CVE-2021-36701 in htmly
Summary
by MITRE • 08/03/2021
In htmly version 2.8.1, is vulnerable to an Arbitrary File Deletion on the local host when delete backup files. The vulnerability may allow a remote attacker to delete arbitrary know files on the host.
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Analysis
by VulDB Data Team • 08/07/2021
The vulnerability identified as CVE-2021-36701 affects htmly version 2.8.1 and represents a critical arbitrary file deletion flaw that can be exploited by remote attackers to remove arbitrary files on the host system. This vulnerability specifically manifests during the backup file deletion process, where insufficient input validation and improper access controls allow malicious actors to manipulate the system into deleting files that should remain protected. The flaw stems from inadequate sanitization of user-supplied parameters that are used to determine which backup files should be removed from the system.
The technical implementation of this vulnerability resides in the backup management functionality of htmly, where the application fails to properly validate or sanitize file paths and names provided during the deletion operation. When an attacker can influence the deletion process through remote input, they can craft malicious requests that target specific files on the host system. This represents a classic path traversal vulnerability that has been categorized under CWE-22 - Improper Limitation of a Pathname to a Restricted Directory. The vulnerability allows for arbitrary file deletion because the application does not properly enforce file system access controls or validate that the requested files fall within the expected backup directory scope.
From an operational perspective, this vulnerability presents a severe risk to systems running htmly 2.8.1 as it enables remote code execution capabilities through file deletion attacks. An attacker could potentially delete critical system files, configuration files, or backup archives that would compromise system integrity and availability. The impact extends beyond simple file removal as it can lead to complete system compromise, data loss, and service disruption. This vulnerability aligns with ATT&CK technique T1070.004 - File Deletion, which describes methods attackers use to remove files and evidence from compromised systems. The remote exploitability means that attackers do not need physical access to the system and can leverage this vulnerability from any network location.
The mitigation strategy for CVE-2021-36701 requires immediate patching of the htmly application to version 2.8.2 or later, which contains the necessary fixes for input validation and access control enforcement. Organizations should implement network segmentation to limit access to the affected system and restrict the backup functionality to trusted administrative users only. Additionally, implementing proper input validation measures, including whitelisting of acceptable file paths and names, can prevent malicious manipulation of the deletion process. Regular security audits should verify that backup and file management functions properly enforce access controls and do not allow arbitrary file system manipulation. System monitoring should be enhanced to detect unusual file deletion patterns that may indicate exploitation attempts, and comprehensive backup strategies should be maintained to ensure recovery capabilities in case of successful attacks. The vulnerability demonstrates the critical importance of proper input validation and access control implementation in web applications to prevent remote attackers from manipulating system functions that could result in complete system compromise.