CVE-2011-0651 in Iconfidant SSL Server
Summary
by MITRE
Buffer overflow in the key exchange functionality in Icon Labs Iconfidant SSL Server before 1.3.0 allows remote attackers to execute arbitrary code via a client master key packet in which the sum of unspecified length fields is greater than a certain value.
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Analysis
by VulDB Data Team • 01/10/2018
The vulnerability identified as CVE-2011-0651 represents a critical buffer overflow flaw within the Icon Labs Iconfidant SSL Server software version 1.2.9 and earlier. This issue specifically targets the key exchange functionality of the SSL server implementation, creating a pathway for remote attackers to gain unauthorized code execution capabilities. The vulnerability stems from inadequate input validation and boundary checking within the processing of client master key packets, which are essential components in the SSL/TLS handshake process. The flaw manifests when the sum of unspecified length fields within these packets exceeds predetermined thresholds, causing memory corruption that can be exploited to overwrite adjacent memory regions.
The technical implementation of this vulnerability involves the improper handling of variable-length data structures during SSL key exchange operations. When a client establishes a connection with the vulnerable SSL server, it sends a client master key packet containing multiple length fields that should be validated against expected boundaries. However, the Iconfidant SSL Server fails to properly validate the cumulative sum of these length fields, allowing an attacker to craft malicious packets where the total exceeds the allocated buffer space. This buffer overflow condition creates opportunities for attackers to inject and execute arbitrary code on the target system, potentially leading to complete system compromise.
From an operational impact perspective, this vulnerability poses significant risks to organizations relying on Icon Labs Iconfidant SSL Server for secure communications. The remote exploitability means that attackers can target vulnerable systems from anywhere on the network without requiring physical access or prior authentication. Successful exploitation could result in unauthorized access to sensitive data, complete system takeover, and potential lateral movement within network environments. The vulnerability affects the fundamental security of SSL communications, undermining the confidentiality and integrity guarantees that SSL/TLS protocols are designed to provide. Organizations using affected versions face potential data breaches, service disruption, and compliance violations that could have substantial financial and reputational consequences.
The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and reflects patterns commonly found in the MITRE ATT&CK framework under the technique of "Exploitation for Privilege Escalation." The attack surface is particularly concerning given that SSL servers typically operate as critical infrastructure components handling sensitive communications. Organizations should immediately implement the vendor-provided patch for Iconfidant SSL Server version 1.3.0 or later, which addresses the buffer overflow through proper input validation and boundary checking. Additional mitigations include network segmentation to limit exposure, monitoring for suspicious SSL handshake patterns, and implementing intrusion detection systems that can identify malformed key exchange packets. Security teams should also conduct comprehensive vulnerability assessments to identify any other potentially affected systems and ensure proper patch management processes are in place to prevent similar issues in the future.