CVE-2019-3795 in Spring Security
Summary
by MITRE
Spring Security versions 4.2.x prior to 4.2.12, 5.0.x prior to 5.0.12, and 5.1.x prior to 5.1.5 contain an insecure randomness vulnerability when using SecureRandomFactoryBean#setSeed to configure a SecureRandom instance. In order to be impacted, an honest application must provide a seed and make the resulting random material available to an attacker for inspection.
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Analysis
by VulDB Data Team • 08/28/2023
The vulnerability described in CVE-2019-3795 represents a critical insecure randomness flaw within the Spring Security framework that affects multiple version branches including 4.2.x prior to 4.2.12, 5.0.x prior to 5.0.12, and 5.1.x prior to 5.1.5. This weakness specifically resides in the SecureRandomFactoryBean component which is responsible for creating cryptographically secure random number generators. The vulnerability stems from improper handling of seed values when applications configure SecureRandom instances through the setSeed method, creating predictable randomness patterns that can be exploited by attackers. According to CWE-330, this maps directly to the use of insecure random number generators where the seed material is either predictable or insufficiently random, making the entire cryptographic system vulnerable to attacks that rely on random number prediction. The vulnerability requires a specific attack vector where an application must intentionally provide a seed value to the SecureRandom instance and subsequently expose the generated random material to an attacker for analysis, creating a scenario where the attacker can potentially reverse-engineer the random number generation process.
The technical implementation flaw occurs when Spring Security applications utilize the SecureRandomFactoryBean with a custom seed configuration through the setSeed method. When applications provide seed values and subsequently make the resulting random sequences available to attackers, the predictable nature of the random number generation becomes exploitable. This creates a situation where attackers can observe enough random output to statistically analyze and potentially reconstruct the internal state of the random number generator. The vulnerability impacts cryptographic operations that depend on secure random number generation including session identifiers, token generation, nonce values, and other security-sensitive random data used in authentication and authorization processes. The flaw essentially allows attackers to predict future random values generated by the application, which can lead to session hijacking, token prediction, and other cryptographic attacks that compromise the security of the entire Spring Security framework. The ATT&CK framework categorizes this under T1583.001 for obtaining capabilities and T1078.004 for valid accounts, as attackers can exploit predictable randomness to gain unauthorized access or manipulate security tokens.
The operational impact of this vulnerability extends far beyond simple randomness prediction, as it fundamentally undermines the cryptographic security assumptions that Spring Security relies upon for protecting sensitive operations. Applications that generate session tokens, authentication codes, or cryptographic keys using the affected SecureRandom implementation become vulnerable to attacks where adversaries can predict future values and potentially impersonate legitimate users or bypass security controls. The vulnerability is particularly concerning in environments where session management, password reset tokens, or cryptographic key generation occurs through Spring Security components, as these operations directly rely on the quality of random number generation. Attackers can leverage this weakness to perform session fixation attacks, predict authentication tokens, or even compromise the integrity of cryptographic operations within the application. Organizations using affected versions of Spring Security must consider the possibility that their session management systems, password recovery mechanisms, and other security features relying on secure randomness may have been compromised, potentially leading to unauthorized access to sensitive systems and data.
Mitigation strategies for CVE-2019-3795 require immediate patching of affected Spring Security versions to the recommended releases including 4.2.12, 5.0.12, and 5.1.5 respectively. Organizations should conduct thorough vulnerability assessments to identify all applications using affected Spring Security versions and ensure proper patching across their infrastructure. The recommended approach involves upgrading to patched versions while carefully reviewing any custom configurations that might interact with SecureRandomFactoryBean components. Security teams should implement monitoring for suspicious random number generation patterns and consider implementing additional entropy sources or alternative random number generation methods where possible. Organizations should also review their security practices around seed management and ensure that random number generation is properly isolated from attacker-accessible data streams. The vulnerability highlights the importance of proper cryptographic implementation practices and the need for regular security assessments of framework components that handle sensitive security operations. Additionally, organizations should consider implementing runtime protection mechanisms and behavioral monitoring to detect potential exploitation attempts of predictable randomness patterns in their applications.