CVE-2019-18949 in SnowHaze
Summary
by MITRE
SnowHaze before 2.6.6 is sometimes too late to honor a per-site JavaScript blocking setting, which leads to unintended JavaScript execution via a chain of webpage redirections targeted to the user's browser configuration.
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Analysis
by VulDB Data Team • 02/20/2024
The vulnerability identified as CVE-2019-18949 affects SnowHaze versions prior to 2.6.6, representing a critical flaw in the browser's content filtering and security mechanisms. This issue stems from a timing discrepancy in how the security system processes JavaScript blocking settings, creating a window where malicious scripts can execute despite user configurations intended to prevent such activity. The flaw manifests through a sophisticated chain of webpage redirections that exploit the temporal gap between when per-site JavaScript blocking settings are configured and when they are effectively enforced, allowing attackers to bypass intended security controls.
The technical implementation of this vulnerability involves a race condition or timing flaw within SnowHaze's security enforcement framework. When users configure JavaScript blocking for specific websites, the system should immediately enforce these restrictions. However, the flaw allows malicious actors to craft redirection chains that exploit the delay between configuration application and enforcement, potentially enabling JavaScript execution during the transitional period. This creates a scenario where legitimate security controls become ineffective against targeted attacks that leverage browser configuration timing.
From an operational perspective, this vulnerability poses significant risks to user security and privacy, particularly in environments where users rely on SnowHaze for content filtering and malware protection. The attack vector involves carefully constructed webpage redirection sequences that can be delivered through various means including phishing emails, compromised websites, or malicious advertisements. The impact extends beyond simple script execution to potentially enable more sophisticated attacks such as credential theft, malware delivery, or data exfiltration, as the bypassed JavaScript restrictions may allow attackers to inject malicious code or manipulate browser behavior.
The vulnerability aligns with CWE-367 Time-of-Check to Time-of-Use (TOCTOU) flaws, where the system's state changes between the moment when a security check is performed and when the action is executed. This weakness enables attackers to manipulate the system state during the interim period, effectively circumventing intended security measures. The issue also relates to ATT&CK technique T1217, which involves exploiting browser security features through manipulation of browser configurations or timing-based attacks. Organizations using SnowHaze versions before 2.6.6 face potential exposure to these sophisticated attacks that can undermine the browser's intended security posture.
Mitigation strategies should prioritize immediate upgrade to SnowHaze 2.6.6 or later versions where the timing issue has been resolved. Security administrators should also implement additional monitoring for unusual redirection patterns and JavaScript execution behaviors that might indicate exploitation attempts. Network-level controls such as web application firewalls and content filtering systems can provide additional protection layers while the software upgrade is being deployed. Regular security assessments should verify that JavaScript blocking configurations are properly enforced and that no temporal gaps exist in the security enforcement mechanisms. Organizations should also consider implementing user education programs to recognize potential phishing attempts that might leverage this vulnerability through malicious redirection chains.