CVE-2017-18228 in Remedy AR System
Summary
by MITRE
Remedy Mid Tier in BMC Remedy AR System 9.1 allows XSS via the ATTKey parameter in an arsys/servlet/AttachServlet request.
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Analysis
by VulDB Data Team • 01/12/2020
The vulnerability CVE-2017-18228 represents a cross-site scripting flaw within the Remedy Mid Tier component of BMC Remedy AR System version 9.1. This security weakness resides in the AttachServlet endpoint which processes file attachment requests through the arsys/servlet/AttachServlet path. The vulnerability specifically manifests when the ATTKey parameter is manipulated within HTTP requests, creating an avenue for malicious actors to inject malicious scripts into the application's response. This flaw falls under the category of client-side injection vulnerabilities and directly impacts the integrity of user sessions and data confidentiality within the system. The ATTKey parameter serves as a critical identifier for attachment handling processes, making it a prime target for exploitation.
The technical implementation of this vulnerability stems from inadequate input validation and output encoding within the AttachServlet component. When the system receives a request containing a maliciously crafted ATTKey parameter, it fails to properly sanitize the input before incorporating it into the HTTP response. This omission allows attackers to inject HTML tags, JavaScript code, or other malicious payloads that execute within the context of legitimate user sessions. The vulnerability is particularly concerning because it operates at the servlet level, meaning it can affect all users interacting with the attachment functionality regardless of their authentication status or role within the system. The flaw is classified as CWE-79 - Cross-site Scripting, which represents one of the most prevalent and dangerous web application vulnerabilities according to the CWE catalog.
The operational impact of this vulnerability extends beyond simple data exposure, potentially enabling attackers to perform session hijacking, steal sensitive information, or redirect users to malicious websites. An attacker could craft a malicious link containing the vulnerable ATTKey parameter that, when clicked by an authenticated user, would execute arbitrary JavaScript code within the user's browser session. This could lead to unauthorized access to other system resources, modification of data, or complete compromise of user sessions. The vulnerability affects the entire BMC Remedy AR System 9.1 environment and could be exploited through various attack vectors including email links, web forms, or direct HTTP request manipulation. According to ATT&CK framework, this vulnerability maps to T1059 - Command and Scripting Interpreter and T1566 - Phishing, as it enables the delivery of malicious payloads through web-based attack vectors. The potential for privilege escalation exists when the vulnerable system processes attachments from users with elevated privileges, making this attack particularly dangerous in enterprise environments.
Mitigation strategies for CVE-2017-18228 should focus on immediate input validation and output encoding improvements within the AttachServlet component. Organizations should implement strict parameter validation for the ATTKey field, ensuring that all input conforms to expected formats and rejects any suspicious or malformed data. The system should employ comprehensive output encoding mechanisms to prevent the execution of any embedded scripts in HTTP responses. Security patches provided by BMC should be applied immediately, as the vendor likely released a fix addressing the input sanitization issues. Network-level protections such as web application firewalls can provide additional defense-in-depth measures by monitoring for suspicious ATTKey parameter patterns. Regular security testing including dynamic application security testing and manual penetration testing should be conducted to identify similar vulnerabilities in other servlet components. Implementation of Content Security Policy headers can provide browser-level protection against script execution, while proper access controls and user session management can limit the potential damage from successful exploitation attempts. Organizations should also establish monitoring procedures to detect unusual attachment handling patterns that might indicate exploitation attempts.