CVE-2019-6739 in AntiMalware
Summary
by MITRE
This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Malwarebytes Antimalware 3.6.1.2711. User interaction is required to exploit this vulnerability in that the target must visit a malicious web page. There is an issue with the way the product handles URIs within certain schemes. The product does not warn the user that a dangerous navigation is about to take place. Because special characters in the URI are not sanitized, this could lead to the execution of arbitrary commands. An attacker can leverage this vulnerability to execute code in the context of the current user at medium integrity. Was ZDI-CAN-7162.
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Analysis
by VulDB Data Team • 09/26/2023
The vulnerability identified as CVE-2019-6739 represents a critical remote code execution flaw within Malwarebytes Antimalware version 3.6.1.2711 that demonstrates the dangerous consequences of inadequate input validation in security software. This weakness falls under the category of improper input validation as classified by CWE-20, specifically manifesting in the product's failure to properly sanitize URI schemes and their associated special characters. The vulnerability is particularly concerning because it operates through a web-based attack vector, requiring only user interaction via visiting a malicious webpage, making it highly exploitable in real-world scenarios where social engineering can be employed to lure victims into triggering the exploit.
The technical implementation of this vulnerability stems from the application's handling of Uniform Resource Identifiers within specific URI schemes without proper sanitization of special characters that could be interpreted as command sequences. When a user navigates to a maliciously crafted webpage containing a specially constructed URI, the application fails to implement adequate warning mechanisms or input validation checks. This oversight allows attackers to craft URLs that contain encoded or special characters which, when processed by the vulnerable application, can be interpreted as executable commands rather than simple navigation instructions. The lack of user warnings creates a false sense of security, as users are not informed about the potentially dangerous navigation that will occur, making the attack more successful and harder to detect.
The operational impact of this vulnerability extends beyond simple code execution, as it allows an attacker to operate with the integrity level of the currently logged-in user, which typically represents a medium integrity context. This means that while the attacker cannot escalate privileges beyond the user's current access level, they can still perform actions that are limited by the user's permissions, including accessing sensitive files, modifying system configurations, or installing additional malicious software. The vulnerability's exploitation requires minimal technical skill from the attacker, as it relies on standard web-based attack methods combined with the application's failure to validate input properly, making it particularly dangerous for organizations where user interaction with potentially malicious websites is common.
Mitigation strategies for CVE-2019-6739 should focus on immediate patching of the affected Malwarebytes Antimalware version, as this represents the most effective solution to prevent exploitation. Organizations should also implement network-level protections such as web filtering solutions that can detect and block malicious URI schemes before they reach vulnerable endpoints. Additionally, user education programs should emphasize the importance of verifying website legitimacy before visiting unfamiliar sites, particularly when the sites contain unusual URL structures or redirect to unexpected destinations. Security controls should include monitoring for unusual command execution patterns and implementing strict input validation measures for all URI handling within security applications. The vulnerability's classification under ATT&CK technique T1059.007 (Command and Scripting Interpreter: PowerShell) highlights the need for monitoring PowerShell execution patterns that might indicate exploitation attempts, while the broader ATT&CK framework classification under T1203 (Exploitation for Client Execution) underscores the importance of defending against web-based exploitation vectors that leverage client-side vulnerabilities.