CVE-2025-23193: SAP Basis Information Disclosure Flaw

CVE-2025-23193 Overview

CVE-2025-23193 is an information disclosure vulnerability affecting SAP NetWeaver Server ABAP that allows unauthenticated attackers to enumerate valid user accounts. The vulnerability stems from differential server responses based on the existence of specified users, enabling attackers to harvest valid usernames without authentication. This weakness (CWE-204: Observable Response Discrepancy) can serve as a precursor to targeted attacks such as password spraying, brute-force authentication attempts, or social engineering campaigns.

Critical Impact

Unauthenticated attackers can enumerate valid user accounts on SAP NetWeaver systems, potentially enabling targeted credential attacks against enterprise SAP environments.

Affected Products

• SAP SAP_BASIS versions 700, 701, 702
• SAP SAP_BASIS versions 731, 740
• SAP SAP_BASIS versions 750, 751, 752, 753, 754, 755, 756, 757, 758

Discovery Timeline

• 2025-02-11 - CVE-2025-23193 published to NVD
• 2025-10-23 - Last updated in NVD database

Technical Details for CVE-2025-23193

Vulnerability Analysis

This vulnerability represents a classic user enumeration flaw where the SAP NetWeaver Server ABAP application returns observably different responses depending on whether a queried username exists in the system. When an attacker sends authentication or lookup requests with various usernames, the server's response characteristics—whether through HTTP response codes, error messages, response timing, or content variations—reveal the validity of each tested username.

The vulnerability affects a wide range of SAP_BASIS versions spanning from legacy version 700 through the current version 758, indicating a long-standing architectural issue in how user validation responses are handled. While the vulnerability does not directly allow data modification or impact system availability, the information disclosed can significantly lower the barrier for subsequent attacks.

Root Cause

The root cause is classified under CWE-204: Observable Response Discrepancy. The SAP NetWeaver Server ABAP fails to implement consistent response behavior when processing requests containing user identifiers. Instead of returning uniform responses regardless of user existence, the application reveals whether accounts are valid through detectable variations in its responses. This design flaw enables attackers to systematically probe the system and build a list of valid user accounts.

Attack Vector

The attack can be conducted remotely over the network without any authentication requirements. An attacker can exploit this vulnerability by:

1. Identifying an endpoint that accepts user identifiers as input
2. Sending multiple requests with different potential usernames
3. Analyzing response characteristics (timing, content, status codes, error messages) to differentiate between valid and invalid users
4. Compiling a list of confirmed valid usernames for use in subsequent attacks

The vulnerability manifests in the user validation mechanism of SAP NetWeaver Server ABAP. When processing requests containing user identifiers, the server returns distinguishable responses based on whether the specified user exists in the system. This observable discrepancy allows attackers to enumerate valid accounts. For detailed technical information, refer to SAP Note #3561264.

Detection Methods for CVE-2025-23193

Indicators of Compromise

• High volume of authentication or user lookup requests from a single IP address targeting multiple usernames
• Sequential or dictionary-based username patterns in request logs
• Requests probing common SAP default or service account names
• Unusual access patterns to user validation endpoints from external networks

Detection Strategies

• Monitor authentication logs for patterns indicating systematic user enumeration attempts
• Implement rate limiting and alerting on endpoints that accept username parameters
• Deploy web application firewall rules to detect and block enumeration patterns
• Enable enhanced logging on SAP NetWeaver systems to capture detailed request information

Monitoring Recommendations

• Configure SAP Security Audit Log (SAL) to capture failed authentication events
• Establish baseline metrics for authentication request volumes and alert on anomalies
• Integrate SAP logs with SIEM solutions for correlation with other security events
• Monitor for reconnaissance activity targeting SAP infrastructure from threat intelligence feeds

How to Mitigate CVE-2025-23193

Immediate Actions Required

• Review and apply the security patch referenced in SAP Note #3561264
• Implement rate limiting on authentication and user lookup endpoints
• Restrict network access to SAP NetWeaver systems to authorized IP ranges where possible
• Enable enhanced logging to detect potential exploitation attempts

Patch Information

SAP has released a security patch addressing this vulnerability. Organizations should apply the patch available through SAP Security Patch Day. The fix ensures consistent server responses regardless of user existence, eliminating the observable discrepancy that enables enumeration. Refer to SAP Note #3561264 for detailed patching instructions and prerequisites.

Workarounds

• Implement network-level access controls to limit exposure of SAP NetWeaver endpoints to trusted networks
• Deploy a web application firewall (WAF) with rules to detect and block enumeration attempts
• Configure account lockout policies to mitigate the impact of credential attacks following enumeration
• Consider implementing CAPTCHA or similar mechanisms on authentication endpoints to slow automated attacks

# Example: Configure SAP ICM parameters to enhance logging
# Add to DEFAULT.PFL or instance profile
icm/HTTP/logging_0 = PREFIX=/, LOGFILE=$(DIR_LOGGING)/access_log, MAXSIZEKB=10000, MAXFILES=7, FILEWRAP=on
icm/HTTP/logging_client_0 = PREFIX=/, LOGFILE=$(DIR_LOGGING)/client_log, MAXSIZEKB=10000, MAXFILES=7
# Enable security audit logging
rsau/enable = 1
rsau/selection_slots = 10