CVE-2018-20128 in UsualToolCMS
Summary
by MITRE
An issue was discovered in UsualToolCMS v8.0. cmsadmin\a_sqlback.php allows remote attackers to delete arbitrary files via a backname[] directory-traversal pathname followed by a crafted substring.
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Analysis
by VulDB Data Team • 04/20/2020
This vulnerability exists within UsualToolCMS version 8.0 where the cmsadmin_sqlback.php component fails to properly validate user-supplied input parameters. The flaw specifically manifests when processing the backname[] parameter which is used to define backup file paths. Attackers can exploit this weakness by crafting malicious directory traversal sequences that bypass normal path validation mechanisms, allowing them to target arbitrary files on the server filesystem. The vulnerability stems from insufficient input sanitization and improper path resolution logic within the backup management functionality.
The technical implementation of this vulnerability follows a classic directory traversal attack pattern where malicious input containing sequences like ../ or ..\ are not properly filtered or escaped before being used in file operations. When the application processes these crafted inputs, it performs file deletion operations on paths that should be restricted, enabling attackers to remove files outside of intended backup directories. This represents a critical authorization bypass vulnerability that allows remote attackers to execute arbitrary file deletion commands without proper authentication or access controls.
From an operational perspective, this vulnerability poses significant risks to system integrity and data availability. Remote attackers can leverage this flaw to delete critical application files, configuration data, or even system binaries that could lead to complete application compromise or service disruption. The impact extends beyond simple data loss as attackers could potentially remove security-related components or logs that would aid in forensic analysis. This vulnerability also aligns with attack patterns documented in the mitre ATT&CK framework under T1070 (Indicator Removal on Host) and T1485 (Data Destruction) tactics, as it enables unauthorized file removal operations that could be part of broader destructive attack campaigns.
The vulnerability can be mitigated through multiple defensive measures including implementing proper input validation that filters or rejects directory traversal sequences, enforcing strict path validation that ensures all file operations occur within designated safe directories, and applying the principle of least privilege to restrict file system access. Organizations should also consider implementing web application firewalls that can detect and block suspicious path traversal patterns, as well as regular security audits of file operations within web applications. Additionally, upgrading to patched versions of UsualToolCMS or implementing proper parameter sanitization in the affected cmsadmin_sqlback.php component would resolve this vulnerability. The weakness aligns with CWE-22 which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal attacks, making it a well-documented and commonly exploited vulnerability pattern in web applications.