CVE-2016-8620 in macOS
Summary
by MITRE
The globbing feature in curl before version 7.51.0 has a flaw that leads to integer overflow and out-of-bounds read via user controlled input.
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Analysis
by VulDB Data Team • 10/07/2022
The vulnerability identified as CVE-2016-8620 represents a critical flaw in the curl command-line tool that affects versions prior to 7.51.0. This issue resides within the globbing functionality, which allows users to perform file operations using wildcard patterns. The vulnerability manifests when curl processes user-controlled input through globbing patterns, creating a dangerous scenario where malicious input can trigger memory corruption. The flaw specifically exploits integer overflow conditions that occur during the processing of wildcard expansions, leading to unpredictable behavior and potential exploitation. This vulnerability type falls under the category of memory safety issues that can be leveraged for arbitrary code execution or denial of service attacks.
The technical implementation of this vulnerability stems from improper handling of integer arithmetic within curl's globbing subsystem. When processing wildcard patterns, the application performs calculations to determine buffer sizes and memory allocation requirements. An attacker can craft input that causes these calculations to overflow integer values, resulting in insufficient buffer allocation. This overflow condition directly translates to out-of-bounds read operations where the application attempts to access memory locations beyond the allocated buffer boundaries. The vulnerability is particularly dangerous because it allows remote attackers to control the input parameters, making it possible to trigger the overflow condition through network-based interactions or local file manipulation. This flaw is classified as a CWE-190 integer overflow vulnerability, which is a well-documented category of issues that can lead to memory corruption and arbitrary code execution.
The operational impact of CVE-2016-8620 extends beyond simple denial of service scenarios to encompass potential remote code execution capabilities. Systems that utilize curl with globbing features for automated file operations, web scraping, or network communication are at risk when running vulnerable versions. Attackers can exploit this vulnerability in contexts where curl processes untrusted input, such as web applications that use curl for backend operations, automated scripts that handle user uploads, or systems that process file patterns from external sources. The vulnerability is particularly concerning in environments where curl is used with elevated privileges or in security-critical applications. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as it can be exploited through command-line interfaces where curl is invoked with malicious patterns. The impact is amplified in containerized environments or systems where curl is used as part of automated workflows.
Mitigation strategies for CVE-2016-8620 focus primarily on upgrading to curl version 7.51.0 or later, which contains the necessary patches to address the integer overflow and out-of-bounds read conditions. Organizations should prioritize immediate deployment of updated curl versions across all systems where the vulnerable functionality is utilized. Additional defensive measures include implementing input validation and sanitization for any curl operations that process user-controlled data, particularly when globbing patterns are involved. Network administrators should consider restricting access to curl commands in environments where untrusted input might be processed, and implement proper access controls to limit the potential impact of exploitation. Security monitoring should include detection of suspicious curl usage patterns, particularly those involving complex globbing operations or unexpected wildcard expansions. The vulnerability demonstrates the importance of proper integer overflow handling in security-critical applications and reinforces the need for regular security updates and vulnerability management processes. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security fixes for widely-used tools like curl.