CVE-2025-20265

Classification basis

The script only performs read-only API calls to check the FMC version and compares it against a known-affected list. It does not send any exploit payload or attempt to execute commands on the target. The README explicitly states 'No exploit code — this tool does not attempt to exploit anything or run commands on the target.' The optional --poc flag prints a local marker without transmitting it. This is a vulnerability scanner, not an exploit.

Requirements

• Valid FMC credentials with API access are required to authenticate and query the server version.fmc_cve2025_20265_checker.py:49-59fmc_cve2025_20265_checker.py:143-144

Observed behavior

• Authenticates to the FMC REST API endpoint /api/fmc_platform/v1/auth/generatetoken using provided credentials.fmc_cve2025_20265_checker.py:49-59
• Retrieves the server version from /api/fmc_platform/v1/info/serverversion.fmc_cve2025_20265_checker.py:61-84
• Compares the normalized version against a hardcoded set of affected versions (7.0.7, 7.7.0) and prints a vulnerability warning if matched.fmc_cve2025_20265_checker.py:41-44fmc_cve2025_20265_checker.py:123-124
• Optionally prints a harmless local PoC marker string when a vulnerable version is detected; the marker is never sent to the target.fmc_cve2025_20265_checker.py:46-47fmc_cve2025_20265_checker.py:96-104

Observables

Poc Marker

Payload withheldA static string defined in the script and printed locally when --poc is used; it is never sent to the target. The string resembles a shell command injection payload but is only displayed as a proof-of-concept marker.fmc_cve2025_20265_checker.py:47fmc_cve2025_20265_checker.py:96-104

Classification basis

The code sends crafted authentication requests to trigger a callback (curl to attacker's IP) if the target is vulnerable, but it only observes the callback to confirm vulnerability. It does not deliver a payload or execute arbitrary commands on the target beyond the diagnostic curl. The README describes it as a 'functional exploit' but the code's primary operation is detection and validation, not exploitation.

Requirements

• Target must be a Cisco Secure FMC instance configured for RADIUS authentication.README.md:1
• Attacker must have a publicly reachable IP and open port to receive callbacks.src/main.rs:37-40

Observed behavior

• Performs honeypot detection by checking HTTP redirects, server header, and copyright.src/main.rs:192-250
• Extracts a version hash from the login page to identify the FMC version.src/main.rs:252-267
• Attempts SSH authentication with a crafted password containing a curl command to the attacker's listener.src/main.rs:125-142
• Attempts HTTP authentication with a crafted password containing a curl command to the attacker's listener.src/main.rs:143-158
• Listens for incoming TCP connections and classifies callbacks as SSH or HTTP RCE based on received data.src/main.rs:304-362
• Reports the count of targets and successful RCE checks via SSH and HTTP.src/main.rs:183-186

Observables

Callback Command

Payload withheldThe SSH exploit payload injects a curl command to the attacker's listener to confirm RCE. This is the expected behavior for a PoC demonstrating command injection.src/main.rs:127

Callback Command

Payload withheldThe HTTP exploit payload injects a curl command to the attacker's listener to confirm RCE. This is the expected behavior for a PoC demonstrating command injection.src/main.rs:145

Listener

Payload withheldThe PoC starts a TCP listener to receive callbacks from exploited targets, confirming successful RCE. This is standard for a vulnerability scanner/exploit PoC.src/main.rs:71-75src/main.rs:304-308

External Service

Payload withheldThe PoC queries ifconfig.me to obtain the attacker's public IP if not provided. This is necessary for the callback mechanism and is not a backdoor.src/main.rs:297

Classification basis

The artifact contains a script (exploit.sh) that actively sends a payload designed to trigger command execution on a target. The README confirms it is a simulation demonstrating the impact of CVE-2025-20265, and the script's behavior is to exploit a command injection vulnerability, not merely detect it.

Requirements

• Target server must be running the simulated FMC service on a reachable network port.exploit.sh:3-4

Observed behavior

• Constructs a JSON payload containing a shell command prefixed with 'CMD:' and sends it via HTTP POST to the /api/config endpoint.exploit.sh:5-8
• The default command executed is 'cat /opt/flag.txt', demonstrating arbitrary command execution.exploit.sh:5

Observables

Educational Simulation

Payload withheldEstablishes the intended benign purpose of the code, consistent with the absence of backdoor behavior.README.md:3

Command Execution Mechanism

Payload withheldThis is the normal exploit behavior against the stated target (a local simulation server). It does not exhibit concealed or unrelated harmful actions.exploit.sh:5-8