CVE-2023-1718 in Bitrix24
Summary
by MITRE • 11/01/2023
Improper file stream access in /desktop_app/file.ajax.php?action=uploadfile in Bitrix24 22.0.300 allows unauthenticated remote attackers to cause denial-of-service via a crafted "tmp_url".
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Analysis
by VulDB Data Team • 11/29/2023
The vulnerability identified as CVE-2023-1718 affects Bitrix24 version 22.0.300 and resides within the desktop_app/file.ajax.php script where the uploadfile action is processed. This flaw represents a critical security weakness that permits unauthenticated remote attackers to exploit improper file stream access mechanisms. The vulnerability specifically manifests when processing a crafted tmp_url parameter, which allows attackers to manipulate the file upload functionality in ways that can disrupt normal service operations.
The technical implementation of this vulnerability stems from inadequate input validation and improper handling of file stream operations within the Bitrix24 desktop application framework. When the system processes the uploadfile action, it fails to properly sanitize or validate the tmp_url parameter, creating an opportunity for attackers to inject malicious file paths or manipulate the file handling process. This weakness falls under the category of improper input validation and can be classified as a CWE-20 weakness related to improper input sanitization. The vulnerability exists in the application layer where it processes user-supplied data without sufficient security controls to prevent malicious manipulation of file access streams.
From an operational impact perspective, this vulnerability enables remote attackers to cause denial-of-service conditions within the Bitrix24 environment. The crafted tmp_url parameter allows attackers to potentially disrupt legitimate file upload operations, causing system instability or complete service interruption. This type of attack can have cascading effects on business operations that depend on Bitrix24 for collaboration, document management, and workflow automation. The vulnerability affects the availability aspect of the CIA triad and can be particularly damaging in enterprise environments where continuous access to collaboration platforms is critical for business operations.
The exploitation of this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to denial-of-service attacks and privilege escalation through application vulnerabilities. Attackers can leverage this weakness to perform service disruption attacks without requiring authentication, making it particularly dangerous in environments where Bitrix24 is exposed to external networks. The attack surface is expanded by the fact that this vulnerability affects the desktop application component, which may be accessible from various network locations within enterprise environments.
Effective mitigation strategies for CVE-2023-1718 should include immediate patching of the Bitrix24 platform to the latest version that addresses this specific vulnerability. Organizations should implement network segmentation to limit access to the vulnerable desktop application components and apply proper input validation controls at the application level. Additionally, monitoring for suspicious file upload activities and implementing web application firewalls can help detect and prevent exploitation attempts. The implementation of principle of least privilege access controls for file upload functionality should also be enforced to minimize potential impact if exploitation occurs. Security teams should also consider implementing automated vulnerability scanning tools that can detect similar improper file stream access patterns within their infrastructure.