OpenWrt & WiFi Exploitation
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Installation & Switching back to vendor firmware
🔗 OpenWrt
TP-Link EAP225 v2
TP-Link
EAP225
v2
22.03.3
EAP225
v2
Qualcomm Atheros QCA9563
775
16
128
Qualcomm Atheros QCA9563, Qualcomm Atheros QCA9882
b/g/n
a/n/ac
Firmware Download
EAP225
v2
22.03.3
📝 Notes:
SSH client must support RSA keys ⇐1024 bits in length. See workaround below.
v2 uses same factory image as v1
<DEVICE-IP>= EAP225 Lan IP
Enable SSH access if you haven't already done so
Exploit a command injection vulnerability in the user management page of the web interface to start telnetd by changing the username to
;/usr/sbin/telnetd -l/bin/sh&
Immediately change the malformed username back to something valid (e.g. 'admin') to make ssh work again.
Use telnet to connect to your router (telnet ${device-ip}) and issue chmod 777 /tmp to make it writable
Extract /usr/bin/uclited from the device via ssh:
Create a copy of the file so that the patch can be applied later:
Check if the md5sum matches 4bd74183c23859c897ed77e8566b84de:
Apply the binary patch to uclited:
Check if the md5sum matches 4107104024a2e0aeaf6395ed30adccae:
Copy the patched uclited binary back to the device at /tmp/uclited:
Upload the factory image to /tmp/upgrade.bin:
Copy openwrt-22.03.3-ath79-generic-tplink_eap225-v1-squashfs-factory.bin to %USERPROFILE%\Documents\MobaXterm\home
Finally, install OpenWrt (via the telnet session): chmod +x /tmp/uclited && /tmp/uclited -u
✅ Success! - OpenWrt 22.03.3
New Default IP: 192.168.1.1.
SSH into it and set a static IP from the LAN network + Gateway + DNS.
Workaround for SSH key length (NOT USED with MobaXTerm)
The SSH server (dropbear) on the factory image uses weak crypto algorithms and short key length. Openssh clients distributed with most modern Linux distributions do not support this by default. Here are some options to workaround this:
Use alternative SSH client:
openssh-client-ssh1packageUpdate the host key length:
telnet to the router
run command
/usr/local/sbin/dropbearkey -t rsa -f /tmp/dropbear_rsa_host_key2 -s 2048kill currently running dropbear process
run command
/usr/local/sbin/dropbear -p 22 -r /tmp/dropbear_rsa_host_key2 -d /tmp/dropbear_dss_host_key -Lnow you should be able to SSH using the ssh commands supplied
🔗 Links
📌 For experienced users only!
This HOWTO will upgrade an existing OpenWrt firmware to a new version from the SSH command line.
Back up OpenWrt configuration
Download and verify the OpenWrt firmware upgrade imageDownload and use only OpenWrt firmware images ending in “-sysupgrade.bin” for command line upgrades. For x86 systems there is no “sysupgrade” image, just be sure the new firmware image has the same family of filesystem as your old one.
📌 Note: upgrade files must be placed in /tmp, as the sysupgrade procedure unmounts flash storage during the upgrade process. If the upgrade file is not in /tmp, sysupgrade will NOT perform any upgrade and only reboot the system.
Check free memory is available: Run
free. Proceed, if “free Mem” is the size of your firmware file + some extra mem (at least twice the size of your firmware file is perfect).Set the following variables to the download address of your OpenWrt firmware file (you must customize the URL!). You'll find a link to the file “sha256sums” in the Supplementary Files section of the download page for the architecture of your router, beneath the Image Files section:
Download and check the firmware checksum with:
In the screen output, look for the correct checksum verification:
Do not continue, if the checksum verification mismatches!
Troubleshooting:
If you cant use 'wget' (e.g. because you want to transfer firmware from your PC to your OpenWrt device)
you can use scp:
scp openwrt-ar71xx-tl-wr1043nd-v1-squashfs-sysupgrade.bin root@192.168.1.1:/tmp(Ensure you have set a non-null password for your device root account to properly use scp.)you can use ssh:
ssh root@192.168.1.1 “cat > /tmp/openwrt-ar71xx-tl-wr1043nd-v1-squashfs-sysupgrade.bin” < openwrt-ar71xx-tl-wr1043nd-v1-squashfs-sysupgrade.bin(Also ensure you have set a non-null password for your device root account.)you can also use nc/netcat:
On your Linux PC run:
cat [specified firmware].bin | pv -b | nc -l -p 3333On your OpenWrt device run (Assuming 192.168.1.111 is the IP of your Linux PC):
nc 192.168.1.111 3333 > /tmp/[specified firmware].binCommand-line instructions
Troubleshooting:
If you get the error
ash: /usr/libexec/sftp-server: not foundfor the scp command, you are using an OpenSSH Release >= 9 which defaults to using sftp which is not installed by default on OpenWRT. To fallback to the legacy scp/rcp, use the -O flag:scp -O firmware_image.bin root@openwrt.lan:/tmp.If sysupgrade is not available.
The sysupgrade verbose-option should give some output similar to this. The list of configuration files saved will change depending on what packages you have installed and which files you have configured to be saved, as per above.
Note: The “TRX header not found” and “Error fixing up TRX header” errors are not a problem as per OpenWrt developer jow's post at https://dev.openwrt.org/ticket/8623
Wait until the router comes back online
After the automatic reboot, the system should come up the same configuration settings as before: the same network IP addresses, same SSH password, etc.
