CVE-2018-19748 in SDcms
Summary
by MITRE
app/plug/attachment/controller/admincontroller.php in SDCMS 1.6 allows reading arbitrary files via a /?m=plug&c=admin&a=index&p=attachment&root= directory traversal. The value of the root parameter must be base64 encoded (note that base64 encoding, instead of URL encoding, is very rare in a directory traversal attack vector).
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Analysis
by VulDB Data Team • 04/16/2020
The vulnerability identified as CVE-2018-19748 exists within the SDCMS 1.6 content management system, specifically in the file app/plug/attachment/controller/admincontroller.php. This flaw represents a critical directory traversal vulnerability that enables unauthorized users to access arbitrary files on the server. The vulnerability manifests through a carefully crafted request parameter where the root parameter is base64 encoded rather than the more common URL encoding approach. This unusual encoding method makes the attack vector more sophisticated and potentially harder to detect through standard security monitoring systems. The vulnerability occurs when the application processes the directory traversal request without proper input validation or sanitization, allowing an attacker to manipulate the file system access path. The attack requires an attacker to construct a malicious request with the specific URL pattern ?m=plug&c=admin&a=index&p=attachment&root= which triggers the vulnerable code path. The base64 encoding of the root parameter is particularly noteworthy as it deviates from typical directory traversal exploitation patterns where URL encoding is the standard approach, suggesting either a novel attack technique or an implementation error in the CMS's parameter handling.
The technical exploitation of this vulnerability stems from insufficient input validation and sanitization within the administrative attachment controller. When the application receives the base64 encoded root parameter, it fails to properly validate or sanitize the input before using it in file system operations. This allows an attacker to inject directory traversal sequences such as ../ or ..\ that can navigate outside the intended directory structure. The base64 encoding serves as an obfuscation technique that bypasses some automated security filters that might be designed to detect traditional URL encoded directory traversal attempts. The vulnerability operates at the application layer and requires minimal privileges to exploit, as it leverages existing administrative functionality within the CMS. The attack can potentially expose sensitive files including configuration files, database credentials, application source code, and other privileged information that should remain inaccessible to unauthorized users.
The operational impact of this vulnerability is severe and multifaceted for organizations running SDCMS 1.6. An attacker who successfully exploits this vulnerability can gain access to sensitive system information that could lead to further compromise of the entire web application infrastructure. The exposure of configuration files might reveal database connection strings, API keys, and other credentials that could be used for lateral movement within the network. Additionally, the ability to read arbitrary files could expose the application source code, potentially revealing additional vulnerabilities or business logic that could be exploited. The vulnerability also poses a risk to data confidentiality as attackers can access files that contain sensitive user information, business data, or intellectual property. Organizations may face regulatory compliance violations if sensitive data is exposed, and the reputation damage from such security incidents can be significant. The attack vector's use of base64 encoding makes it more difficult to detect through standard web application firewalls and intrusion detection systems that may not be configured to handle this specific encoding approach.
Mitigation strategies for this vulnerability should focus on immediate patching of the SDCMS 1.6 application to the latest version that addresses this directory traversal flaw. Organizations should also implement comprehensive input validation and sanitization measures within their web applications to prevent similar vulnerabilities from occurring. The application should validate all file system access requests and ensure that paths are properly restricted to intended directories without allowing traversal sequences. Security monitoring should be enhanced to detect unusual encoding patterns such as base64 encoding in directory traversal attempts. Organizations should also consider implementing web application firewalls with signature-based detection for known directory traversal attack patterns. Access controls should be reviewed and strengthened to ensure that administrative functions are properly protected and that only authorized personnel can access sensitive administrative interfaces. Regular security assessments and penetration testing should be conducted to identify and remediate similar vulnerabilities in the application code. The vulnerability aligns with CWE-22 Directory Traversal and follows ATT&CK technique T1083 File and Directory Discovery, highlighting the need for proper input validation and access control measures to prevent unauthorized file system access.