CVE-2021-33690 in NetWeaver Development Infrastructure
Summary
by MITRE • 09/16/2021
Server-Side Request Forgery (SSRF) vulnerability has been detected in the SAP NetWeaver Development Infrastructure Component Build Service versions - 7.11, 7.20, 7.30, 7.31, 7.40, 7.50The SAP NetWeaver Development Infrastructure Component Build Service allows a threat actor who has access to the server to perform proxy attacks on server by sending crafted queries. Due to this, the threat actor could completely compromise sensitive data residing on the Server and impact its availability.Note: The impact of this vulnerability depends on whether SAP NetWeaver Development Infrastructure (NWDI) runs on the intranet or internet. The CVSS score reflects the impact considering the worst-case scenario that it runs on the internet.
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Analysis
by VulDB Data Team • 09/19/2021
The CVE-2021-33690 vulnerability represents a critical server-side request forgery flaw within SAP NetWeaver Development Infrastructure Component Build Service across multiple versions including 7.11, 7.20, 7.30, 7.31, 7.40, and 7.50. This vulnerability falls under the Common Weakness Enumeration category CWE-918, which specifically addresses server-side request forgery conditions where an attacker can manipulate a server into making unintended requests to internal or external systems. The flaw exists in the build service component that processes requests from developers and administrators, creating a pathway for malicious actors to exploit the system's trust relationships and bypass normal access controls.
The technical implementation of this vulnerability allows threat actors with server access to craft malicious requests that leverage the build service's functionality to perform proxy attacks against internal systems. The attacker can manipulate the service to make HTTP requests to arbitrary destinations, potentially accessing internal resources that should normally be isolated from external access. This occurs because the service fails to properly validate and sanitize user-supplied input that determines the target of outbound requests, creating an attack surface where internal network resources become accessible through the compromised server. The vulnerability is particularly dangerous because it operates at the server level, meaning that successful exploitation can lead to complete compromise of the system and its sensitive data.
The operational impact of this vulnerability extends beyond simple data exposure to include potential service disruption and unauthorized access to internal network resources. When SAP NetWeaver Development Infrastructure operates on the internet, the CVSS score reflects the maximum potential damage, as attackers can leverage this vulnerability from outside the organization's network perimeter. The compromise can result in unauthorized access to internal databases, file systems, and other sensitive resources that the build service might have access to. Additionally, the vulnerability can be used to perform reconnaissance activities against internal systems, potentially leading to further exploitation opportunities and lateral movement within the network. The availability impact is significant as attackers can potentially cause service disruption by targeting critical internal systems through the build service.
Organizations should implement multiple layers of defense to mitigate this vulnerability, starting with immediate patching of affected SAP NetWeaver versions to the latest security releases. Network segmentation and firewall rules should be implemented to restrict access to the build service component, particularly limiting outbound connections from the server to internal resources. Input validation and sanitization should be strengthened throughout the application to prevent malicious requests from being processed, with particular attention to any user-controllable parameters that might influence outbound request targets. The ATT&CK framework categorizes this vulnerability under T1071.004 Application Layer Protocol: DNS and T1566.002 Phishing: Spearphishing Attachment, as attackers may use this vulnerability to establish persistent access and exfiltrate data from internal systems. Regular security monitoring and log analysis should be enhanced to detect unusual outbound requests that might indicate exploitation attempts, with specific attention to requests targeting internal IP ranges or unusual domains. Additionally, implementing network access controls and restricting the build service's ability to make arbitrary outbound connections significantly reduces the attack surface and potential impact of this vulnerability.