CVE-2020-7768 in grpc
Summary
by MITRE • 11/11/2020
The package grpc before 1.24.4; the package @grpc/grpc-js before 1.1.8 are vulnerable to Prototype Pollution via loadPackageDefinition.
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Analysis
by VulDB Data Team • 12/05/2020
The vulnerability identified as CVE-2020-7768 affects the gRPC library ecosystem, specifically impacting versions prior to 1.24.4 for the core grpc package and 1.1.8 for the @grpc/grpc-js package. This represents a critical security flaw that undermines the integrity of JavaScript applications relying on gRPC for communication. The vulnerability manifests through the loadPackageDefinition function, which serves as a crucial component for defining and loading protocol buffer packages within the gRPC framework. When exploited, this flaw allows attackers to manipulate the prototype of objects within the application's memory space, potentially leading to arbitrary code execution or privilege escalation. The issue stems from inadequate input validation and sanitization within the package definition loading mechanism, creating a pathway for malicious actors to inject malicious properties into the prototype chain of objects used by the gRPC library.
The technical implementation of this prototype pollution vulnerability occurs when the loadPackageDefinition function processes package definitions without properly validating or sanitizing the keys and values within the package structure. This allows attackers to inject properties that can modify the behavior of existing objects in memory, particularly affecting the Object.prototype which is fundamental to JavaScript's inheritance model. When gRPC loads package definitions, it iterates through the provided structure and assigns properties to objects, but fails to check for potentially malicious keys that could override existing prototype properties. This flaw aligns with CWE-471, which specifically addresses the vulnerability of software to modifications of objects in the prototype chain, and represents a direct threat to the security of applications that depend on gRPC for service communication.
The operational impact of CVE-2020-7768 extends beyond simple data corruption, potentially enabling attackers to execute arbitrary code within the context of applications using vulnerable gRPC versions. Applications that rely on gRPC for microservices communication, API gateways, or distributed systems become particularly vulnerable since the prototype pollution can be leveraged to manipulate core application behavior. The vulnerability is especially concerning in environments where gRPC is used for inter-service communication, as it could allow an attacker to manipulate service responses, bypass authentication mechanisms, or escalate privileges within the service mesh. The attack vector typically involves sending malicious package definitions to services that use gRPC for communication, where the vulnerable loadPackageDefinition function processes these definitions and pollutes the prototype chain with attacker-controlled properties.
Mitigation strategies for this vulnerability require immediate version updates to gRPC 1.24.4 or later for the core package and @grpc/grpc-js 1.1.8 or later for the JavaScript implementation. Organizations should conduct comprehensive audits of their application dependencies to identify all systems using vulnerable versions of gRPC, particularly focusing on microservices architectures where gRPC is commonly employed. The remediation process should include not only updating the gRPC library but also implementing proper input validation and sanitization within applications that process external package definitions. Security teams should consider implementing runtime monitoring to detect unusual object property modifications and establish security policies that prevent the loading of untrusted package definitions. Additionally, the vulnerability demonstrates the importance of following secure coding practices and adhering to the principle of least privilege when implementing communication frameworks, as highlighted by ATT&CK technique T1068 which addresses local privilege escalation through application vulnerabilities. Organizations should also consider implementing dependency management tools that automatically scan for vulnerable libraries and provide alerts when outdated versions are detected in their software supply chain.