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The vulnerability stems from insecure deserialization of Java objects in the web‑based management interface of Cisco Secure Firewall Management Center (FMC). The affected endpoint accepts serialized Java byte streams without validating the incoming data. When an attacker sends a crafted `java.io.Serializable` object, the application’s Java runtime automatically reconstructs the object during deserialization. This process can be abused to instantiate arbitrary classes and execute system commands with the privileges of the FMC process—typically root. The flaw resides in the REST API or the web UI backend, where the `ObjectInputStream` is invoked on user‑supplied data. By leveraging gadget chains (e.g., common Apache Commons Collections or Spring dependencies present in the classpath), an attacker can achieve remote code execution. The exploitation does not require authentication; a single HTTP POST request containing the malicious serialized payload triggers the deserialization. Because the FMC management interface is often exposed to internal networks, and sometimes publicly, the attack surface is significant. Successful exploitation yields full control over the appliance, enabling lateral movement, persistence, or data exfiltration. Cisco confirmed that the issue is present in versions prior to 7.2.5, 7.4.1, and 7.6.0. The CVSS score of 10.0 reflects the combination of network attack vector, low complexity, no privileges, and no user interaction, with a complete impact on confidentiality, integrity, and availability.
dailycve form (3 words max each line):
Platform: Cisco FMC
Version: Multiple prior releases
Vulnerability: Insecure deserialization RCE
Severity: Critical
Date: 2024‑03‑27
Prediction: March 27 2024
What Undercode Say:
Analytics
Check FMC version via CLI admin@fmc:~$ show version Detect exposed deserialization endpoint (example) curl -X POST https://<fmc-ip>/api/deserialize-endpoint \ -H "Content-Type: application/x-java-serialized-object" \ --data-binary @payload.ser -k Monitor for anomalous Java deserialization attempts sudo tcpdump -i any -A 'tcp port 443' | grep -i "aced0005"
Exploit
- Identify vulnerable FMC version (pre‑7.2.5 / 7.4.1 / 7.6.0).
- Craft a malicious Java serialized object using ysoserial with a suitable gadget (e.g.,
CommonsCollections6). - Send an HTTP POST request to the vulnerable endpoint (e.g.,
/api/fmc_platform/v1/...) with the payload as the body. - Upon deserialization, the payload executes a reverse shell or arbitrary command as root.
Protection from this CVE
- Upgrade to FMC version 7.2.5, 7.4.1, 7.6.0 or later.
- Restrict management interface access to trusted IPs using ACLs.
- Disable the web‑based management interface if not required.
- Deploy network IPS signatures that detect Java deserialization patterns (
aced0005). - Enable HTTP inspection on firewalls to block serialized Java objects.
Impact
- Full system compromise (root privileges).
- Unauthorized configuration changes, firewall policy tampering.
- Lateral movement to managed firewalls (FTD/ASA).
- Persistent backdoor installation.
- Data breach of network topology and sensitive logs.
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Sources:
Reported By: www.cve.org
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