CVE-2018-7161 in Node.js
Summary
by MITRE
All versions of Node.js 8.x, 9.x, and 10.x are vulnerable and the severity is HIGH. An attacker can cause a denial of service (DoS) by causing a node server providing an http2 server to crash. This can be accomplished by interacting with the http2 server in a manner that triggers a cleanup bug where objects are used in native code after they are no longer available. This has been addressed by updating the http2 implementation.
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Analysis
by VulDB Data Team • 02/19/2020
This vulnerability affects Node.js versions 8.x, 9.x, and 10.x where the http2 server implementation contains a critical flaw that can be exploited to cause denial of service conditions. The vulnerability stems from improper handling of object cleanup within the native code components of the http2 module, creating a scenario where objects are accessed after they have been deallocated or destroyed. This type of memory safety issue represents a classic use-after-free vulnerability pattern that has been categorized under CWE-416. The flaw specifically manifests when an attacker interacts with the http2 server in a particular manner that triggers the problematic cleanup code path.
The technical execution of this vulnerability involves exploiting the http2 server's handling of connection states and object lifecycle management. When legitimate http2 connections are established and subsequently terminated in specific sequences, the native code components fail to properly manage reference counting or object disposal. This results in the native code attempting to access memory locations that have already been freed or are no longer valid. The issue is particularly dangerous because it occurs in the core http2 implementation, making it accessible to any attacker who can establish connections to the affected Node.js server. The vulnerability has been classified as HIGH severity due to the potential for complete service disruption and the relative ease of exploitation.
The operational impact of CVE-2018-7161 extends beyond simple service interruption to potentially compromise the availability and stability of Node.js applications that rely on http2 functionality. Systems running affected Node.js versions become vulnerable to attacks that can cause immediate server crashes, requiring manual restarts and potentially leading to extended downtime. This vulnerability directly maps to the ATT&CK technique T1499.004 for network denial of service, as it enables attackers to disrupt services through protocol-level exploitation. Organizations using Node.js servers with http2 capabilities face significant risk of service degradation or complete outages, particularly in high-traffic environments where http2 connections are frequently established and terminated. The vulnerability affects both server-side applications and any Node.js-based services that utilize the http2 protocol for communication.
Mitigation strategies for this vulnerability center on immediate patching of Node.js installations to versions that contain the corrected http2 implementation. The fix addresses the root cause by implementing proper object lifecycle management within the native code components, ensuring that cleanup operations occur before objects are accessed. Organizations should prioritize updating their Node.js installations to versions that include the security patch, with particular attention to production environments that handle http2 traffic. Additionally, implementing network-level protections such as rate limiting and connection monitoring can help detect and mitigate exploitation attempts. The vulnerability highlights the importance of proper memory management in native code components and the need for comprehensive testing of protocol implementations, especially those handling complex connection states and object lifecycles. System administrators should also consider implementing intrusion detection systems to monitor for unusual http2 connection patterns that might indicate exploitation attempts.