CVE-2018-7748 in ServiceNow
Summary
by MITRE
report_viewer.do in ServiceNow Release Jakarta Patch 8 and earlier allows remote attackers to execute arbitrary code via '${xyz}' Glide Scripting Injection in the sysparm_media parameter.
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Analysis
by VulDB Data Team • 03/13/2020
The vulnerability identified as CVE-2018-7748 resides within the ServiceNow Jakarta release series through Patch 8, specifically affecting the report_viewer.do web application component. This flaw represents a critical security weakness that enables remote attackers to execute arbitrary code on affected systems. The vulnerability manifests through improper input validation and sanitization mechanisms within the Glide scripting engine, which processes user-supplied parameters without adequate security controls. The attack vector specifically targets the sysparm_media parameter, which is utilized in the report viewer functionality to determine media output formats for generated reports. When an attacker crafts malicious input containing '${xyz}' patterns within this parameter, the system's scripting engine interprets these expressions as executable code rather than benign input, creating a dangerous injection opportunity.
The technical implementation of this vulnerability stems from ServiceNow's Glide scripting engine failing to properly sanitize user input before processing it within the report generation context. The '${xyz}' syntax is a legitimate Glide scripting construct used for variable substitution and dynamic content generation, but when exposed to unfiltered user input, attackers can manipulate this feature to execute arbitrary server-side code. This represents a classic server-side request forgery and code injection vulnerability that falls under the CWE-94 category of "Improper Control of Generation of Code ('Code Injection')" and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell." The vulnerability's exploitation requires minimal privileges since it operates at the application layer without requiring authentication, making it particularly dangerous in environments where ServiceNow instances are exposed to untrusted networks.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with complete control over the affected ServiceNow instance and potentially the underlying infrastructure. Successful exploitation allows threat actors to access sensitive data, modify system configurations, escalate privileges, and establish persistent access through the compromised reporting functionality. The vulnerability affects organizations using ServiceNow's Jakarta release series, which includes numerous enterprise customers across various sectors including finance, healthcare, and government services. The consequences include potential data breaches, regulatory compliance violations, and significant operational disruption. Organizations may face extended forensic investigations, legal liability, and reputational damage when such vulnerabilities are exploited in production environments. The vulnerability's impact is amplified by ServiceNow's widespread adoption across enterprise environments where it serves as a core platform for IT service management, customer service, and business operations.
Mitigation strategies for CVE-2018-7748 require immediate patch application from ServiceNow, specifically targeting Jakarta Patch 8 or later versions that contain the necessary security fixes. Organizations should implement network segmentation to limit access to ServiceNow instances and restrict the exposure of report_viewer.do endpoints to trusted networks only. Input validation should be enhanced through custom filters that sanitize the sysparm_media parameter and reject suspicious scripting patterns. Security monitoring should be enhanced to detect anomalous requests containing '${xyz}' patterns or other potential injection attempts. Additionally, organizations should conduct regular vulnerability assessments and penetration testing to identify similar weaknesses in their ServiceNow implementations. The implementation of web application firewalls and security monitoring solutions can provide additional layers of protection against exploitation attempts. Organizations should also review and update their incident response procedures to ensure rapid detection and remediation of such vulnerabilities. Compliance with industry standards such as NIST SP 800-53 and ISO 27001 requires organizations to maintain current security patches and implement proper vulnerability management processes to address threats like CVE-2018-7748.