CVE-2018-19651 in Email Marketer
Summary
by MITRE
admin/functions/remote.php in Interspire Email Marketer through 6.1.6 has Server Side Request Forgery (SSRF) via a what=importurl&url= request with an http or https URL. This also allows reading local files with a file: URL.
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Analysis
by VulDB Data Team • 04/16/2020
The vulnerability identified as CVE-2018-19651 represents a critical server side request forgery flaw within Interspire Email Marketer version 6.1.6 and earlier. This vulnerability exists in the remote.php file located within the admin/functions directory of the application. The flaw manifests when the application processes requests containing specific parameters including what=importurl and url= which can accept http, https, or file protocol URLs. The vulnerability operates under CWE-918 which specifically addresses server side request forgery conditions where an attacker can manipulate the application to make requests to arbitrary destinations. This type of vulnerability falls squarely within the ATT&CK technique T1071.004 for application layer protocol tunneling and T1566 for phishing with a link.
The technical implementation of this vulnerability allows attackers to exploit the application's remote import functionality to make unauthorized requests to internal systems or access local files. When an attacker submits a request with what=importurl and a url parameter containing an http or https URL, the application will make a request to that external destination. However, the vulnerability extends beyond external requests to include local file access when the url parameter uses the file: protocol. This means an attacker can potentially read sensitive local files on the server such as configuration files, database credentials, or other system files that should remain protected. The vulnerability stems from insufficient input validation and sanitization of the URL parameter, allowing arbitrary protocol schemes to be processed without proper authorization checks.
The operational impact of this vulnerability is severe and multifaceted. Attackers can leverage this flaw to perform reconnaissance on internal network systems by making requests to internal IP addresses or ports that would normally be inaccessible from the internet. The ability to read local files provides attackers with potential access to database connection strings, application configuration files, and other sensitive information that could lead to further compromise. Additionally, this vulnerability could enable attackers to pivot within the network, potentially accessing other systems or services running on the same server. The vulnerability essentially provides a backdoor mechanism for attackers to bypass normal network security controls and access resources that should be protected from external access. The impact extends beyond immediate data theft to potential complete system compromise, especially if the application runs with elevated privileges or has access to sensitive data repositories.
Mitigation strategies for this vulnerability should focus on implementing strict input validation and sanitization of URL parameters within the application. The most effective approach involves validating that only allowed protocol schemes are permitted, specifically rejecting file:, ftp:, or other potentially dangerous protocols in the URL parameter. Organizations should implement proper access controls and network segmentation to limit what internal resources can be accessed through the application. Regular security updates and patches should be applied immediately upon release to address known vulnerabilities. Additionally, network monitoring should be enhanced to detect unusual outbound requests from the application server that might indicate exploitation attempts. The vulnerability highlights the importance of principle of least privilege and proper input validation as fundamental security controls. Security teams should also consider implementing web application firewalls to filter malicious requests and conduct regular security assessments to identify similar vulnerabilities in other applications. The remediation process should include thorough code review to ensure no other similar input validation flaws exist within the application's functionality.