CVE-2017-15132 in Dovecot
Summary
by MITRE
A flaw was found in dovecot 2.0 up to 2.2.33 and 2.3.0. An abort of SASL authentication results in a memory leak in dovecot's auth client used by login processes. The leak has impact in high performance configuration where same login processes are reused and can cause the process to crash due to memory exhaustion.
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Analysis
by VulDB Data Team • 02/02/2023
The vulnerability identified as CVE-2017-15132 represents a memory leak condition affecting dovecot versions ranging from 2.0 through 2.2.33 and 2.3.0, specifically within the authentication client component utilized by login processes. This flaw manifests when SASL authentication attempts are abruptly terminated, creating a scenario where allocated memory is not properly released back to the system. The issue is particularly significant in high-performance server configurations where login processes are designed for reuse, as the memory leak compounds over time. According to CWE-401, this vulnerability falls under memory management flaws, specifically representing a classic memory leak pattern where resources are acquired but never properly deallocated. The ATT&CK framework categorizes this under privilege escalation and resource exhaustion techniques, as the vulnerability can be exploited to consume system resources and potentially cause service disruption.
The technical mechanism behind this vulnerability involves the authentication client's handling of aborted SASL sessions within dovecot's login process architecture. When an authentication attempt is terminated prematurely, the memory allocated for the authentication context fails to be properly freed, resulting in gradual memory consumption. In environments where the same login processes are maintained and reused across multiple authentication requests, this memory leak becomes progressively more severe. The vulnerability affects the core authentication infrastructure, making it particularly dangerous for mail servers that handle high volumes of concurrent authentication requests. The memory exhaustion ultimately leads to process crashes, which can result in complete service unavailability for legitimate users attempting to access mail services.
The operational impact of CVE-2017-15132 extends beyond simple resource consumption to encompass service reliability and availability concerns. In production environments, particularly those utilizing dovecot for email services, this vulnerability can cause cascading failures where authentication processes become unresponsive or crash entirely. The memory leak typically occurs in scenarios involving high authentication throughput, such as busy mail servers handling thousands of concurrent connections or automated authentication attempts. Organizations relying on dovecot for their mail infrastructure face potential denial of service conditions where legitimate users cannot access their mail accounts due to authentication process failures. The vulnerability is especially problematic in environments where process reuse is implemented as an optimization strategy, since the memory leak accumulates over time rather than occurring as a one-time event.
Mitigation strategies for CVE-2017-15132 primarily focus on immediate software updates to versions that contain the fix for the memory leak issue. Organizations should prioritize upgrading dovecot installations to versions 2.2.34 or 2.3.1, which include patches addressing the authentication client memory management flaw. System administrators should also implement monitoring solutions to track memory usage patterns in authentication processes, enabling early detection of potential memory exhaustion conditions. Process restart procedures can serve as a temporary workaround, though this approach is not sustainable for production environments. Additionally, implementing rate limiting and connection pooling mechanisms can help reduce the frequency of authentication attempts that might trigger the memory leak condition. The vulnerability highlights the importance of proper resource management in authentication systems and underscores the need for regular security updates in critical infrastructure components. Organizations should also consider implementing intrusion detection systems to monitor for unusual authentication patterns that might indicate exploitation attempts.