CVE-2018-18314 in TimesTen In-Memory Database
Summary
by MITRE
Perl before 5.26.3 has a buffer overflow via a crafted regular expression that triggers invalid write operations.
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Analysis
by VulDB Data Team • 07/30/2024
This vulnerability exists within the perl interpreter version 5.26.2 and earlier, representing a critical buffer overflow condition that can be exploited through maliciously crafted regular expressions. The flaw occurs during the processing of regular expressions when the interpreter fails to properly validate input lengths, leading to memory corruption through invalid write operations. This vulnerability falls under the CWE-121 buffer overflow category, specifically classified as a heap-based buffer overflow where attacker-controlled data can overwrite adjacent memory locations. The issue arises from insufficient bounds checking in the regular expression engine, particularly when handling complex patterns that trigger memory allocation calculations based on user input. Attackers can leverage this vulnerability by crafting specific regular expression patterns that cause the perl interpreter to allocate insufficient memory buffers, resulting in memory corruption that can lead to arbitrary code execution. The vulnerability is particularly dangerous because perl is widely used in web applications, system administration scripts, and network security tools where regular expressions are commonly employed. According to ATT&CK framework, this vulnerability maps to T1059.007 Command and Scripting Interpreter: Perl, where adversaries can use this weakness to execute malicious code on compromised systems. The operational impact extends beyond simple denial of service as this vulnerability can be exploited remotely in web applications that process user input through perl regular expressions, potentially allowing full system compromise. The vulnerability affects systems running perl versions prior to 5.26.3, making it relevant to a broad range of enterprise environments where perl scripting is prevalent, including web servers, network security appliances, and automated system management tools.
The technical exploitation of this buffer overflow requires careful crafting of regular expression patterns that can trigger the memory corruption during pattern compilation or execution phases. The vulnerability manifests when the perl interpreter encounters specific regex constructs that cause integer overflow or underflow in memory allocation calculations, leading to buffer overflows in heap memory regions. The flaw is particularly insidious because it can be triggered through seemingly benign regular expression patterns that appear harmless but contain subtle constructs that cause the interpreter to miscalculate memory requirements. During normal operation, perl's regex engine maintains internal buffers for pattern matching operations, but when these buffers are improperly sized due to malformed input, the subsequent memory writes can overwrite critical program data structures or function return addresses. This type of vulnerability can be classified as a use-after-free or heap corruption issue that can be leveraged for privilege escalation attacks. The exploitation typically involves crafting a regular expression that causes the interpreter to allocate a buffer that is too small for the actual data to be written, resulting in overwrites of adjacent memory regions. Security researchers have noted that this vulnerability is particularly dangerous in environments where perl is used for processing untrusted input from web forms, network packets, or file contents, as these scenarios are common attack vectors for remote code execution.
Mitigation strategies for CVE-2018-18314 primarily focus on upgrading perl installations to version 5.26.3 or later, which contains the necessary patches to prevent the buffer overflow condition. Organizations should conduct comprehensive inventory audits to identify all systems running vulnerable perl versions and prioritize patching based on risk assessment of affected applications. System administrators should implement regular security scanning procedures to detect vulnerable perl installations in their environments, particularly in web servers, network security tools, and automated scripting environments. Additional defensive measures include implementing input validation controls at application boundaries to sanitize regular expression inputs before processing, using perl's built-in taint mode to detect potentially malicious input, and employing web application firewalls to monitor for suspicious regex patterns. The vulnerability also underscores the importance of secure coding practices in interpreter development, emphasizing the need for robust bounds checking and memory management in regular expression engines. Organizations should consider implementing runtime protections such as address space layout randomization and stack canaries to make exploitation more difficult even if patches are not immediately available. Security monitoring should include detection of unusual memory allocation patterns or potential buffer overflow attempts in perl processes, which can be achieved through log analysis and anomaly detection systems. According to industry best practices, this vulnerability demonstrates the critical importance of keeping interpreter and scripting language components up to date, as these foundational elements often serve as attack vectors for more sophisticated exploits. The remediation process should also include security awareness training for developers who work with perl scripting to understand the risks associated with regular expression processing and the importance of input validation in preventing such vulnerabilities.