CVE-2015-3165 in PostgreSQL
Summary
by MITRE
Double free vulnerability in PostgreSQL before 9.0.20, 9.1.x before 9.1.16, 9.2.x before 9.2.11, 9.3.x before 9.3.7, and 9.4.x before 9.4.2 allows remote attackers to cause a denial of service (crash) by closing an SSL session at a time when the authentication timeout will expire during the session shutdown sequence.
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Analysis
by VulDB Data Team • 05/19/2022
The CVE-2015-3165 vulnerability represents a critical double free error in PostgreSQL database systems that affects multiple version branches including 9.0.x through 9.4.x. This flaw occurs during the SSL session termination process when authentication timeouts are about to expire, creating a scenario where memory management functions attempt to free the same memory block twice. The vulnerability is particularly dangerous because it can be exploited remotely by attackers who do not require authentication credentials, making it an attractive target for denial of service attacks against database servers. The double free condition arises from improper handling of memory allocation and deallocation sequences during the SSL shutdown procedure, specifically when the system encounters a timing window where authentication timeouts coincide with session closure operations.
The technical implementation of this vulnerability stems from the database's handling of SSL connections and authentication timeouts within the PostgreSQL backend process. When an SSL session is terminated and an authentication timeout is pending, the system's memory management routines execute a sequence where the same memory pointer is passed to the free function twice. This occurs because the SSL shutdown sequence contains logic flaws that do not properly track memory allocations and deallocations during the authentication timeout window. The vulnerability is classified under CWE-415 as a double free condition, which represents a common memory corruption flaw that can lead to unpredictable behavior including application crashes and potential memory corruption. The flaw manifests when the database server processes the final stages of an SSL connection shutdown, where it attempts to clean up authentication-related memory structures that are already in the process of being freed.
The operational impact of CVE-2015-3165 extends beyond simple service disruption to potentially compromise the overall stability and reliability of PostgreSQL deployments. Remote attackers can exploit this vulnerability to cause database servers to crash repeatedly, leading to extended downtime and service unavailability for legitimate users. The vulnerability's remote exploitability means that attackers can target database systems from outside the network perimeter without requiring valid credentials, making it particularly dangerous in production environments where database availability is critical. Organizations running affected PostgreSQL versions face significant risk of denial of service attacks that can be executed with minimal resources and technical expertise. The timing aspect of the vulnerability makes it especially challenging to defend against, as it requires precise coordination with authentication timeout events, which can be difficult to predict and mitigate through conventional means. This flaw directly impacts the availability aspect of the CIA triad, potentially causing cascading failures in applications that depend on database connectivity.
Mitigation strategies for CVE-2015-3165 focus primarily on upgrading to patched PostgreSQL versions where the memory management routines have been corrected to prevent the double free condition. Organizations should immediately implement version upgrades to PostgreSQL 9.0.20, 9.1.16, 9.2.11, 9.3.7, or 9.4.2 respectively, depending on their current deployment. Additional protective measures include implementing network-level firewalls to restrict access to PostgreSQL ports, monitoring for unusual connection patterns that might indicate exploitation attempts, and configuring authentication timeouts to minimize the window during which the vulnerability can be exploited. Security teams should also consider implementing intrusion detection systems that can identify suspicious SSL connection termination patterns. The vulnerability's classification under the ATT&CK framework as a denial of service technique demonstrates its potential to be used in broader attack campaigns targeting database infrastructure. Regular security assessments and vulnerability scanning should be conducted to ensure that all PostgreSQL installations remain patched against this and similar memory corruption vulnerabilities, as the double free pattern represents a persistent threat vector in database software implementations.