CVE-2020-6293 in NetWeaver
Summary
by MITRE
SAP NetWeaver (Knowledge Management), versions - 7.30, 7.31, 7.40, 7.50, allows an unauthenticated attacker to upload a malicious file and also to access, modify or make unavailable existing files but the impact is limited to the files themselves and is restricted by other policies such as access control lists and other upload file size restrictions, leading to Unrestricted File Upload.
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Analysis
by VulDB Data Team • 11/08/2020
SAP NetWeaver Knowledge Management systems running versions 7.30, 7.31, 7.40, and 7.50 contain a critical security vulnerability that enables unauthenticated attackers to perform unrestricted file upload operations. This vulnerability stems from insufficient validation mechanisms within the file upload functionality, allowing malicious actors to bypass normal security controls and execute arbitrary file uploads without proper authentication. The flaw exists in the application's handling of file upload requests where input validation is either absent or inadequate, creating a pathway for attackers to inject malicious content into the system.
The technical implementation of this vulnerability resides in the application's file handling processes where proper sanitization and validation checks are missing or improperly configured. Attackers can exploit this weakness by crafting specially formatted upload requests that circumvent the normal file type restrictions and size limitations that should normally protect the system. This vulnerability aligns with CWE-434 which specifically addresses the issue of unrestricted file upload where applications fail to properly validate or restrict file types and content during upload operations. The flaw represents a fundamental breakdown in the principle of least privilege and input validation that should be enforced at multiple layers of the application architecture.
The operational impact of this vulnerability is significant despite its limited scope as described in the original CVE. While the attack is restricted by existing access control lists and upload file size limitations, the potential for exploitation remains high given that attackers can still upload malicious files that could be executed within the application context. This creates a vector for further attacks including but not limited to web shell deployment, cross-site scripting attacks, and potential privilege escalation within the constrained environment. The vulnerability enables attackers to access, modify, or make unavailable existing files, which can lead to data integrity compromise and service disruption. From an attack chain perspective, this vulnerability maps to multiple ATT&CK techniques including T1190 for exploitation of vulnerabilities, T1059 for command execution, and T1486 for data encryption for ransom.
Mitigation strategies should focus on implementing comprehensive input validation and sanitization mechanisms at the application level to ensure all uploaded files are properly verified against allowed file types and content. Organizations should immediately implement proper access controls and authentication mechanisms to restrict file upload capabilities to authorized users only. The system configuration should enforce strict file type restrictions, implement content inspection for uploaded files, and establish proper file storage segregation. Additionally, regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other components of the SAP ecosystem. Organizations should also consider implementing network-level restrictions and monitoring to detect suspicious upload activities. The vulnerability demonstrates the critical importance of defense in depth strategies where multiple security controls work together to protect against various attack vectors. This particular weakness highlights the necessity of following secure coding practices and implementing proper security controls during the development lifecycle rather than relying solely on runtime protections.