.9). Weakness associations link to the corresponding CWE entries on RadicalNotion.AI.