CVE-2025-2776: SysAid On-Prem XXE Vulnerability

CVE-2025-2776 Overview

CVE-2025-2776 is an unauthenticated XML External Entity (XXE) vulnerability affecting SysAid On-Prem versions 23.3.40 and earlier. The vulnerability exists in the Server URL processing functionality, allowing remote attackers to exploit improper XML parsing to achieve administrator account takeover and access sensitive file read primitives without authentication.

Critical Impact

This vulnerability is actively exploited in the wild and has been added to the CISA Known Exploited Vulnerabilities (KEV) catalog. Unauthenticated attackers can leverage this XXE flaw to take over administrator accounts and read arbitrary files from affected SysAid On-Prem installations.

Affected Products

• SysAid On-Prem versions <= 23.3.40
• SysAid On-Prem (cpe:2.3:a:sysaid:sysaid:::::on-premises:::*)

Discovery Timeline

• 2025-05-07 - CVE-2025-2776 published to NVD
• 2025-10-27 - Last updated in NVD database

Technical Details for CVE-2025-2776

Vulnerability Analysis

This XML External Entity (XXE) vulnerability (CWE-611) resides in the Server URL processing functionality of SysAid On-Prem. The application fails to properly configure its XML parser to disable external entity resolution, allowing attackers to inject malicious XML payloads that reference external entities. This architectural weakness enables unauthenticated remote attackers to exploit the vulnerability across the network without any user interaction required.

The impact of successful exploitation is severe, potentially compromising confidentiality through arbitrary file reads, integrity through administrator account takeover, and system availability. The vulnerability requires no privileges and can be exploited remotely, making it particularly dangerous for internet-exposed SysAid installations.

Root Cause

The root cause is improper restriction of XML External Entity Reference (CWE-611). The XML parser used in the Server URL processing functionality does not disable Document Type Definition (DTD) processing or external entity resolution. This allows malicious XML input containing entity declarations that reference external resources, local files, or internal network endpoints to be processed by the application.

Attack Vector

The vulnerability is exploited via network-based attacks targeting the Server URL processing functionality. An unauthenticated attacker can craft malicious XML payloads containing external entity declarations that, when processed by the vulnerable XML parser, cause the server to:

1. Read arbitrary local files from the server filesystem
2. Make outbound connections to attacker-controlled servers (enabling data exfiltration)
3. Access internal network resources via Server-Side Request Forgery (SSRF)
4. Potentially achieve administrator account takeover through retrieved credentials or session tokens

The attack requires no authentication, making all exposed SysAid On-Prem installations at risk. For detailed technical analysis of the exploitation mechanics, see the Watchtowr RCE Analysis.

Detection Methods for CVE-2025-2776

Indicators of Compromise

• Unusual XML payloads in web server logs containing DOCTYPE declarations or ENTITY references
• Unexpected outbound connections from the SysAid server to external hosts
• File access attempts for sensitive system files such as /etc/passwd, /etc/shadow, or Windows configuration files
• Anomalous administrator account activity or unauthorized privilege changes
• Error messages in application logs related to XML parsing failures or external resource access

Detection Strategies

• Monitor inbound HTTP requests to the SysAid On-Prem server for XML payloads containing <!DOCTYPE or <!ENTITY declarations
• Implement Web Application Firewall (WAF) rules to detect and block XXE attack patterns
• Review authentication logs for unexpected administrator logins or account modifications
• Deploy network monitoring to identify unusual DNS queries or HTTP connections originating from the SysAid server

Monitoring Recommendations

• Enable verbose logging for the SysAid application and web server components
• Configure SIEM rules to alert on XML injection patterns and suspicious file access attempts
• Monitor for CISA KEV-related threat intelligence feeds referencing CVE-2025-2776
• Implement file integrity monitoring on sensitive configuration files that may be targeted for exfiltration

How to Mitigate CVE-2025-2776

Immediate Actions Required

• Upgrade SysAid On-Prem to version 24.40.60 or later immediately as documented in the SysAid Documentation Guide
• Restrict network access to SysAid On-Prem servers to trusted IP ranges only
• If immediate patching is not possible, consider temporarily taking the affected system offline
• Review administrator accounts for unauthorized changes or suspicious activity
• Check for indicators of compromise before and after applying patches

Patch Information

SysAid has released security updates addressing this vulnerability. Organizations should upgrade to SysAid On-Prem version 24.40.60 or later. Detailed upgrade instructions are available in the SysAid Documentation Guide. Given that this vulnerability is actively exploited and listed in the CISA Known Exploited Vulnerabilities catalog, patching should be treated as an emergency priority.

Workarounds

• Implement network segmentation to isolate SysAid On-Prem servers from untrusted networks
• Deploy a Web Application Firewall (WAF) with XXE attack detection rules as a temporary protective layer
• Restrict inbound access to the SysAid server using firewall rules, limiting connections to known administrative IP addresses
• Disable internet-facing access to the SysAid On-Prem application until patching is complete

# Example: Restrict access to SysAid using iptables (adjust IP ranges as needed)
# Allow only trusted administrative networks
iptables -A INPUT -p tcp --dport 8080 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -s 192.168.0.0/16 -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP

# Save the rules
iptables-save > /etc/iptables/rules.v4