CVE-2020-18917 in DeDeCMS
Summary
by MITRE • 08/25/2021
The plus/search.php component in DedeCMS 5.7 SP2 allows remote attackers to execute arbitrary PHP code via the typename parameter because the contents of typename.inc are under an attacker's control.
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Analysis
by VulDB Data Team • 08/26/2021
The vulnerability CVE-2020-18917 represents a critical remote code execution flaw within DedeCMS version 5.7 SP2 that stems from improper input validation in the plus/search.php component. This weakness specifically manifests through the typename parameter which directly influences how the system processes user-supplied data, creating a pathway for attackers to inject and execute arbitrary PHP code on the affected server. The vulnerability is categorized under CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')" and aligns with ATT&CK technique T1190 "Exploit Public-Facing Application" as it targets a web application component accessible from external networks.
The technical implementation of this vulnerability exploits the insecure handling of the typename parameter by allowing attackers to manipulate the typename.inc file contents through direct input control. When a user submits a request containing malicious code within the typename parameter, the application fails to properly sanitize or validate this input before incorporating it into the execution flow. This flaw essentially permits an attacker to bypass normal access controls and execute arbitrary commands with the privileges of the web server process. The vulnerability's exploitation pathway demonstrates a classic code injection vulnerability where user-controllable input directly influences the execution context, making it particularly dangerous for web applications that process untrusted data without proper sanitization.
From an operational perspective, this vulnerability presents a severe risk to organizations using DedeCMS 5.7 SP2 as it provides attackers with complete system compromise capabilities. The remote execution nature means that attackers do not require local access or physical presence to exploit the vulnerability, making it particularly attractive for automated attack campaigns. Successful exploitation can lead to full system takeover, data exfiltration, persistent backdoor installation, and further lateral movement within the network. The impact extends beyond immediate code execution as attackers can leverage this access to establish persistent presence, modify website content, steal sensitive data, or use the compromised system as a launch point for attacking other systems within the organization's infrastructure.
Organizations should prioritize immediate mitigation through official patches provided by DedeCMS vendors, as the vulnerability has been widely documented and exploited in the wild. The recommended approach includes implementing proper input validation and sanitization measures, restricting file upload capabilities, and applying web application firewalls to detect and block malicious requests targeting this specific vulnerability. Additionally, organizations should conduct thorough security assessments of their web applications to identify similar injection vulnerabilities and implement defense-in-depth strategies such as least privilege access controls, regular security monitoring, and network segmentation to limit the potential impact of successful exploitation attempts.