CVE-2019-3635 in Web Gateway
Summary
by MITRE
Exfiltration of Data in McAfee Web Gateway (MWG) 7.8.2.x prior to 7.8.2.12 allows attackers to obtain sensitive data via crafting a complex webpage that will trigger the Web Gateway to block the user accessing an iframe.
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Analysis
by VulDB Data Team • 11/25/2023
The vulnerability identified as CVE-2019-3635 represents a significant security flaw in McAfee Web Gateway version 7.8.2.x prior to 7.8.2.12, specifically impacting the web filtering and content inspection capabilities of this enterprise security solution. This vulnerability enables attackers to perform data exfiltration by exploiting a flaw in how the Web Gateway handles certain webpage constructs, particularly those involving iframe elements that trigger blocking mechanisms. The issue stems from improper handling of complex web pages that contain maliciously crafted iframe references, allowing unauthorized data access through the gateway's filtering processes.
This technical flaw operates through a sophisticated exploitation mechanism that leverages the Web Gateway's response to blocked content and iframe processing. When users attempt to access webpages containing specifically crafted iframe elements, the gateway's blocking logic inadvertently creates conditions that permit data extraction from internal networks or sensitive systems. The vulnerability manifests when the system processes these complex web constructs, causing it to expose information that should remain protected within the organization's security boundaries. This behavior constitutes a bypass of the intended security controls that the Web Gateway is designed to enforce, creating an unexpected data leakage pathway.
The operational impact of CVE-2019-3635 extends beyond simple data exposure, as it represents a critical compromise of network security controls that organizations rely upon for protecting sensitive information. Attackers can leverage this vulnerability to access confidential data, internal network resources, and potentially escalate privileges within the affected environment. The flaw particularly affects organizations using McAfee Web Gateway as their primary web filtering solution, where the security controls are expected to prevent unauthorized access to sensitive content and protect against data leakage. This vulnerability undermines the fundamental security posture of affected organizations by creating a backdoor through which attackers can extract valuable information without triggering standard security alerts.
Organizations should implement immediate mitigations including updating to McAfee Web Gateway version 7.8.2.12 or later, which contains the necessary patches to address this vulnerability. Network administrators should also consider implementing additional monitoring controls to detect anomalous traffic patterns that might indicate exploitation attempts, particularly around iframe processing and content blocking events. The vulnerability aligns with CWE-200, which addresses information exposure, and represents a specific implementation flaw in the Web Gateway's content inspection and filtering mechanisms. From an ATT&CK framework perspective, this vulnerability maps to techniques involving data exfiltration and privilege escalation through exploitation of application-level security controls, emphasizing the need for comprehensive network security monitoring and regular patch management procedures to prevent unauthorized access to sensitive organizational data.