CVE-2019-1982 in Firepower Threat Defense Software
Summary
by MITRE
A vulnerability in the HTTP traffic filtering component of Cisco Firepower Threat Defense Software, Cisco FirePOWER Services Software for ASA, and Cisco Firepower Management Center Software could allow an unauthenticated, remote attacker to bypass filtering protections. The vulnerability is due to improper handling of HTTP requests, including those communicated over a secure HTTPS connection, that contain maliciously crafted headers. An attacker could exploit this vulnerability by sending malicious requests to an affected device. An exploit could allow the attacker to bypass filtering and deliver malicious requests to protected systems, allowing attackers to deliver malicious content that would otherwise be blocked.
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Analysis
by VulDB Data Team • 11/27/2024
The vulnerability identified as CVE-2019-1982 represents a critical flaw in Cisco's network security infrastructure, specifically within the HTTP traffic filtering mechanisms of Firepower Threat Defense Software, FirePOWER Services Software for ASA, and Firepower Management Center Software. This weakness fundamentally undermines the integrity of network traffic inspection and filtering capabilities that organizations rely upon to protect their digital assets from malicious content. The vulnerability stems from inadequate validation and processing of HTTP headers, creating a pathway for attackers to circumvent security controls that are designed to block harmful traffic patterns and content.
The technical implementation of this vulnerability manifests through improper handling of HTTP requests that contain specially crafted headers, regardless of whether the communication occurs over standard HTTP or secure HTTPS protocols. This flaw demonstrates a failure in input validation and sanitization processes within the filtering engine, where the system does not adequately inspect or reject malformed or malicious header structures that could contain encoded payloads or instructions designed to manipulate the filtering behavior. The vulnerability specifically affects the way the software processes header fields that may contain unexpected characters, encoding sequences, or structural anomalies that the system fails to properly interpret or reject, thereby allowing malicious content to pass through security controls that should have blocked it.
From an operational perspective, this vulnerability presents a severe risk to organizations that depend on Cisco Firepower solutions for network protection, as it allows unauthenticated remote attackers to bypass critical security controls without requiring any credentials or privileged access. The implications extend beyond simple content filtering, as successful exploitation could enable attackers to deliver malware, establish command and control communications, or access protected internal systems that would normally be blocked by the security infrastructure. This vulnerability effectively neutralizes the protective measures that organizations have invested in implementing, potentially allowing attackers to establish persistent access or conduct advanced persistent threat activities against the network perimeter.
The security impact of CVE-2019-1982 aligns with CWE-20, which describes improper input validation, and can be mapped to ATT&CK technique T1071.004 for application layer protocol: DNS, demonstrating how this vulnerability could enable attackers to bypass network controls and establish communication patterns that would otherwise be blocked. Organizations should implement immediate mitigations including applying the latest security patches from Cisco, implementing additional network segmentation measures, and monitoring for suspicious traffic patterns that may indicate exploitation attempts. Network administrators should also consider implementing supplementary security controls such as deep packet inspection rules, additional header validation, and enhanced logging to detect potential exploitation attempts, while also conducting thorough vulnerability assessments to identify any potential unauthorized access that may have occurred during the window of vulnerability exposure.