CVE-2021-40285 in htmly
Summary
by MITRE • 08/26/2022
htmly v2.8.1 was discovered to contain an arbitrary file deletion vulnerability via the component \views\backup.html.php.
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Analysis
by VulDB Data Team • 10/02/2022
The vulnerability identified as CVE-2021-40285 affects htmly version 2.8.1 and represents a critical arbitrary file deletion flaw within the backup component of the application. This vulnerability exists in the views/backup.html.php file, which processes user input without proper validation or sanitization mechanisms. The flaw allows authenticated attackers with sufficient privileges to manipulate the backup functionality and delete arbitrary files from the server filesystem, potentially leading to complete system compromise or data destruction.
This vulnerability falls under CWE-22 which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal attacks. The issue stems from inadequate input validation where user-supplied parameters are directly processed without proper authorization checks or path normalization. Attackers can exploit this weakness by crafting malicious requests that target specific file paths, bypassing normal access controls and executing unauthorized file deletion operations. The vulnerability demonstrates a classic lack of proper access control implementation in web applications, where administrative functions are not properly secured against unauthorized access.
The operational impact of CVE-2021-40285 extends beyond simple data loss, as it can facilitate more sophisticated attack vectors including complete system compromise. An attacker who successfully exploits this vulnerability can delete critical system files, application binaries, configuration files, or database files, potentially leading to application unavailability or complete system shutdown. The vulnerability also enables attackers to target backup files themselves, potentially preventing legitimate recovery operations and increasing the impact of data loss incidents. This type of vulnerability can be particularly damaging in production environments where automated backup systems are critical for business continuity.
The threat landscape for this vulnerability aligns with ATT&CK technique T1485 which covers "Data Destruction" and T1566 which addresses "Phishing" as attackers may use this vulnerability to target systems after initial compromise. Organizations should implement immediate mitigations including applying the vendor-provided patch, implementing proper input validation and sanitization, restricting file system permissions for backup components, and monitoring for suspicious file deletion activities. Additionally, network segmentation and intrusion detection systems should be configured to alert on unusual backup file operations. The vulnerability underscores the importance of proper access control mechanisms and input validation in web applications, as highlighted in NIST SP 800-160 and OWASP Top Ten categories related to injection flaws and access control issues.