CVE-2014-9744 in PolarSSL
Summary
by MITRE
Memory leak in PolarSSL before 1.3.9 allows remote attackers to cause a denial of service (memory consumption) via a large number of ClientHello messages. NOTE: this identifier was SPLIT from CVE-2014-8628 per ADT3 due to different affected versions.
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Analysis
by VulDB Data Team • 10/31/2017
The vulnerability identified as CVE-2014-9744 represents a critical memory leak issue within PolarSSL cryptographic library versions prior to 1.3.9. This flaw specifically targets the SSL/TLS implementation's handling of ClientHello messages, which are the initial handshake messages sent by clients to servers during the TLS negotiation process. The vulnerability enables remote attackers to exploit the library's memory management functions through repeated transmission of malformed or excessive ClientHello messages, ultimately leading to progressive memory consumption that can result in system resource exhaustion.
The technical root cause of this vulnerability stems from inadequate memory management within PolarSSL's TLS handshake processing routines. When the library receives multiple ClientHello messages without proper cleanup of allocated memory structures, it fails to release previously allocated memory blocks that are associated with each handshake attempt. This memory leak occurs during the SSL/TLS handshake phase where the library allocates memory for processing client certificates, cipher suites, and other handshake parameters. The flaw is particularly dangerous because it allows attackers to continuously send ClientHello messages without triggering any authentication or authorization checks, making the attack vector extremely low privilege and highly effective.
From an operational impact perspective, this vulnerability creates a significant denial of service condition that can affect any system running PolarSSL versions before 1.3.9. The memory consumption grows linearly with each ClientHello message received, potentially leading to complete system memory exhaustion and application crashes. Network services that rely on PolarSSL for secure communications become vulnerable to sustained attacks that can render them unavailable to legitimate users. The vulnerability affects a wide range of applications including web servers, email servers, and other network services that implement TLS encryption using PolarSSL. Attackers can leverage this vulnerability through simple network packet flooding techniques without requiring any special privileges or complex exploitation methods.
The vulnerability aligns with CWE-401, which specifically addresses improper management of dynamic memory allocation, and can be categorized under ATT&CK technique T1499.004 for network denial of service attacks. Organizations using affected PolarSSL versions face significant risk of service disruption, especially in environments where network services are exposed to untrusted networks. The attack can be executed from any network location that can reach the target service, making it particularly dangerous for publicly accessible servers. Security practitioners should note that this vulnerability was separated from CVE-2014-8628 due to differing affected versions, indicating that the memory leak issue was specifically tied to the ClientHello message processing rather than broader SSL/TLS implementation flaws. The recommended mitigation strategy involves immediate upgrade to PolarSSL version 1.3.9 or later, which includes proper memory cleanup routines and enhanced resource management during TLS handshake processing. Additionally, network administrators should implement rate limiting and connection tracking mechanisms to detect and prevent excessive ClientHello message patterns that could indicate exploitation attempts.