CVE-2018-14729 in Discuz!
Summary
by MITRE
The database backup feature in upload/source/admincp/admincp_db.php in Discuz! 2.5 and 3.4 allows remote attackers to execute arbitrary PHP code.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 04/05/2020
The vulnerability identified as CVE-2018-14729 represents a critical remote code execution flaw within the Discuz versions 2.5 and 3.4. The flaw stems from inadequate input validation and sanitization mechanisms that fail to properly restrict user-supplied data when processing backup operations. Attackers can exploit this weakness by crafting malicious input parameters that bypass normal security checks, ultimately allowing them to inject and execute arbitrary PHP code on the affected server. The vulnerability is particularly dangerous because it resides within the administrative control panel, providing attackers with elevated privileges and direct access to the underlying system. This issue falls under the CWE-94 category of "Improper Control of Generation of Code" and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" when considering the broader attack surface. The vulnerability's impact extends beyond simple code execution, as it can enable attackers to establish persistent backdoors, exfiltrate sensitive data, or compromise the entire web server infrastructure. The flaw essentially creates a pathway for attackers to bypass authentication mechanisms and directly manipulate the application's behavior through malicious payload injection.
The technical implementation of this vulnerability occurs through improper handling of file upload and backup operations within the Discuz! administrative interface. When administrators or authenticated users perform database backup operations, the system processes user-provided parameters without sufficient validation to prevent code injection attacks. The backup feature likely accepts parameters that control file naming, storage locations, or execution contexts, which are then processed without proper sanitization. This lack of input filtering creates an environment where attackers can inject PHP code directly into backup operations, which subsequently gets executed when the backup process runs. The vulnerability is particularly insidious because it leverages legitimate administrative functions to achieve malicious code execution, making it difficult to detect through traditional security monitoring. The flaw demonstrates poor secure coding practices and highlights the importance of input validation in web applications. Attackers can exploit this by manipulating backup-related parameters to include malicious PHP code that gets executed during the backup process, effectively providing a remote code execution vector that bypasses normal application security controls.
The operational impact of CVE-2018-14729 is severe and multifaceted for organizations running affected Discuz! versions. Successful exploitation allows attackers to gain full control over the affected web server, potentially leading to complete system compromise and data breaches. The vulnerability enables attackers to execute arbitrary commands with the privileges of the web server process, which typically has write access to the application directory and database connections. This access level permits attackers to modify or delete forum content, steal user credentials, access sensitive database information, and establish persistent access through backdoor installations. The implications extend to data integrity and confidentiality, as attackers can manipulate forum data, user accounts, and system configurations. Organizations may also face regulatory compliance violations and reputational damage if sensitive information is compromised. The vulnerability's presence in widely deployed forum software means that numerous websites and organizations could be at risk, particularly those that have not updated to patched versions. The attack vector requires only a valid administrative session or the ability to perform backup operations, making it accessible to attackers who have gained any level of administrative access to the forum.
Mitigation strategies for CVE-2018-14729 focus primarily on immediate remediation and long-term security hardening measures. The most effective solution involves upgrading to patched versions of Discuz! 2.5 and 3.4, as vendors have released security updates addressing this specific vulnerability. Organizations should implement immediate network segmentation and access controls to limit administrative access to the affected system. Additional defensive measures include disabling unnecessary administrative features, implementing web application firewalls to monitor and filter suspicious requests, and conducting thorough code reviews to identify similar input validation weaknesses. Security monitoring should include detection of unusual backup operations and file modifications. The vulnerability highlights the importance of principle of least privilege implementation, where administrative functions are restricted to only necessary personnel with proper authentication. Organizations should also implement regular security assessments and penetration testing to identify similar vulnerabilities in their web applications. The remediation process must include thorough testing of patched versions to ensure that legitimate functionality remains intact while eliminating the security risk. Furthermore, implementing automated patch management systems can prevent similar vulnerabilities from remaining unaddressed in the future. Security teams should also establish incident response procedures specifically designed to handle remote code execution vulnerabilities, ensuring rapid detection and containment of potential exploitation attempts.