20,000 Open Doors: Analyzing the BRIDGE:BREAK CVEs in Silex/Lantronix Gateways
Just saw the Forescout report on BRIDGE:BREAK, and it’s a stark reminder that the weakest link in OT is often the bridge itself. We're looking at 22 new vulnerabilities (CVE-2024-38999, CVE-2024-39000, CVE-2024-39371, etc.) affecting Lantronix PremierWave and Silex SX-300/500 series devices.
These serial-to-Ethernet converters are everywhere—connecting legacy HVAC, UPS systems, and industrial controllers to corporate networks. The flaws range from authentication bypasses (CWE-287) to buffer overflows (CWE-119) that allow full RCE. What's terrifying is that Vedere Labs found nearly 20,000 of these exposed directly to the internet.
For those trying to asset tag these, you can identify them by their specific web server headers. Here is a quick Python snippet to scan a local subnet for the default management interface headers:
import requests
subnets = ['192.168.1.0/24'] # Add your subnets here
common_ports = [80, 443, 280]
# Note: Requires ipaddress module or external tool for subnet iteration
# This is a basic example check for specific targets
targets = ['192.168.1.50', '192.168.1.100']
for ip in targets:
for port in common_ports:
try:
url = f"http://{ip}:{port}"
r = requests.get(url, timeout=2)
server_header = r.headers.get('Server', '')
if 'Lantronix' in server_header or 'Silex' in server_header:
print(f"[+] {url} - Vulnerable Gateway Detected")
except requests.RequestException:
continue
Most of these devices don't support auto-updates, so patching is going to be a manual slog. Are you guys segmenting these into isolated VLANs, or just trying to firewall the management ports and hope for the best?
We use Censys and Shodan queries internally to catch these before the bad guys do. A simple query like http.server:"Lantronix" or http.title:"Silex Technology" reveals just how many organizations leave these hanging. The mitigation strategy has to be segmentation; you can't trust the firmware update cadence on these legacy boxes. We pushed a policy to block all inbound traffic to TCP 280 and 443 on these specific MAC OUI prefixes.
I tested the auth bypass on a lab unit for PremierWave. It's trivial—no credentials required for the config endpoint. Once you're in, you can re-route the serial data to a rogue server. If these are connected to something critical like a UPS or a PLC relay, an attacker could cause physical damage without ever touching the core SCADA host. Update your inventory lists, folks.
Patching is a nightmare. We have some old Lantronix units that are EOL and don't have firmware fixes for these CVEs. We're effectively forced to put a strict ACL in front of them and replace them with modern gateways as budget allows. It feels like whack-a-mole with serial-to-IP gear.
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