CVE-2018-3738 in protobufjs
Summary
by MITRE
protobufjs is vulnerable to ReDoS when parsing crafted invalid .proto files.
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Analysis
by VulDB Data Team • 02/17/2020
The vulnerability identified as CVE-2018-3738 affects the protobufjs library, which is a popular JavaScript implementation for working with Google Protocol Buffers. This security flaw represents a Regular Expression Denial of Service (ReDoS) vulnerability that specifically manifests when the library processes maliciously crafted .proto files. The issue stems from the library's use of regular expressions in its parsing logic, which can be exploited by attackers to cause significant performance degradation or complete system unresponsiveness.
The technical root cause of this vulnerability lies in the improper handling of regular expressions within the protobufjs parsing mechanism. When an attacker crafts a specially designed .proto file containing malicious regular expression patterns, the library's parsing function becomes susceptible to catastrophic backtracking. This occurs because certain regular expressions can match input strings in exponential time complexity, causing the parser to consume excessive CPU resources and potentially leading to denial of service conditions. The vulnerability is particularly dangerous because it can be triggered through normal file parsing operations without requiring special privileges or complex attack vectors.
The operational impact of CVE-2018-3738 extends beyond simple performance degradation to potentially compromise entire applications that rely on protobufjs for data processing. Systems utilizing this library for parsing user-provided or third-party protocol buffer definitions become vulnerable to attacks that can cause service disruption, resource exhaustion, and in severe cases, complete application unavailability. This vulnerability affects any application that accepts and processes .proto files from untrusted sources, making it particularly concerning for web applications, API gateways, and services that handle user uploads or external data feeds. The risk is amplified in environments where protobufjs is used for parsing configuration files or data structures that might be manipulated by malicious actors.
Mitigation strategies for this vulnerability involve updating to patched versions of the protobufjs library where the problematic regular expressions have been either replaced with more secure alternatives or properly escaped to prevent catastrophic backtracking. Organizations should implement comprehensive dependency management practices to ensure all components are kept current with security patches. Additionally, input validation and sanitization measures should be strengthened to prevent processing of untrusted .proto files, and monitoring systems should be deployed to detect unusual parsing behavior that might indicate exploitation attempts. From a security framework perspective, this vulnerability aligns with CWE-1321 which specifically addresses Regular Expression vulnerabilities, and can be mapped to ATT&CK technique T1496 for resource exhaustion attacks. Network segmentation and application whitelisting can provide additional defense-in-depth measures to limit the potential impact of such attacks.