CVE-2023-1719 in Bitrix24
Summary
by MITRE • 11/01/2023
Global variable extraction in bitrix/modules/main/tools.php in Bitrix24 22.0.300 allows unauthenticated remote attackers to (1) enumerate attachments on the server and (2) execute arbitrary JavaScript code in the victim's browser, and possibly execute arbitrary PHP code on the server if the victim has administrator privilege, via overwriting uninitialised variables.
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Analysis
by VulDB Data Team • 11/29/2023
The vulnerability identified as CVE-2023-1719 represents a critical security flaw in Bitrix24 version 22.0.300 within the bitrix/modules/main/tools.php file. This issue stems from improper handling of global variable extraction that creates multiple attack vectors for unauthenticated remote adversaries. The vulnerability operates through a dangerous pattern where attackers can manipulate variable initialization processes to achieve unauthorized access and code execution across multiple system layers.
The technical implementation of this vulnerability involves a specific flaw in how the tools.php file manages global variable assignments and extraction processes. When the application processes certain input parameters, it fails to properly initialize variables before extracting them from global scope. This creates an environment where attackers can inject malicious data into uninitialized variables, effectively bypassing normal input validation mechanisms. The flaw specifically affects the way the system handles variable overwrites during processing, allowing attackers to manipulate the execution flow of the application.
From an operational perspective, this vulnerability presents attackers with three distinct attack paths that escalate in severity. The first vector enables attachment enumeration, allowing threat actors to discover and map file structures on the target server without authentication. The second vector provides arbitrary JavaScript execution in victim browsers, creating potential for cross-site scripting attacks and user session hijacking. The third and most severe vector allows for arbitrary PHP code execution on the server when victims possess administrative privileges, effectively providing complete system compromise capabilities. This multi-layered attack surface significantly increases the potential impact of exploitation.
The vulnerability aligns with CWE-1280, which specifically addresses the issue of uninitialized variables in global scope, and represents a classic example of improper input validation combined with variable manipulation. From an attack framework perspective, this vulnerability maps to multiple ATT&CK techniques including T1059 for command and scripting interpreter usage, T1566 for credential harvesting through social engineering, and T1190 for exploitation of remote services. The attack chain typically begins with reconnaissance through attachment enumeration, followed by payload delivery via JavaScript injection, and culminates in privilege escalation when administrative accounts are compromised.
Mitigation strategies must address the fundamental variable initialization issue within the tools.php file and implement comprehensive input validation controls. Organizations should immediately apply the vendor-provided patch or update to a secure version of Bitrix24 that properly initializes all variables before extraction. Additional defensive measures include implementing web application firewalls to monitor for suspicious parameter patterns, conducting thorough code reviews to identify similar uninitialized variable patterns, and establishing strict input sanitization protocols. Network segmentation and privilege separation should be enforced to limit potential damage from successful exploitation, particularly ensuring that administrative accounts operate with least privilege principles to prevent full system compromise.