CVE-2020-25878 in BlackCat
Summary
by MITRE • 07/10/2021
A stored cross site scripting (XSS) vulnerability in the 'Admin-Tools' feature of BlackCat CMS 1.3.6 allows authenticated attackers to execute arbitrary web scripts or HTML via crafted payloads entered into the 'Output Filters' and 'Droplets' modules.
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Analysis
by VulDB Data Team • 07/15/2021
The vulnerability identified as CVE-2020-25878 represents a critical stored cross site scripting flaw within the BlackCat CMS 1.3.6 administrative interface. This security weakness specifically affects the Admin-Tools feature, creating a persistent threat vector that allows authenticated attackers to inject malicious scripts into the system's output filters and droplets modules. The vulnerability stems from insufficient input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before rendering it within the web application's interface. Attackers exploiting this flaw can craft malicious payloads that persist in the system's database and execute automatically whenever affected pages are loaded by other users with appropriate privileges. The stored nature of this vulnerability means that the malicious code remains embedded within the application's data stores, making it particularly dangerous as it can affect multiple users over extended periods without requiring repeated exploitation attempts.
The technical implementation of this vulnerability aligns with CWE-79 which categorizes cross site scripting flaws as weaknesses in input validation and output encoding. The attack surface is specifically centered around the administrative functionality of the CMS where legitimate users with appropriate permissions can inadvertently trigger the execution of malicious scripts through crafted inputs in the Output Filters and Droplets modules. These modules serve as entry points where user-generated content is processed and rendered, creating opportunities for attackers to inject malicious JavaScript code or HTML content that gets stored and subsequently executed in the context of other users' browsers. The vulnerability demonstrates a classic case of insufficient sanitization of user inputs, where the application fails to properly escape or validate data before it is stored and later displayed to authenticated users. This flaw operates under the principle that all user-supplied data should be treated as untrusted and properly encoded before being incorporated into dynamic web content.
The operational impact of CVE-2020-25878 extends beyond simple script execution to potentially enable more sophisticated attacks including session hijacking, credential theft, and privilege escalation within the CMS environment. An attacker who successfully exploits this vulnerability can leverage the stored XSS to capture authentication cookies, redirect users to malicious domains, or inject additional malicious payloads that could compromise the entire administrative interface. The authenticated nature of the attack means that attackers need only obtain legitimate user credentials to exploit this vulnerability, making it particularly dangerous in environments where administrative privileges are not adequately protected. The persistent nature of stored XSS allows for long-term compromise of the system, as the malicious code continues to execute each time affected pages are accessed by other users. This vulnerability can also serve as a stepping stone for more comprehensive attacks, potentially enabling attackers to escalate privileges or access sensitive administrative functions that are protected by standard authentication mechanisms.
Mitigation strategies for CVE-2020-25878 should focus on implementing comprehensive input validation and output encoding mechanisms throughout the application's administrative modules. The most effective immediate solution involves updating to a patched version of BlackCat CMS that addresses the specific input sanitization issues in the Output Filters and Droplets modules. Organizations should implement strict content sanitization policies that strip or encode potentially dangerous characters and tags from user inputs before storage. The implementation of a robust Content Security Policy (CSP) can provide additional protection by restricting the sources from which scripts can be loaded and executed within the application context. Regular security audits of administrative interfaces should be conducted to identify similar input validation weaknesses that could lead to similar vulnerabilities. Additionally, implementing multi-factor authentication for administrative accounts and limiting administrative privileges to only essential personnel can reduce the potential impact of successful exploitation. The vulnerability highlights the importance of defense-in-depth strategies where multiple layers of security controls work together to prevent or limit the impact of XSS attacks, as outlined in the ATT&CK framework's approach to web application vulnerabilities and the specific techniques related to client-side code injection.