CVE-2018-8965 in zzcms
Summary
by MITRE
An issue was discovered in zzcms 8.2. user/ppsave.php allows remote attackers to delete arbitrary files via directory traversal sequences in the oldimg parameter in an action=modify request. This can be leveraged for database access by deleting install.lock.
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Analysis
by VulDB Data Team • 01/16/2020
The vulnerability identified as CVE-2018-8965 affects zzcms version 8.2 and represents a critical directory traversal flaw in the user/ppsave.php component. This vulnerability arises from insufficient input validation and sanitization mechanisms that fail to properly restrict user-supplied data before processing file operations. The flaw specifically manifests when the application processes requests with the action=modify parameter and the oldimg parameter containing directory traversal sequences such as ../ or ..\.
The technical implementation of this vulnerability enables remote attackers to manipulate file paths through crafted input in the oldimg parameter. When the application receives such input, it does not adequately validate or sanitize the directory traversal sequences, allowing malicious actors to navigate outside the intended directory structure. This weakness directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as directory traversal or path traversal attacks. The vulnerability's exploitation potential extends beyond simple file deletion to include critical system compromise through database access manipulation.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with the capability to delete arbitrary files on the target system. The specific mention that this vulnerability can be leveraged for database access by deleting install.lock demonstrates the potential for escalation to full system compromise. The install.lock file typically serves as a marker indicating that the application has been properly installed and configured, and its deletion could allow attackers to reinstall the application or access underlying database structures. This represents a significant threat to system integrity and data confidentiality, as it provides an entry point for attackers to manipulate core application components.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1078.004 for Valid Accounts, as attackers could potentially use this flaw to execute commands or escalate privileges. The remote nature of the vulnerability means that attackers do not require physical access or local system credentials to exploit this flaw. The lack of proper input validation creates a persistent risk that can be exploited by anyone with network access to the vulnerable application, making it particularly dangerous in publicly accessible environments.
The recommended mitigations for this vulnerability include immediate implementation of strict input validation and sanitization for all user-supplied data, particularly parameters that influence file operations. The application should implement a whitelist approach for file paths, rejecting any input containing directory traversal sequences or special characters. Additionally, the system should enforce proper access controls and privilege separation to ensure that file operations cannot traverse beyond designated directories. Regular security auditing and code review practices should be implemented to identify similar vulnerabilities in other components of the application. The fix should also include logging and monitoring mechanisms to detect and alert on suspicious file access patterns. Organizations should also consider implementing web application firewalls and network segmentation to limit the potential impact of such vulnerabilities in production environments.