CVE-2020-28977 in Canto Plugin
Summary
by MITRE • 11/30/2020
The Canto plugin 1.3.0 for WordPress contains blind SSRF vulnerability. It allows an unauthenticated attacker can make a request to any internal and external server via /includes/lib/get.php?subdomain=SSRF.
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Analysis
by VulDB Data Team • 01/02/2025
The CVE-2020-28977 vulnerability represents a critical blind server-side request forgery flaw within the Canto plugin version 1.3.0 for WordPress platforms. This vulnerability exists in the plugin's handling of user input through the /includes/lib/get.php endpoint where the subdomain parameter is processed without adequate validation or sanitization. The flaw allows unauthenticated attackers to construct malicious requests that can traverse network boundaries and potentially access internal systems that would otherwise be protected by firewalls or network segmentation. The vulnerability specifically manifests when the plugin processes the subdomain parameter, which is then used to construct HTTP requests without proper input validation mechanisms.
This blind SSRF vulnerability falls under the Common Weakness Enumeration category CWE-918, which specifically addresses server-side request forgery vulnerabilities where attackers can manipulate the target of HTTP requests. The ATT&CK framework categorizes this as a technique for Initial Access and Lateral Movement through the use of web application vulnerabilities. The vulnerability's impact is exacerbated by the fact that it requires no authentication credentials to exploit, making it particularly dangerous for publicly accessible WordPress installations. The attack vector leverages the plugin's internal processing logic where external user-controllable parameters are directly incorporated into HTTP request construction, creating a pathway for attackers to probe internal network resources and potentially exfiltrate sensitive data.
The operational implications of this vulnerability are severe for WordPress administrators and system operators. An attacker can use this flaw to enumerate internal services, conduct port scanning, or even attempt to access sensitive internal resources such as databases, management interfaces, or other internal servers that are not directly exposed to the internet. The blind nature of the vulnerability means that attackers cannot directly observe the responses from their crafted requests, but they can infer information through timing attacks or by using techniques that generate different network responses based on the target system's behavior. This makes the vulnerability particularly dangerous as it can be used for reconnaissance purposes to map internal network topologies and identify potential additional attack vectors. The impact extends beyond simple information disclosure to potentially enabling more sophisticated attacks including data exfiltration, service disruption, or even privilege escalation within the compromised WordPress environment.
Mitigation strategies for CVE-2020-28977 should prioritize immediate plugin updates to versions that address the SSRF vulnerability through proper input validation and sanitization. Administrators should implement network-level restrictions to prevent outbound connections from WordPress installations to internal resources, particularly by blocking access to common internal ports and services. The use of web application firewalls or security monitoring solutions can help detect and prevent exploitation attempts by monitoring for suspicious parameter patterns in the affected endpoint. Additionally, implementing proper access controls and network segmentation can limit the potential impact of successful exploitation attempts. Security teams should also conduct comprehensive vulnerability assessments to identify other potentially affected plugins or components within the WordPress environment and ensure that all third-party software is regularly updated to address known security vulnerabilities. The remediation process should include thorough testing of updated plugin versions to ensure that the fix does not introduce compatibility issues with existing functionality while maintaining the security posture of the overall WordPress installation.