CVE-2020-3308 in Firepower Threat Defense
Summary
by MITRE
A vulnerability in the Image Signature Verification feature of Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker with administrator-level credentials to install a malicious software patch on an affected device. The vulnerability is due to improper verification of digital signatures for patch images. An attacker could exploit this vulnerability by crafting an unsigned software patch to bypass signature checks and loading it on an affected device. A successful exploit could allow the attacker to boot a malicious software patch image.
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Analysis
by VulDB Data Team • 10/15/2020
The vulnerability identified as CVE-2020-3308 resides within the Image Signature Verification mechanism of Cisco Firepower Threat Defense software, representing a critical security weakness that undermines the integrity protection of network defense systems. This flaw specifically affects Cisco Firepower devices that operate with software versions prior to 6.4.0.4, making them susceptible to targeted attacks that compromise the device's firmware integrity. The vulnerability stems from inadequate validation procedures that fail to properly verify digital signatures associated with software patches, creating an exploitable gap in the security architecture of these network appliances.
The technical exploitation of this vulnerability requires an attacker to possess administrator-level credentials, which establishes a baseline for authentication requirements but does not prevent the execution of malicious code through signature bypass mechanisms. The flaw manifests when the system processes software patch images, where the improper verification logic allows unsigned patches to pass validation checks. This occurs because the signature verification process fails to adequately validate the cryptographic integrity of patch files, enabling attackers to craft malicious software patches that appear legitimate to the system's verification mechanisms. The vulnerability directly relates to CWE-330, which addresses insufficient randomness in security-critical operations, and CWE-347, which covers improper verification of cryptographic signatures. Attackers can leverage this weakness to install unauthorized software modifications that could alter the device's operational behavior, potentially enabling persistent backdoor access or complete system compromise.
From an operational perspective, the impact of CVE-2020-3308 extends beyond simple patch installation to represent a fundamental threat to network security infrastructure. When successfully exploited, the vulnerability allows attackers to load malicious software patches that can modify the device's boot process, potentially enabling persistent access to the network defense system. This capability creates a persistent threat vector that could remain undetected for extended periods, as the malicious code would be integrated into the device's normal operational processes. The vulnerability also aligns with ATT&CK technique T1078, which covers valid accounts and T1547, which covers boot or logon initialization scripts, as the malicious patch could be designed to execute during system boot processes. Network defenders face significant challenges in detecting such attacks because the malicious modifications would appear to be legitimate software updates from the system's perspective.
Mitigation strategies for CVE-2020-3308 should prioritize immediate software updates to Cisco Firepower Threat Defense versions 6.4.0.4 and later, which contain the necessary signature verification improvements. Organizations must also implement strict access controls and monitoring of administrative activities to minimize the risk of credential compromise. Network segmentation and privileged access management solutions can help reduce the attack surface by limiting the ability of attackers to reach administrative interfaces. Additionally, implementing network-based monitoring for unusual patch installation activities and conducting regular security audits of network defense systems can help detect potential exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date security patches and the critical need for robust cryptographic verification mechanisms in network security appliances. Security teams should also consider implementing automated patch management systems that can quickly deploy security updates across multiple devices while maintaining detailed audit trails of all software modifications.