CVE-2018-3736 in https-proxy-agent
Summary
by MITRE
https-proxy-agent passes unsanitized options to Buffer(arg) resulting in DoS and uninitialized memory leak.
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Analysis
by VulDB Data Team • 03/22/2023
The vulnerability identified as CVE-2018-3736 affects the https-proxy-agent npm package, which is commonly used in node.js applications to handle proxy connections. This issue stems from improper input validation within the package's handling of proxy options, specifically when these options are passed directly to the Buffer constructor without adequate sanitization. The flaw exists in the way the package processes user-provided proxy configuration parameters, creating a dangerous condition where malicious input can be exploited to cause system instability.
The technical implementation of this vulnerability occurs when the https-proxy-agent module receives proxy options that contain unsanitized data structures or values. When these unsanitized parameters reach the Buffer constructor, they can trigger unexpected behavior in the underlying JavaScript engine. The vulnerability manifests through two primary attack vectors: denial of service and uninitialized memory exposure. The DoS aspect occurs when malformed proxy options cause the application to crash or become unresponsive, while the uninitialized memory leak results from the Buffer constructor receiving invalid arguments that lead to memory being allocated without proper initialization.
From an operational impact perspective, this vulnerability can affect any application that relies on https-proxy-agent for proxy handling, particularly those in enterprise environments where proxy configurations are frequently used for network security and traffic management. The vulnerability can be exploited by attackers who gain the ability to influence proxy options, potentially through configuration injection attacks or by manipulating application inputs that are subsequently passed to the proxy agent. This creates a significant risk for applications handling sensitive data or operating in regulated environments where availability and data integrity are critical.
The vulnerability maps to CWE-129, which addresses improper validation of input buffers, and CWE-128, which covers incorrect handling of buffer overruns. From an ATT&CK framework perspective, this vulnerability aligns with T1059.001 for command and script injection, as attackers could potentially manipulate proxy configurations to execute unintended code. Additionally, it relates to T1499.004 for network denial of service, since the DoS component directly impacts system availability. Organizations should prioritize updating their https-proxy-agent dependencies to versions that properly sanitize proxy options before passing them to the Buffer constructor, implementing input validation at multiple layers, and monitoring for unusual proxy configuration changes that might indicate exploitation attempts.
The remediation strategy involves upgrading to patched versions of the https-proxy-agent package where proper input sanitization has been implemented. Security teams should conduct comprehensive dependency audits to identify all applications using vulnerable versions and implement automated monitoring for proxy configuration changes. Additionally, organizations should consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts. The vulnerability highlights the importance of proper input validation in JavaScript applications, particularly when dealing with user-provided data that gets processed through low-level system functions like Buffer constructors.