CVE-2023-2650: Medium Vulnerability in OpenSSL

CVE-2023-2650 pertains to an issue in OpenSSL where processing certain specially crafted ASN.1 object identifiers can lead to substantial delays. This vulnerability has been classified with a CVSS score of 6.5, indicating a medium severity level. The risk to organizations includes potential Denial of Service (DoS) due to the lengthy processing times. Applications that rely on the OBJ_obj2txt() function or any OpenSSL subsystems like OCSP, PKCS7/SMIME, CMS, CMP/CRMF, or TS without message size limits are particularly vulnerable.

The impact is significant when large sub-identifiers are processed, as the time complexity of the operation grows quadratically with their size. Such scenarios can lead to severe performance degradation, especially in applications that handle untrusted data. Hence, it is crucial for organizations using OpenSSL to be aware of this vulnerability and take appropriate measures.

The vulnerability was published on May 30, 2023, and impacts OpenSSL versions 1.0.2, 1.1.1, and 3.0.0 through 3.1.0. With a high EPS score of 0.92, it indicates a significant risk of exploitation in real-world scenarios, thus necessitating immediate patching to mitigate potential risks.

Organizations should prioritize patching immediately.

Vulnerability Details

CVE-2023-2650 was identified as a vulnerability in OpenSSL, specifically relating to the processing of ASN.1 object identifiers. The official description states that applications using the OBJ_obj2txt() function or OpenSSL subsystems may face significant delays in message processing. This could potentially lead to a Denial of Service due to the time complexity being O(n^2) with 'n' representing the size of the sub-identifiers in bytes.

The vulnerability affects OpenSSL versions 3.0.0 to 3.0.9 and 3.1.0 up to 3.1.1, while OpenSSL versions 1.1.1 and 1.0.2 are affected only in terms of displaying diverse objects, thus considered less critical. The risk level is classified as medium, with the CVSS score of 6.5 reflecting the potential availability impact.

Technical Analysis

The root cause of CVE-2023-2650 lies in how ASN.1 object identifiers are processed by the OBJ_obj2txt() function. The function translates a given ASN.1 OBJECT IDENTIFIER in DER encoding into its canonical numeric text form. The problem arises when one of the sub-identifiers is excessively large, causing the processing time to increase significantly.

The attack vector for this vulnerability is primarily network-based, as it can be triggered when applications process untrusted data. The attack complexity is low, given that it requires no special privileges, though user interaction is necessary. The availability impact is assessed as high, as prolonged processing can lead to application hang-ups or crashes.

Risk & Impact Analysis

The real-world risk posed by CVE-2023-2650 is significant, especially for applications that handle large volumes of ASN.1 object identifiers. Organizations must consider the potential for Denial of Service attacks, which can disrupt services and affect user experience. The blast radius for this vulnerability could be extensive, especially for services using OpenSSL for TLS communications.

Given the CVSS score of 6.5, organizations should address this vulnerability in their priority patch cycle. The urgency is further emphasized by the high EPS score, indicating a strong likelihood of real-world exploitation. Organizations must take proactive steps to mitigate this risk.

Exploitation Status

Affected Versions

The vulnerability affects OpenSSL versions 1.0.2 (up to 1.0.2zh), 1.1.1 (up to 1.1.1u), and 3.0.0 (up to 3.0.9) and 3.1.0 (up to 3.1.1). If version information is missing, organizations should consider 'All versions prior to vendor patch.'

Mitigation & Remediation

To mitigate the risks associated with CVE-2023-2650, organizations should promptly apply available patches to their OpenSSL installations. Patching OpenSSL to the latest stable version will help protect against this vulnerability. If an immediate patch is not feasible, organizations should implement workarounds such as limiting input size and thoroughly validating ASN.1 object identifiers before processing.

Additionally, organizations should consider conducting a thorough security assessment of their systems, which can include a detailed review of cryptographic operations and usage of the OpenSSL library. For best practices in maintaining security standards, organizations may refer to resources on application security assessment to ensure robust defenses against potential threats.

Detection Guidance

To detect potential exploitation of CVE-2023-2650, organizations should monitor their applications for unusual delays when processing ASN.1 object identifiers. Log indicators that may signify exploitation include high response times or system resource exhaustion when handling ASN.1 data.

AppSecure Threat Intelligence Insight

CVE-2023-2650 highlights the critical importance of maintaining strict input validation and size limits when processing ASN.1 data in OpenSSL. This vulnerability serves as a reminder for security teams to continuously assess the threat landscape surrounding cryptographic libraries and their integration within applications. The trend of vulnerabilities related to cryptographic processing emphasizes the need for organizations to adopt a proactive security stance.

For further insights and strategies on securing cryptographic implementations, organizations can explore our guide on penetration testing methodology and consider engaging in proactive testing to identify potential weaknesses.

Additionally, learning from vulnerabilities like CVE-2023-2650 can help organizations refine their threat modeling and incident response strategies. For comprehensive security assessments, consider adopting a red teaming approach to simulate real-world attacks and discover potential gaps in defenses.