COMMON ATTACK PATTERN ENUMERATION AND CLASSIFICATIONLive MITRE record

CAPEC-196

Session Credential Falsification through Forging

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.

Abstraction

Standard

Typical severity

Medium

Likelihood of attack

Medium

Understand the attack

What is this attack pattern?

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.

Execution flow

How does the attack proceed, step by step?

1

Explore

Analyze and Understand Session IDs

The attacker finds that the targeted application use session credentials to identify legitimate users.

Techniques used

  • An attacker makes many anonymous connections and records the session IDs.
  • An attacker makes authorized connections and records the session tokens or credentials.
2

Experiment

Create Session IDs.

Attackers craft messages containing their forged credentials in GET, POST request, HTTP headers or cookies.

Techniques used

  • The attacker manipulates the HTTP request message and adds their forged session IDs in to the requests or cookies.
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.

Techniques used

  • 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.

Requirements

What does the attack require?

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: 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.

Impact

What does a successful attack lead to?

Modify Data

Affected scopes: Integrity

Read Data

Affected scopes: Confidentiality

Execute Unauthorized Commands

Affected scopes: Authorization

Gain Privileges

Affected scopes: Accountability, Authentication, Authorization, Non-Repudiation

Bypass Protection Mechanism

Affected scopes: Access Control, Authorization

Defence

How is it prevented and mitigated?

1
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.
2
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.

Real world

MITRE example instances

Example instance 1Detail
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/<script>document.cookie="sessionid=0123456789";</script> 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.
CAPEC-196: Session Credential Falsification through Forging — DayBreach Saldırı Sözlüğü · DayBreach