CVE-2020-13484 : Exploit Details and Defense Strategies

Bitrix24 through 20.0.975 allows SSRF via an intranet IP address in the services/main/ajax.php?action=attachUrlPreview url parameter, if the destination URL hosts an HTML document containing '<meta name="og:image" content="' followed by an intranet URL.

Understanding CVE-2020-13484

Bitrix24 through version 20.0.975 is vulnerable to SSRF due to improper handling of intranet IP addresses in specific URL parameters.

What is CVE-2020-13484?

This CVE describes a Server-Side Request Forgery (SSRF) vulnerability in Bitrix24 versions up to 20.0.975, allowing attackers to manipulate intranet IP addresses through a specific URL parameter.

The Impact of CVE-2020-13484

Attackers can exploit this vulnerability to bypass security controls and access sensitive information within the intranet environment.
SSRF can lead to unauthorized access to internal systems and potentially facilitate further attacks.

Technical Details of CVE-2020-13484

Bitrix24's vulnerability to SSRF can be further understood through the following technical details:

Vulnerability Description

The SSRF vulnerability arises from the mishandling of intranet IP addresses in the 'attachUrlPreview' URL parameter, specifically when the destination URL contains certain HTML elements.

Affected Systems and Versions

Product: Bitrix24
Vendor: N/A
Versions Affected: Up to 20.0.975

Exploitation Mechanism

Attackers can exploit this vulnerability by inserting an intranet IP address in the URL parameter 'attachUrlPreview' when the destination URL contains specific HTML content.

Mitigation and Prevention

To address CVE-2020-13484 and enhance security measures, consider the following mitigation strategies:

Immediate Steps to Take

Implement input validation to restrict URL parameters from accepting intranet IP addresses.
Regularly monitor and analyze network traffic for any suspicious SSRF attempts.

Long-Term Security Practices

Conduct regular security assessments and penetration testing to identify and remediate SSRF vulnerabilities.
Educate developers and administrators on secure coding practices to prevent SSRF and other similar attacks.

Patching and Updates

Apply patches and updates provided by Bitrix24 to fix the SSRF vulnerability and enhance overall system security.