CVE-2021-33691 in NetWeaver Development Infrastructure
Summary
by MITRE • 09/16/2021
NWDI Notification Service versions - 7.31, 7.40, 7.50, does not sufficiently encode user-controlled inputs, resulting in Cross-Site Scripting (XSS) vulnerability.SAP NetWeaver Development Infrastructure Notification Service allows a threat actor to send crafted scripts to a victim. If the victim has an active session when the crafted script gets executed, the threat actor could compromise information in victims session, and gain access to some sensitive information also.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 09/19/2021
The CVE-2021-33691 vulnerability affects SAP NetWeaver Development Infrastructure Notification Service versions 7.31, 7.40, and 7.50, representing a critical cross-site scripting flaw that exploits insufficient input validation mechanisms. This vulnerability resides within the notification service component that handles user-controlled data inputs, creating an attack vector where malicious scripts can be injected and executed within the context of a victim's browser session. The flaw manifests when the system fails to properly encode or sanitize user-provided data before rendering it in web responses, allowing attackers to inject malicious JavaScript code that persists in the notification system.
The technical exploitation of this vulnerability follows the typical XSS attack pattern where threat actors craft malicious payloads containing script tags or other malicious code that gets stored in the notification service and subsequently executed when legitimate users view the affected notifications. The vulnerability specifically targets the input handling mechanisms within the NWDI Notification Service, which processes user inputs without adequate sanitization or encoding, creating a persistent XSS condition. This weakness is classified under CWE-79 as "Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')", which directly aligns with the standard vulnerability classification for XSS issues in web applications.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the capability to hijack active user sessions and access sensitive information within the victim's browser context. When a compromised session executes the malicious script, threat actors can potentially access session cookies, view sensitive data, perform unauthorized actions on behalf of the victim, and gain access to privileged information within the SAP environment. The attack scenario typically involves sending crafted notification messages to users who have active sessions, where the malicious payload executes in their browser context and establishes a foothold for further exploitation.
The security implications of this vulnerability are particularly severe in enterprise environments where SAP systems handle sensitive business data and user credentials. Attackers can leverage this flaw to perform session hijacking attacks, steal authentication tokens, and potentially escalate privileges within the SAP infrastructure. The vulnerability creates a persistent threat vector that can be exploited across multiple users within the same system, making it particularly dangerous for organizations with extensive SAP deployments. Organizations should consider implementing comprehensive input validation and output encoding mechanisms to prevent such attacks, while also monitoring for suspicious notification patterns that might indicate exploitation attempts. The attack surface is further expanded by the fact that this vulnerability affects multiple versions of the NWDI Notification Service, requiring organizations to assess their entire SAP infrastructure for similar encoding deficiencies and implement appropriate security controls including web application firewalls and regular security assessments to prevent exploitation.