CVE-2023-1715 in Bitrix24
Summary
by MITRE • 11/01/2023
A logic error when using mb_strpos() to check for potential XSS payload in Bitrix24 22.0.300 allows attackers to bypass XSS sanitisation via placing HTML tags at the begining of the payload.
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Analysis
by VulDB Data Team • 11/29/2023
The vulnerability identified as CVE-2023-1715 represents a critical logic flaw in the Bitrix24 22.0.300 web application that affects cross-site scripting sanitization mechanisms. This issue specifically manifests within the mb_strpos() function implementation used for detecting potential XSS payloads, creating a security gap that adversaries can exploit to circumvent intended protection measures.
The technical flaw stems from improper handling of HTML tag placement within malicious payloads during the sanitization process. When attackers position HTML tags at the beginning of their XSS payloads, the mb_strpos() function fails to properly identify these threats due to its limited logic in evaluating string positions. This function typically searches for specific substrings within strings, but in this case, the positioning of HTML tags at the payload's beginning allows the sanitization routine to overlook the malicious content entirely. The vulnerability operates at the application layer and specifically targets the input validation and sanitization components that are crucial for protecting against XSS attacks.
The operational impact of this vulnerability is significant as it enables attackers to bypass security controls that are designed to prevent cross-site scripting attacks. An attacker can craft malicious payloads with HTML tags positioned at the beginning of their input, which then passes through the flawed sanitization process undetected. This bypass capability allows for potential session hijacking, data theft, and unauthorized access to user accounts. The vulnerability affects the core security mechanisms of Bitrix24, which is a widely used business management platform, potentially exposing thousands of organizations to persistent security threats.
This vulnerability aligns with CWE-79 which addresses Cross-Site Scripting in software applications, and specifically relates to improper input validation and sanitization techniques. The flaw also corresponds to ATT&CK technique T1203 which involves exploitation of web application vulnerabilities for code execution and privilege escalation. Organizations using Bitrix24 22.0.300 should immediately implement mitigations including updating to patched versions, implementing additional input validation layers, and conducting thorough security assessments of their web applications. The recommended approach involves strengthening the mb_strpos() implementation to properly handle edge cases involving HTML tag placement and implementing comprehensive payload analysis that considers all potential tag positions rather than relying on single-position detection methods. Security teams should also consider implementing Web Application Firewalls and additional monitoring mechanisms to detect anomalous input patterns that might indicate exploitation attempts.