CVE-2018-9153 in Z-BlogPHP
Summary
by MITRE
The plugin upload component in Z-BlogPHP 1.5.1 allows remote attackers to execute arbitrary PHP code via the app_id parameter to zb_users/plugin/AppCentre/plugin_edit.php because of an unanchored regular expression, a different vulnerability than CVE-2018-8893. The component must be accessed directly by an administrator, or through CSRF.
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Analysis
by VulDB Data Team • 01/25/2020
The vulnerability identified as CVE-2018-9153 affects Z-BlogPHP version 1.5.1 and resides within the plugin upload component of the application. This represents a critical security flaw that enables remote code execution through a specifically crafted parameter named app_id within the zb_users/plugin/AppCentre/plugin_edit.php file. The vulnerability stems from an improperly configured regular expression that lacks proper anchoring, creating a pathway for malicious actors to inject and execute arbitrary PHP code on the target system. Unlike similar vulnerabilities such as CVE-2018-8893, this issue manifests through a distinct code path involving the plugin management functionality. The attack vector requires administrative access to the application, either through direct access to the vulnerable component or by leveraging cross-site request forgery techniques to trick administrators into executing malicious requests.
The technical exploitation of this vulnerability occurs through the manipulation of the app_id parameter in the plugin_edit.php endpoint. The unanchored regular expression allows attackers to bypass input validation mechanisms by embedding malicious code within the parameter value, effectively circumventing the intended security controls. This flaw falls under the category of CWE-170, which specifically addresses improper input handling and regular expression vulnerabilities that can lead to code injection. The vulnerability's classification aligns with ATT&CK technique T1059.007, which describes the use of PHP for command and scripting execution. The lack of proper parameter validation combined with the unanchored regex creates a condition where an attacker can inject malicious PHP code that gets executed within the context of the web server, potentially allowing full system compromise.
The operational impact of this vulnerability is severe and potentially catastrophic for affected systems. An attacker who successfully exploits this vulnerability can execute arbitrary PHP code with the privileges of the web server process, which typically corresponds to the system user running the web application. This could lead to complete system compromise, data exfiltration, or the establishment of persistent backdoors. The requirement for administrative access or CSRF exploitation means that the vulnerability cannot be exploited by casual attackers without some form of social engineering or existing access to an administrative account. However, once an attacker gains access to an administrative session, the consequences are dire as they can modify or replace core application components, install malware, or redirect traffic to malicious destinations. The vulnerability affects the integrity and availability of the entire blogging platform and potentially the underlying server infrastructure.
Mitigation strategies for CVE-2018-9153 should focus on immediate patching of the affected Z-BlogPHP version to the latest available release that addresses this specific vulnerability. Organizations should implement proper input validation and parameter sanitization measures to prevent similar issues from occurring in other components. The fix should involve anchoring the regular expression to ensure that input matches the complete parameter value rather than partial matches, preventing injection attacks. Network segmentation and access control measures should be enforced to limit administrative access to only trusted personnel and systems. Additionally, implementing web application firewalls and intrusion detection systems can help detect and block malicious attempts to exploit this vulnerability. Security monitoring should be enhanced to detect unusual administrative activities or unauthorized modifications to plugin components, while regular security audits should be conducted to identify other potential vulnerabilities in the application's codebase. The vulnerability underscores the importance of proper input validation and the critical nature of regular security updates in maintaining application integrity.