CVE-2018-0237 in Advanced Malware Protection
Summary
by MITRE
A vulnerability in the file type detection mechanism of the Cisco Advanced Malware Protection (AMP) for Endpoints macOS Connector could allow an unauthenticated, remote attacker to bypass malware detection. The vulnerability occurs because the software relies on only the file extension for detecting DMG files. An attacker could exploit this vulnerability by sending a DMG file with a nonstandard extension to a device that is running an affected AMP for Endpoints macOS Connector. An exploit could allow the attacker to bypass configured malware detection. Cisco Bug IDs: CSCve34034.
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Analysis
by VulDB Data Team • 01/29/2020
The vulnerability identified as CVE-2018-0237 resides within Cisco Advanced Malware Protection AMP for Endpoints macOS Connector, representing a critical flaw in the software's file type detection methodology. This weakness manifests specifically in how the system processes disk image files, particularly DMG files that are commonly used on macOS platforms for software distribution. The vulnerability stems from the software's over-reliance on file extensions as the sole indicator of file type, creating a fundamental security gap that can be easily exploited by malicious actors. The flaw demonstrates a clear failure in implementing robust file validation mechanisms that should consider multiple file attributes beyond simple extension matching.
The technical implementation of this vulnerability exploits the inherent weakness in the file type detection system by leveraging the predictable nature of file extension-based identification. When the AMP for Endpoints macOS Connector encounters a file, it performs type detection solely based on the file extension rather than examining the actual file structure, magic numbers, or other binary characteristics that would definitively identify the file type. This approach creates a dangerous assumption that file extensions cannot be easily manipulated or forged, which represents a classic security anti-pattern. An attacker can simply rename a malicious executable file to have a .dmg extension, thereby bypassing the detection mechanisms that would normally flag the file as potentially malicious based on its actual content.
The operational impact of this vulnerability extends beyond simple bypass of malware detection, creating a significant risk to endpoint security across affected systems. When an attacker successfully delivers a malicious payload disguised as a legitimate DMG file, the affected AMP connector fails to recognize the true nature of the file, allowing it to execute without proper security screening. This vulnerability directly undermines the core purpose of endpoint protection software, which is designed to prevent unauthorized execution of potentially harmful code. The attack scenario represents a sophisticated social engineering approach combined with technical exploitation, where the attacker leverages the software's trust in file extensions to gain unauthorized access to systems.
This vulnerability aligns with CWE-20, "Improper Input Validation," and demonstrates poor input sanitization practices that have been consistently identified as critical weaknesses in security systems. The flaw also relates to ATT&CK technique T1059.001, "Command and Scripting Interpreter: PowerShell", through the broader category of execution bypass techniques, though the specific method relies more on file type confusion rather than script execution. The weakness creates a pathway for attackers to leverage the trust model inherent in the AMP system, where legitimate file types are assumed safe, allowing malicious code to execute undetected. Organizations relying on this protection mechanism face significant risk of undetected malware installation, potentially leading to data breaches, system compromise, and lateral movement within their networks.
Mitigation strategies should focus on implementing comprehensive file validation that considers multiple file attributes beyond extension matching, including header analysis, file structure examination, and content-based detection methods. The recommended approach involves updating the AMP for Endpoints macOS Connector to a patched version that implements proper file type detection based on actual file content rather than relying solely on extensions. Additionally, organizations should implement layered security controls including network-based file filtering, endpoint detection and response systems, and regular security assessments to identify similar weaknesses in their security infrastructure. The vulnerability underscores the importance of defense in depth strategies and the necessity of implementing multiple independent verification mechanisms to prevent single points of failure in security systems.