CVE-2021-36082 in nDPI
Summary
by MITRE • 07/01/2021
ntop nDPI 3.4 has a stack-based buffer overflow in processClientServerHello.
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Analysis
by VulDB Data Team • 07/04/2021
The vulnerability identified as CVE-2021-36082 affects ntop nDPI version 3.4 and represents a critical stack-based buffer overflow flaw within the processClientServerHello function. This issue resides in the network protocol detection library that ntop uses to analyze and classify network traffic. The vulnerability manifests when the software processes TLS client hello messages, which are the initial handshake packets exchanged between clients and servers during secure communications. The buffer overflow occurs due to insufficient input validation and bounds checking in the function responsible for parsing these handshake messages, creating a potential exploitation vector for remote attackers.
The technical implementation of this vulnerability stems from improper memory management within the processClientServerHello function where the software fails to adequately verify the length of incoming data before copying it into fixed-size stack buffers. When an attacker crafts a malicious TLS client hello message with oversized data fields, the software attempts to copy this data into a buffer that cannot accommodate the excessive input, leading to stack corruption. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a fundamental memory safety issue that has been consistently identified as a high-risk vulnerability in software security assessments. The flaw represents a classic example of how insufficient input validation can lead to arbitrary code execution in network applications.
The operational impact of this vulnerability extends beyond simple denial-of-service scenarios, as it provides potential attackers with the capability to execute arbitrary code on systems running vulnerable versions of ntop nDPI. Network monitoring and intrusion detection systems that rely on nDPI for protocol analysis become particularly vulnerable, as these systems often run with elevated privileges and process large volumes of network traffic from multiple sources. Attackers could leverage this vulnerability to gain unauthorized access to network monitoring infrastructure, potentially compromising the integrity of network traffic analysis and enabling further lateral movement within compromised networks. The vulnerability affects systems where nDPI is integrated into network security appliances, firewalls, and network monitoring solutions that utilize the library for deep packet inspection capabilities.
Mitigation strategies for CVE-2021-36082 should prioritize immediate patching of affected systems, with ntop releasing updated versions that address the buffer overflow through proper input validation and bounds checking mechanisms. Organizations should implement network segmentation and access controls to limit exposure of vulnerable systems, while also considering the deployment of intrusion detection systems that can identify and block malicious TLS handshake packets. The vulnerability aligns with ATT&CK technique T1071.004 Application Layer Protocol: DNS, as it affects network protocol handling within application layer communications. Additionally, implementing proper memory safety practices including stack canaries, address space layout randomization, and heap-based buffer overflow protections can provide defense-in-depth measures. Security teams should also conduct comprehensive vulnerability assessments to identify all systems utilizing vulnerable nDPI versions and establish monitoring procedures to detect potential exploitation attempts targeting this specific buffer overflow vulnerability.