CVE-2018-3739 in https-proxy-agent
Summary
by MITRE
https-proxy-agent before 2.1.1 passes auth option to the Buffer constructor without proper sanitization, resulting in DoS and uninitialized memory leak in setups where an attacker could submit typed input to the 'auth' parameter (e.g. JSON).
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Analysis
by VulDB Data Team • 02/17/2020
The vulnerability identified as CVE-2018-3739 affects the https-proxy-agent package version 2.1.1 and earlier, representing a critical security flaw that stems from improper input validation within the authentication handling mechanism. This issue manifests when the auth option is passed directly to the Buffer constructor without adequate sanitization, creating a dangerous condition that can be exploited by malicious actors who control the authentication parameters. The vulnerability exists in environments where attackers can submit typed input to the auth parameter, such as in JSON-based configurations or API endpoints that accept user-provided authentication data. The flaw operates at the core level of how authentication credentials are processed, making it particularly dangerous for applications that rely on proxy agent functionality for network communication.
The technical exploitation of this vulnerability occurs through the direct passage of unvalidated authentication data into the Buffer constructor, which creates two primary security impacts. The first impact is denial of service, where malformed or specially crafted authentication parameters can cause the application to crash or become unresponsive due to improper buffer handling. The second and more insidious impact involves uninitialized memory leakage, where the lack of sanitization allows attackers to potentially access memory regions that contain sensitive data from previous operations. This memory leakage can expose credentials, session information, or other confidential data that may have been stored in the affected memory areas. The vulnerability directly maps to CWE-129, which addresses improper validation of buffer sizes, and CWE-126, which covers buffer under-read conditions, making it a compound issue that affects both input validation and memory management.
The operational impact of CVE-2018-3739 extends beyond simple service disruption, as it creates potential data exposure risks that can compromise entire application security postures. Applications using vulnerable versions of https-proxy-agent may experience unexpected crashes during authentication processing, leading to service unavailability and potential business disruption. The uninitialized memory leakage aspect poses a more subtle but serious threat, as attackers can potentially extract sensitive information from memory dumps or through careful exploitation techniques. This vulnerability is particularly concerning in enterprise environments where proxy agents are commonly used for network traffic management and where authentication credentials are frequently processed. The attack surface is broad since many applications and frameworks utilize proxy agents for outbound connections, making this vulnerability potentially widespread across various software ecosystems.
Mitigation strategies for CVE-2018-3739 should prioritize immediate patching of the https-proxy-agent package to version 2.1.1 or later, which contains the necessary sanitization fixes for the auth parameter handling. Organizations should conduct comprehensive vulnerability assessments to identify all systems and applications that utilize vulnerable versions of the package, particularly those that process user-provided authentication data through proxy configurations. Network monitoring should be enhanced to detect potential exploitation attempts, and input validation mechanisms should be strengthened to prevent malformed data from reaching the buffer processing layer. Additionally, implementing proper access controls and least privilege principles for proxy agent configurations can reduce the potential impact of exploitation. From an ATT&CK framework perspective, this vulnerability aligns with techniques related to privilege escalation and credential access, as it can potentially enable attackers to extract sensitive information from memory. Security teams should also consider implementing runtime protections and memory integrity checks to detect and prevent unauthorized memory access patterns that may indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper input sanitization in security-critical components and the potential consequences of inadequate validation in core system functions.