CVE-2019-11808 in Ratpack
Summary
by MITRE
Ratpack versions before 1.6.1 generate a session ID using a cryptographically weak PRNG in the JDK's ThreadLocalRandom. This means that if an attacker can determine a small window for the server start time and obtain a session ID value, they can theoretically determine the sequence of session IDs.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 09/12/2023
The vulnerability identified as CVE-2019-11808 affects Ratpack applications running versions prior to 1.6.1, where the framework employs a cryptographically weak pseudorandom number generator for session identifier generation. This flaw resides in the underlying JDK's ThreadLocalRandom implementation which does not provide cryptographically secure random number generation suitable for security-sensitive operations. The issue stems from the use of a predictable random number generation mechanism that lacks the entropy required for generating secure session identifiers, creating a significant weakness in the application's session management security posture.
The technical flaw manifests when Ratpack applications generate session identifiers using ThreadLocalRandom instead of a cryptographically secure random number generator such as SecureRandom. This approach allows attackers to potentially reconstruct the sequence of session IDs if they can determine a narrow time window during which the server was started and obtain at least one valid session ID from that session. The vulnerability is classified under CWE-330 as the use of insufficiently random values and represents a direct violation of the principle of using cryptographically strong random number generators for security-critical operations. The weakness creates a path for session prediction attacks where an attacker can exploit the predictable nature of the random number generation to compromise session integrity.
The operational impact of this vulnerability extends beyond simple session hijacking scenarios, as it fundamentally undermines the security of authenticated sessions within Ratpack applications. Attackers who can determine the server startup time window and obtain a single session ID can theoretically predict subsequent session IDs, potentially enabling them to impersonate legitimate users and gain unauthorized access to protected resources. This vulnerability affects applications that rely on Ratpack's default session management behavior and could lead to complete compromise of user sessions, particularly in environments where session identifiers are exposed through URL parameters or cookies. The risk is amplified in scenarios where applications are deployed in predictable environments or where server startup times can be easily determined through reconnaissance activities.
Mitigation strategies for CVE-2019-11808 primarily involve upgrading to Ratpack version 1.6.1 or later, which addresses the vulnerable random number generation implementation. Organizations should also consider implementing additional security controls such as session regeneration upon authentication, implementing proper session timeout mechanisms, and employing additional layers of authentication such as multi-factor authentication to reduce the attack surface. Security teams should conduct thorough vulnerability assessments to identify all applications running vulnerable versions of Ratpack and ensure proper patch management procedures are in place. The vulnerability aligns with ATT&CK technique T1548.002 which involves exploiting weak session management to maintain access to systems, and represents a classic example of how improper random number generation can compromise authentication systems. Organizations should also consider implementing session binding mechanisms and additional monitoring for suspicious session activity to detect potential exploitation attempts.