CVE-2021-33315
📋 TL;DR
CVE-2021-33315 is a critical integer underflow vulnerability in TRENDnet TI-PG1284i switches that allows remote attackers to trigger buffer overflow or invalid memory access via crafted LLDP packets. This affects TRENDnet TI-PG1284i hardware version 2.0R switches running firmware versions prior to 2.0.2.S0. Attackers can potentially execute arbitrary code or crash the device.
💻 Affected Systems
- TRENDnet TI-PG1284i
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, network disruption, or lateral movement within the network.
Likely Case
Device crash causing network outage, denial of service affecting connected devices.
If Mitigated
Limited impact if network segmentation prevents LLDP packet access to vulnerable switches.
🎯 Exploit Status
Exploitation requires sending specially crafted LLDP packets to the vulnerable switch.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.0.2.S0
Vendor Advisory: https://www.trendnet.com/support/view.asp?cat=4&id=81
Restart Required: Yes
Instructions:
1. Download firmware version 2.0.2.S0 from TRENDnet support site. 2. Log into switch web interface. 3. Navigate to System > Firmware Upgrade. 4. Upload and apply the new firmware. 5. Reboot the switch.
🔧 Temporary Workarounds
Disable LLDP
allDisable Link Layer Discovery Protocol to prevent exploitation via crafted packets.
configure terminal
no lldp run
end
write memory
Network Segmentation
allIsolate vulnerable switches from untrusted networks using VLANs or firewalls.
🧯 If You Can't Patch
- Implement strict network access controls to limit LLDP traffic to trusted sources only.
- Monitor network traffic for anomalous LLDP packets and implement intrusion detection.
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface: System > Firmware Information. If version is below 2.0.2.S0, device is vulnerable.Check Version:
show version (via CLI) or check web interface System > Firmware InformationVerify Fix Applied:
After patching, verify firmware version shows 2.0.2.S0 and test LLDP functionality if required.📡 Detection & Monitoring
Log Indicators:
- Switch crash logs
- LLDP protocol errors
- Memory access violation logs
Network Indicators:
- Unusual LLDP packets with malformed PortID TLV fields
- LLDP traffic from unexpected sources
SIEM Query:
source="switch_logs" AND ("crash" OR "lldp error" OR "memory violation")