CAPEC Definitions

    CAPEC Definitions / CAPEC-21

    CAPEC-21: Exploitation of Trusted Identifiers

    An adversary guesses, obtains, or rides a trusted identifier (e.g. session ID, resource ID, cookie, etc.) to perform authorized actions under the guise of an authenticated user or service.

    Severity:High
    Possibility:High

    Extended Description

    Attacks leveraging trusted identifiers typically result in the adversary laterally moving within the local network, since users are often allowed to authenticate to systems/applications within the network using the same identifier. This allows the adversary to obtain sensitive data, download/install malware on the system, pose as a legitimate user for social engineering purposes, and more. Attacks on trusted identifiers take advantage of the fact that some software accepts user input without verifying its authenticity. Many server side processes are vulnerable to these attacks because the server to server communications have not been analyzed from a security perspective or the processes "trust" other systems because they are behind a firewall. Similarly, servers that use easy to guess or spoofable schemes for representing digital identity can also be vulnerable. Such systems frequently use schemes without cryptography and digital signatures (or with broken cryptography). Identifiers may be guessed or obtained due to insufficient randomness, poor protection (passed/stored in the clear), lack of integrity (unsigned), or improper correlation with access control policy enforcement points. Exposed configuration and properties files that contain sensitive data may additionally provide an adversary with the information needed to obtain these identifiers. An adversary may also "ride" an identifier via a malicious link, as is the case in Cross Site Request Forgery (CSRF) attacks. Regardless of the attack vector, successful spoofing and impersonation of trusted credentials can lead to an adversary breaking authentication, authorization, and audit controls with the target system or application.

    Mitigations

    Design: utilize strong federated identity such as SAML to encrypt and sign identity tokens in transit.

    Implementation: Use industry standards session key generation mechanisms that utilize high amount of entropy to generate the session key. Many standard web and application servers will perform this task on your behalf.

    Implementation: If the identifier is used for authentication, such as in the so-called single sign on use cases, then ensure that it is protected at the same level of assurance as authentication tokens.

    Implementation: If the web or application server supports it, then encrypting and/or signing the identifier (such as cookie) can protect the ID if intercepted.

    Design: Use strong session identifiers that are protected in transit and at rest.

    Implementation: Utilize a session timeout for all sessions, for example 20 minutes. If the user does not explicitly logout, the server terminates their session after this period of inactivity. If the user logs back in then a new session key is generated.

    Implementation: Verify authenticity of all identifiers at runtime.

    Relationships with other CAPECs

    No related CAPECs found.

    Prerequisites

    Server software must rely on weak identifier proof and/or verification schemes.

    Identifiers must have long lifetimes and potential for reusability.

    Server software must allow concurrent sessions to exist.

    Related Weaknesses

    CWE-290: Authentication Bypass by Spoofing

    CWE-302: Authentication Bypass by Assumed-Immutable Data

    CWE-346: Origin Validation Error

    CWE-539: Use of Persistent Cookies Containing Sensitive Information

    CWE-6: J2EE Misconfiguration: Insufficient Session-ID Length

    CWE-384: Session Fixation

    CWE-664: Improper Control of a Resource Through its Lifetime

    CWE-602: Client-Side Enforcement of Server-Side Security

    CWE-642: External Control of Critical State Data