CVE-2018-2491 in Fiori Client
Summary
by MITRE
When opening a deep link URL in SAP Fiori Client with log level set to "Debug", the client application logs the URL to the log file. If this URL contains malicious JavaScript code it can eventually run inside the built-in log viewer of the application in case user opens the viewer and taps on the hyperlink in the viewer. SAP Fiori Client version 1.11.5 in Google Play store addresses these issues and users must update to that version.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 04/12/2020
This vulnerability resides in the SAP Fiori Client application which serves as a mobile interface for accessing SAP Fiori applications. The flaw manifests when the application operates with debug logging enabled, creating a dangerous condition where deep link URLs containing malicious javascript code are recorded in log files. The vulnerability represents a classic cross-site scripting issue that exploits the application's logging mechanism to persist malicious code within its own environment. When users subsequently open the built-in log viewer and interact with the hyperlink contained within the logged URL, the embedded javascript executes within the application's context, potentially compromising the device and accessing sensitive information. This vulnerability directly maps to CWE-79 - Cross-site Scripting and aligns with ATT&CK technique T1211 - Exploitation for Defense Evasion, as the malicious code can execute without user interaction beyond the initial log file viewing. The vulnerability affects SAP Fiori Client version 1.11.5 and earlier versions available in the Google Play store, where the debug logging functionality lacks proper input sanitization and output encoding.
The technical implementation of this vulnerability exploits the application's trust in its own log output mechanism. When deep link URLs are processed with debug logging enabled, the application fails to sanitize or escape special characters within the URL before writing to the log file. This creates a situation where javascript code can be embedded within the URL and subsequently executed when the log viewer parses the content and renders hyperlinks. The vulnerability requires minimal user interaction beyond normal application usage, making it particularly dangerous as it can be triggered simply by viewing log files. The built-in log viewer component of the application does not implement proper security measures to prevent script execution when rendering hyperlinks from potentially untrusted sources, creating an execution environment where malicious code can operate with the privileges of the application itself. This represents a privilege escalation scenario where user data and application functionality become compromised.
The operational impact of this vulnerability extends beyond simple code execution to encompass potential data theft, device compromise, and unauthorized access to enterprise resources. Attackers can craft malicious deep link URLs that, when viewed in the log file, execute arbitrary javascript code that could exfiltrate data, manipulate application state, or establish persistence mechanisms. The vulnerability affects mobile device security particularly since the SAP Fiori Client often runs on devices containing sensitive enterprise information, and the log viewer functionality provides a privileged execution context. Organizations using SAP Fiori Client in enterprise environments face significant risk as this vulnerability could be exploited to gain unauthorized access to SAP systems, potentially leading to data breaches, insider threats, or lateral movement within the enterprise network. The vulnerability is particularly concerning in environments where mobile applications are used to access sensitive business applications and data. The attack surface includes not only the direct execution of malicious code but also potential exploitation of other application components through the compromised log viewer functionality.
The recommended mitigation strategy involves immediate updating of the SAP Fiori Client application to version 1.11.5 or later, which addresses the vulnerability through proper input validation and output encoding mechanisms. Organizations should also implement administrative controls to disable debug logging in production environments where the risk of malicious URL injection is higher. Security teams should monitor application logs for unusual URL patterns or attempts to inject malicious content into the logging system. Additional defensive measures include implementing network-based restrictions to prevent access to potentially malicious URLs, deploying mobile application management solutions that can control application permissions and functionality, and conducting regular security assessments of mobile applications in use. The vulnerability highlights the importance of secure coding practices in mobile applications and the need for proper input validation and output encoding even in internal application components that may not be directly exposed to external users. Organizations should also consider implementing application sandboxing and privilege separation techniques to limit the potential impact of such vulnerabilities.