CVE-2025-27493
📋 TL;DR
This vulnerability allows authenticated local administrators on SiPass integrated access control systems to escalate privileges by injecting arbitrary commands through the telnet interface. The injected commands execute with root privileges, potentially giving attackers full system control. Only SiPass AC5102 (ACC-G2) and ACC-AP devices running versions below V6.4.9 are affected.
💻 Affected Systems
- SiPass integrated AC5102 (ACC-G2)
- SiPass integrated ACC-AP
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
An authenticated attacker gains full root access to the access control system, allowing them to modify security configurations, disable access controls, exfiltrate credential data, or use the device as a pivot point into the network.
Likely Case
A malicious insider or compromised administrator account uses command injection to bypass intended privilege restrictions and gain elevated system access for persistence or data theft.
If Mitigated
With proper network segmentation, telnet disabled, and strong authentication controls, the attack surface is significantly reduced, though the vulnerability remains present in the software.
🎯 Exploit Status
Exploitation requires authenticated access to the telnet interface and knowledge of vulnerable command parameters. No public exploit code is currently available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: V6.4.9 or later
Vendor Advisory: https://cert-portal.siemens.com/productcert/html/ssa-515903.html
Restart Required: No
Instructions:
1. Download firmware V6.4.9 or later from Siemens support portal. 2. Backup current configuration. 3. Upload new firmware through web interface. 4. Apply configuration backup if needed. 5. Verify successful update.
🔧 Temporary Workarounds
Disable Telnet Access
allDisable telnet service and use only secure management interfaces like SSH or HTTPS
telnet disable
service telnet stop
Restrict Network Access
allImplement network segmentation to restrict telnet access to authorized management networks only
iptables -A INPUT -p tcp --dport 23 -s TRUSTED_NETWORK -j ACCEPT
iptables -A INPUT -p tcp --dport 23 -j DROP
🧯 If You Can't Patch
- Disable telnet service completely and use alternative secure management methods
- Implement strict network segmentation to isolate affected devices from general network access
- Enforce strong authentication policies and monitor administrator account activity
- Regularly audit telnet logs for suspicious command injection attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface or CLI: System > About > Firmware Version. If version is below V6.4.9, device is vulnerable.Check Version:
show version or cat /etc/versionVerify Fix Applied:
After patching, verify firmware version shows V6.4.9 or later. Test telnet command injection attempts should no longer succeed.📡 Detection & Monitoring
Log Indicators:
- Unusual telnet login attempts
- Suspicious command sequences in telnet logs
- Multiple failed privilege escalation attempts
- Unexpected system configuration changes
Network Indicators:
- Telnet connections from unauthorized sources
- Unusual outbound connections from access control devices
- Telnet traffic containing command injection patterns
SIEM Query:
source="telnet_logs" AND (command="*;*" OR command="*|*" OR command="*`*" OR command="*$(*")