CVE-2017-7732 in FortiMail
Summary
by MITRE
A reflected Cross-Site Scripting (XSS) vulnerability in Fortinet FortiMail 5.1 and earlier, 5.2.0 through 5.2.9, and 5.3.0 through 5.3.9 customized pre-authentication webmail login page allows attacker to inject arbitrary web script or HTML via crafted HTTP requests.
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Analysis
by VulDB Data Team • 01/20/2021
The vulnerability identified as CVE-2017-7732 represents a critical reflected cross-site scripting flaw within Fortinet FortiMail email security appliances across multiple version ranges including 5.1 and earlier, 5.2.0 through 5.2.9, and 5.3.0 through 5.3.9. This issue specifically affects the customized pre-authentication webmail login page component of the FortiMail system, creating a significant security risk that can be exploited by remote attackers without requiring any authentication credentials. The vulnerability stems from inadequate input validation and output encoding mechanisms within the web application's handling of HTTP request parameters, particularly those related to the login page functionality.
The technical implementation of this vulnerability occurs when the FortiMail appliance fails to properly sanitize or encode user-supplied input data that is subsequently reflected back to the victim's browser within the web page content. When an attacker crafts a malicious HTTP request containing specially formatted script code within parameters such as username, password, or other login form fields, the application processes these inputs without adequate filtering mechanisms. The reflected nature of this vulnerability means that the malicious script code is immediately executed within the victim's browser context when they click on the crafted link or navigate to the malicious page. This occurs because the web application directly incorporates user-provided data into the HTTP response without proper sanitization, allowing the attacker's payload to be interpreted as executable JavaScript code rather than plain text.
The operational impact of CVE-2017-7732 extends beyond simple script execution, as it provides attackers with the capability to perform various malicious activities within the victim's browser session. Attackers can leverage this vulnerability to steal session cookies, redirect users to malicious websites, inject phishing content, or perform actions on behalf of authenticated users. The pre-authentication nature of the vulnerability means that attackers can exploit it even before users have established legitimate sessions, making it particularly dangerous for email security environments where user trust and authentication are paramount. The vulnerability affects the webmail interface specifically, which means that successful exploitation could compromise email communications, access sensitive data, or provide attackers with a foothold for further attacks within the network infrastructure.
Organizations utilizing affected FortiMail versions should implement immediate mitigations including applying the latest security patches provided by Fortinet, implementing web application firewalls to detect and block malicious payloads, and conducting thorough security assessments of their email infrastructure. The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications, and corresponds to techniques described in the MITRE ATT&CK framework under the T1059.007 sub-technique for "Scripting" and T1566.001 for "Phishing". Network segmentation and monitoring of suspicious HTTP traffic patterns can help detect exploitation attempts, while user education regarding suspicious email links and webmail navigation practices remains essential for comprehensive defense. The vulnerability demonstrates the critical importance of proper input validation and output encoding in web application security, particularly in security appliances where user interaction with web interfaces is essential for legitimate administrative and user functions.