CVE-2022-2576 in Californium
Summary
by MITRE • 07/29/2022
In Eclipse Californium version 2.0.0 to 2.7.2 and 3.0.0-3.5.0 a DTLS resumption handshake falls back to a DTLS full handshake on a parameter mismatch without using a HelloVerifyRequest. Especially, if used with certificate based cipher suites, that results in message amplification (DDoS other peers) and high CPU load (DoS own peer). The misbehavior occurs only with DTLS_VERIFY_PEERS_ON_RESUMPTION_THRESHOLD values larger than 0.
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Analysis
by VulDB Data Team • 08/28/2022
The vulnerability described in CVE-2022-2576 represents a critical security flaw in the Eclipse Californium implementation of the Datagram Transport Layer Security protocol. This issue affects versions 2.0.0 through 2.7.2 and 3.0.0 to 3.5.0 of the software library, creating a significant operational risk for systems relying on DTLS resumption handshakes. The flaw manifests specifically when certificate-based cipher suites are employed, creating conditions that enable both denial of service and resource exhaustion attacks. The vulnerability stems from improper handling of parameter mismatches during the DTLS resumption process, which should normally trigger a HelloVerifyRequest mechanism to prevent such scenarios.
The technical implementation flaw occurs when the DTLS resumption handshake encounters parameter inconsistencies that would typically warrant a HelloVerifyRequest response to validate the client's identity and prevent spoofing attempts. Instead, the system automatically reverts to a full DTLS handshake without this crucial verification step. This behavior becomes particularly dangerous when the DTLS_VERIFY_PEERS_ON_RESUMPTION_THRESHOLD parameter is configured with values greater than zero, as it enables the specific conditions that trigger the vulnerable code path. The absence of proper verification creates a scenario where malicious actors can exploit the system by sending malformed handshake requests that cause the server to perform unnecessary computations and resource allocation.
The operational impact of this vulnerability extends beyond simple service disruption to encompass both distributed denial of service capabilities against peer systems and local denial of service conditions that exhaust the server's computational resources. Message amplification occurs because the system processes multiple handshake messages without proper validation, leading to exponential resource consumption that can overwhelm network connections and processing capabilities. The high CPU load generated by this behavior creates a significant burden on the server, potentially causing legitimate requests to fail due to resource exhaustion. This vulnerability directly relates to CWE-310, which addresses cryptographic weaknesses, and specifically targets improper handling of cryptographic parameters in TLS/DTLS implementations.
The attack vectors enabled by this vulnerability align with several techniques documented in the MITRE ATT&CK framework, particularly those related to resource exhaustion and denial of service operations. Adversaries can leverage this flaw to perform automated attacks against DTLS-enabled services, causing cascading failures that impact the availability of networked applications. The vulnerability's exploitation requires minimal sophistication, making it particularly dangerous in environments where automated scanning and attack tools are prevalent. Organizations using Eclipse Californium in security-critical applications face substantial risk of service degradation or complete unavailability when this vulnerability is present in their deployments.
Effective mitigations for this vulnerability require immediate patching of affected Eclipse Californium versions to the latest releases that contain the necessary fixes for proper DTLS resumption handling. System administrators should also implement monitoring to detect unusual patterns of DTLS handshake activity that might indicate exploitation attempts. Configuration changes should include careful review of the DTLS_VERIFY_PEERS_ON_RESUMPTION_THRESHOLD parameter settings to avoid triggering the vulnerable code path. Additionally, network-level protections such as rate limiting and connection tracking can help mitigate the impact of potential attacks. Organizations should also consider implementing intrusion detection systems that can identify the specific handshake patterns associated with this vulnerability and alert security teams to potential exploitation attempts.