CVE-2016-8021 in VirusScan Enterprise Linux
Summary
by MITRE
Improper verification of cryptographic signature vulnerability in Intel Security VirusScan Enterprise Linux (VSEL) 2.0.3 (and earlier) allows remote authenticated users to spoof update server and execute arbitrary code via a crafted input file.
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Analysis
by VulDB Data Team • 12/05/2024
The vulnerability identified as CVE-2016-8021 represents a critical cryptographic signature verification flaw within Intel Security VirusScan Enterprise Linux version 2.0.3 and earlier releases. This weakness stems from inadequate validation of digital signatures used during software update processes, creating a pathway for malicious actors to bypass security controls. The vulnerability specifically affects the update mechanism of the antivirus solution, which is designed to ensure that only legitimate and verified software updates are installed on protected systems.
The technical implementation of this flaw involves the improper handling of cryptographic signatures during the verification process. When the VSEL client receives update files from the designated update server, it should validate the digital signatures to confirm authenticity and integrity. However, the vulnerable implementation fails to properly verify these signatures, allowing attackers to craft malicious update files with forged signatures that appear legitimate to the verification system. This cryptographic weakness aligns with CWE-322, which addresses the issue of improper verification of cryptographic signatures, and falls under the broader category of weak cryptographic implementations that undermine security assurances.
The operational impact of this vulnerability is severe and multifaceted. Remote authenticated users who can access the system with valid credentials can exploit this flaw to impersonate legitimate update servers and deliver malicious code to vulnerable systems. This capability enables attackers to execute arbitrary code with the privileges of the affected service, potentially leading to full system compromise. The vulnerability essentially undermines the trust model that antivirus solutions rely on, allowing attackers to bypass the very security controls designed to protect against malware and other threats. Systems running affected versions become vulnerable to supply chain attacks where attackers can inject malicious payloads into the legitimate update process, making detection more difficult and increasing the attack surface significantly.
This vulnerability directly maps to several ATT&CK techniques including T1070.004 (Indicator Removal on Host) through the ability to execute malicious code without detection, T1566.001 (Phishing: Spearphishing Attachment) by potentially delivering malicious updates through compromised email attachments, and T1021.001 (Remote Services: Remote Desktop Protocol) as attackers may use compromised systems to establish further access. The attack chain typically begins with an authenticated user gaining access to the system, followed by crafting a malicious update file with forged signatures that the vulnerable VSEL client accepts as legitimate. The exploit requires minimal privileges but can result in significant damage due to the trusted nature of the update mechanism.
Mitigation strategies for CVE-2016-8021 focus primarily on immediate patching and system updates to the latest versions of Intel Security VirusScan Enterprise Linux that address the cryptographic verification flaw. Organizations should implement network segmentation and monitoring to detect unusual update activities or connections to unauthorized servers. The implementation of additional signature validation mechanisms, such as certificate pinning or multi-layered verification processes, can provide additional protection. System administrators should also consider implementing network-based firewalls to restrict communication with update servers to only known and trusted endpoints, and enable logging and alerting for update-related activities. Regular security assessments and vulnerability scanning should be conducted to identify systems running vulnerable versions, while maintaining up-to-date threat intelligence to detect potential exploitation attempts. The vulnerability demonstrates the critical importance of proper cryptographic implementation in security products and highlights the need for robust verification mechanisms in all update and distribution systems.