CVE-2021-40528 is a medium-severity vulnerability in the ElGamal implementation within GnuPG's Libgcrypt library, specifically versions prior to 1.9.4. This vulnerability allows plaintext recovery due to a dangerous interaction between two cryptographic libraries. The risk arises from a specific combination involving the prime and generator defined by the receiver's public key, along with the sender's ephemeral exponents, which could lead to a cross-configuration attack against OpenPGP. With a CVSS score of 5.9, the vulnerability poses a significant risk to organizations relying on this cryptographic implementation.
The vulnerability was published on September 6, 2021, and its status has been modified since its initial disclosure. Organizations using affected versions of Libgcrypt should be aware that the attack vector is network-based, with a high complexity requirement. The lack of required privileges or user interaction makes this vulnerability particularly concerning, as it can be exploited without specific access controls. As such, it is essential for security teams to prioritize remediation efforts to safeguard against potential exploitation.
Given the potential for plaintext recovery, organizations must assess the impact of this vulnerability on their systems. The high confidentiality impact indicates that sensitive data could be at risk if this vulnerability is not addressed promptly. Therefore, organizations should prioritize patching immediately to mitigate the risks associated with CVE-2021-40528.
To understand the urgency of addressing this vulnerability, organizations should consider the context of their deployment. The vulnerability has been classified with a medium exploitability rating, pointing to an increased likelihood of exploitation in the wild. This necessitates a careful evaluation of systems utilizing Libgcrypt as part of a comprehensive risk management strategy.
Vulnerability Details
The official description of CVE-2021-40528 states that the ElGamal implementation in Libgcrypt before version 1.9.4 allows plaintext recovery because of a dangerous combination of the prime defined by the receiver's public key, the generator defined by the receiver's public key, and the sender's ephemeral exponents. This interaction can lead to a cross-configuration attack against OpenPGP.
The CVSS score for this vulnerability is 5.9, categorized as medium severity. The attack vector is network-based, and the attack complexity is high, meaning that an attacker must possess specific conditions to exploit this vulnerability effectively. There are no privileges required for exploitation, and no user interaction is necessary.
The affected product is Libgcrypt, a cryptographic library used in various applications. The vulnerability was published on September 6, 2021, and has been categorized under CWE-327, which relates to the use of a broken or risky cryptographic algorithm.
Technical Analysis
The root cause of CVE-2021-40528 lies in the ElGamal implementation within Libgcrypt. During the interaction between two cryptographic libraries, a specific combination of parameters can lead to the plaintext recovery. This vulnerability is characterized by a high attack complexity, meaning that the attacker must meet certain conditions for successful exploitation.
The attack vector is network-based, indicating that a remote attacker can exploit this vulnerability without physical access to the system. Importantly, the exploitation does not require any privileges or user interaction, which heightens the risks associated with this vulnerability, allowing it to be exploited by unauthenticated users.
In terms of impact, the vulnerability has a high confidentiality impact, as the plaintext recovery could expose sensitive information. However, it does not affect integrity or availability, as indicated by the low scores in those categories. Organizations should monitor for potential attacks exploiting this vulnerability and assess the implications for their systems.
Risk & Impact Analysis
Organizations using Libgcrypt must recognize the real-world risk associated with CVE-2021-40528. The vulnerability's network attack vector and the absence of required privileges mean that it could potentially be exploited with relative ease by malicious actors. Risk to organizations includes unauthorized access to sensitive information, leading to possible data breaches and compliance violations.
The blast radius of this vulnerability is significant, particularly for organizations that handle sensitive data or rely on cryptographic implementations for security. Given the high confidentiality impact, organizations should assess their exposure and prioritize remediation efforts.
With a CVSS score of 5.9 and a medium exploitability rating, organizations should address this vulnerability in their priority patch cycle. The EPSS score further emphasizes the need for vigilance, as it indicates a potential for exploitation in the wild.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected version of Libgcrypt includes all versions prior to 1.9.4. Organizations should verify their installations and ensure they are using the latest version to mitigate the risks associated with this vulnerability.
Mitigation & Remediation
To mitigate the risks associated with CVE-2021-40528, organizations should upgrade Libgcrypt to version 1.9.4 or later. If immediate upgrading is not feasible, consider implementing configuration hardening measures and network controls to limit exposure. Monitoring for unusual activities related to cryptographic operations can also provide insights into potential exploitation attempts.
Organizations should also review their cryptographic libraries and assess the potential impact of similar vulnerabilities in the future. For a comprehensive approach to security, consider engaging in penetration testing to validate the integrity of their cryptographic implementations.
Detection Guidance
Organizations should maintain logs of cryptographic operations and monitor for behavioral anomalies that may indicate exploitation attempts. Key indicators include unexpected plaintext recovery requests or unusual patterns in cryptographic library interactions. Additionally, network signatures associated with known vulnerabilities should be established for proactive detection.
AppSecure Threat Intelligence Insight
CVE-2021-40528 highlights critical vulnerabilities within cryptographic implementations that can lead to serious data exposure. This incident underscores the need for continuous monitoring and proactive security measures in cryptographic operations. Organizations must stay informed about potential vulnerabilities and regularly assess their cryptographic practices.
For further insights into enhancing security practices, organizations may find value in exploring resources on penetration testing methodology or adopting a comprehensive vulnerability management program to systematically address potential weaknesses.
Additionally, organizations can benefit from insights provided by API penetration testing to strengthen security measures around their cryptographic implementations.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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