CVE-2017-14399 in BlackCat
Summary
by MITRE
In BlackCat CMS 1.2.2, unrestricted file upload is possible in backend\media\ajax_rename.php via the extension parameter, as demonstrated by changing the extension from .jpg to .php.
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Analysis
by VulDB Data Team • 11/15/2019
The vulnerability identified as CVE-2017-14399 represents a critical security flaw in BlackCat CMS version 1.2.2 that enables unauthorized file upload capabilities within the administrative backend. This issue specifically affects the backend\media\jax_rename.php component where user input is improperly validated, creating an opportunity for malicious actors to execute arbitrary code on the target system. The vulnerability stems from insufficient input sanitization mechanisms that fail to properly validate file extensions, allowing attackers to manipulate the extension parameter to upload malicious files with executable extensions.
The technical implementation of this vulnerability occurs through the jax_rename.php script which processes file renaming operations without adequate validation of file types or extensions. When an attacker supplies a malicious file extension such as .php instead of the expected .jpg, the system accepts the modification without proper security checks. This weakness aligns with CWE-434, which describes the improper restriction of file uploads, and represents a classic example of insecure file handling in web applications. The flaw demonstrates poor input validation practices where the application trusts user-supplied data without proper sanitization, creating a direct pathway for remote code execution.
From an operational perspective, this vulnerability poses significant risks to organizations utilizing BlackCat CMS 1.2.2 as it allows attackers to upload malicious files that can be executed within the web server context. Once a malicious PHP file is uploaded, an attacker can establish persistent access to the system, potentially leading to complete compromise of the web server and underlying infrastructure. The impact extends beyond immediate code execution to include potential data exfiltration, lateral movement within the network, and establishment of backdoor access points. This vulnerability can be exploited through various attack vectors including social engineering, automated scanning tools, or by leveraging compromised credentials that grant access to the administrative backend.
The exploitation of this vulnerability follows established patterns documented in the MITRE ATT&CK framework under techniques such as T1190 for exploit public-facing application and T1059 for command and scripting interpreter. Security professionals should implement immediate mitigations including input validation controls, file type restriction mechanisms, and proper access controls for administrative functions. Recommended defenses include implementing strict file extension validation, using random or secure naming conventions for uploaded files, restricting file upload capabilities to authorized users only, and deploying web application firewalls to monitor and block suspicious upload attempts. Additionally, organizations should conduct comprehensive security audits to identify similar vulnerabilities in other components and ensure proper patch management protocols are in place to address known security flaws in content management systems.