CVE-2019-10196 in http-proxy-agent
Summary
by MITRE • 03/20/2021
A flaw was found in http-proxy-agent, prior to version 2.1.0. It was discovered http-proxy-agent passes an auth option to the Buffer constructor without proper sanitization. This could result in a Denial of Service through the usage of all available CPU resources and data exposure through an uninitialized memory leak in setups where an attacker could submit typed input to the auth parameter.
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Analysis
by VulDB Data Team • 04/03/2021
The vulnerability identified as CVE-2019-10196 resides within the http-proxy-agent npm package, affecting versions prior to 2.1.0. This flaw represents a critical security issue that demonstrates poor input validation practices in network proxy handling components. The vulnerability specifically targets the authentication parameter processing within the proxy agent implementation, where untrusted input flows directly into core JavaScript buffer construction mechanisms without adequate sanitization measures. The affected component operates as a middleware layer that facilitates HTTP proxy connections, making it a potential attack vector in environments where proxy configurations are dynamically set or user-controlled.
The technical exploitation of this vulnerability occurs through the improper handling of the auth option parameter when passed to the Buffer constructor. This flaw allows attackers to craft malicious authentication data that, when processed by the vulnerable code, triggers unintended behavior in the underlying JavaScript engine. The buffer constructor in Node.js accepts various input types including strings, arrays, and other data structures, but when these inputs are not properly validated, they can cause the JavaScript engine to allocate excessive memory or trigger CPU-intensive operations. The vulnerability stems from CWE-129, which addresses improper validation of buffer length parameters, and CWE-131, which covers incorrect calculation of buffer sizes. The specific nature of the flaw creates a scenario where the buffer construction process becomes computationally expensive and memory-hungry.
The operational impact of this vulnerability manifests as a potential denial of service condition that can consume all available CPU resources on the affected system. When an attacker submits maliciously crafted authentication data, the proxy agent enters a loop of resource-intensive buffer operations that can exhaust system resources and prevent legitimate operations from completing. Additionally, the vulnerability exposes data through uninitialized memory leaks that occur when the Buffer constructor receives unvalidated input. This memory exposure can lead to information disclosure where sensitive data from memory locations may be inadvertently leaked to the attacker. The combination of resource exhaustion and data exposure creates a multi-faceted threat that can compromise both system availability and confidentiality. According to ATT&CK framework, this vulnerability maps to T1499.004 for network denial of service and T1567.002 for credential access through compromised proxy configurations.
Mitigation strategies for CVE-2019-10196 require immediate version updates to http-proxy-agent 2.1.0 or later, which includes proper input sanitization and validation of authentication parameters. Organizations should implement comprehensive dependency scanning procedures to identify all instances of vulnerable packages within their codebases and container images. Security teams must also consider implementing network segmentation and access controls to limit exposure of proxy configurations to untrusted inputs. The fix addresses the root cause by properly validating the auth parameter before passing it to the Buffer constructor, ensuring that all input conforms to expected data types and length restrictions. Additional defensive measures include monitoring for unusual CPU usage patterns and implementing rate limiting on proxy configuration updates to prevent exploitation attempts. Organizations should also review their proxy agent configurations to ensure that authentication data is properly sanitized at multiple layers of their network infrastructure, as recommended by security best practices and industry standards for secure coding practices.