Proceed to the “Additional configuration after an OpenWrt upgrade” section, below
Troubleshooting
Flash the new OpenWrt firmware
The firmware file is now in /tmp, so you can start the flashing process
Preferably have an assistant physically present at the location of the device, if you upgrade it from remote (as some devices may require a hard reset after the update)
Execute the following command to upgrade:
You can add the
-noption if you DO NOT want to preserve any old configuration files and configure upgraded device from clean state (network/system settings will be lost as well)While the new firmware gets flashed, an output similar to the following will be shown:
Ignore the “TRX header not found” and “Error fixing up TRX header” errors. These errors are not relevant according to https://dev.openwrt.org/ticket/8623
Wait until the router comes back online. The system should come up the same configuration settings as before (same network IP addresses, same SSH password, etc.)
Troubleshooting:
OPKG issues: if after flashing you have issues with package installation or because opkg.conf has outdated data, read https://dev.openwrt.org/ticket/13309
'sysupgrade' not available on your OpenWrt device, you can use 'mtd' instead to flash the firmware:
mtd -r write /tmp/openwrt-ar71xx-generic-wzr-hp-ag300h-squashfs-sysupgrade.bin firmware
Post-upgrade steps
Verify the new OS version: The simpler way to see if the firmware was actually upgraded. In SSH, the login banner states the release information like version and so on.
Reinstall user-installed packages. After a successful upgrade, you will need to reinstall all previously installed packages according to your notes. Package configuration files should have been preserved due to steps above, but not the actual packages themselves. If you used the scripts provided in the forum, this step might not be necessary.
Comparing new package config options
The new package installations will have installed new, default versions of package configuration files. As your existing configuration files were already in place, opkg would have displayed a warning about this and saved the new configuration file versions under
*-opkgfilenames.The new package-provided configuration files should be compared with your older customized files to merge in any new options or changes of syntax in these files. The
difftool is helpful for this.Low memory workarounds: /tmp is too small to hold the downloaded file
If your device's /tmp filesystem is not large enough to store the OpenWrt upgrade image, this section provides tips to temporarily free up RAM.
First check memory usage with the
freeortoporcat /proc/meminfocommands; proceed if you have as much free RAM as the image is in size plus an some additional MiB of free memory.In this example there are precisely 11416 KiB of RAM unused. All the rest 32768 - 11416 = 21352 KiB are used somehow and a portion of it can and will be made available by the kernel, if it be needed, the problem is, we do not know how much exactly that is. Make sure enough is available. Free space in /tmp also counts towards free memory. Therefore with:
One has actually 752+6636 KiB of free memory available.
quickest and safest way to free up, some RAM is to delete the package lists:
drop caches:
prevent wireless drivers to be loaded at next boot and then reboot:
The wireless drivers usually take up quite some amount of RAM and are not required if you are connected by wire. You can delete the relevant symlinks in
etc/modules.dand reboot to free up the RAM.Still no room in /tmp?
Flash using ssh
Flash using netcat
Your device must already have an older OpenWrt firmware installed, to be eligible for this “sysupgrade” procedure.
Back up OpenWrt configuration
Locate and download the OpenWrt firmware
Download the sysupgrade file. Please note that not all devices do have a firmware image called sysupgrade.bin.
Troubleshooting:
Some devices lack a sysupgrade image and require a special (and usually a bit more complex) installation procedure that is device-specific. This tutorial won't apply for such devices. Instead follow the custom installation description on the corresponding device page in the OpenWrt wiki.
If you have accidentally browsed the generic OpenWrt download folders to locate your device, you might see some more download files matching your device.
Verify firmware file and flash the firmware
Connect to the device via Ethernet cable (Only use wireless if the device has no Ethernet connection options)
Log into the web interface and in the System → Backup/Flash Firmware menu, go to the “Flash new firmware image” section.
Ensure that the OpenWrt firmware file you are about to flash matches your router model and is called “....sysupgrade.bin” (the file type varies like .bin .tar.gz etc., but the key is “sysupgrade”), as you will upgrade an existing OpenWrt system towards a newer OpenWrt firmware version.
In the “Flash new firmware image” section, click “Choose file” to select the image file, then click “Flash image...”. This displays a “Flash Firmware - Verify“ page, containing a SHA256 checksum of the image file just uploaded to the router.
If the checksum matches, click “Proceed”. This starts the “System - Flashing ...” along with a spinning wheel and “Waiting for changes to be applied...”
It can take several minutes, while the router uploads the firmware image and write it into its flash ROM and finally reboots.
The new firmware has been installed. Continue with the next section to check the result.
Troubleshooting:
if the checksum process failed, do NOT start flashing, as the download could be corrupt. A corrupt firmware file can brick your device! Instead repeat this howto with another download attempt from the download section.
Post-upgrade steps
After your device has finished flashing and rebooting, check if you can access the LuCI web interface (or the IP that you know of).
Troubleshooting:
A fully offensive framework to the 802.11 networks and protocols with different types of attacks for WPA/WPA2 and WEP, automated hash cracking, and much more.
Attacks
Deauthentication Attack
Authentication Attack
Beacon Flood Attack
PMKID Attack
EvilTwin Attack
Passive/Stealthy Attack
Pixie Dust Attack
Null Pin Attack
WEP Protocol Attacks
Michael Exploitation Attack
Features
WPA/WPA2, WPS and WEP Attacks
Auto handshake capture and cracking
Multiple templates for EvilTwin attack (even custom)
Check monitor mode and its status
2.4Ghz and 5Ghz attacks
Descriptive attack logs (just done user side)
Custom wordlist selector
...
is ok.
Upgrade the firmware to version (that's a strict requirement for the patch to work!)
A lot of information in this wiki page duplicates content of .
Non-experienced users are strongly advised to instead.
If you need some configuration options changed for the first boot, for example you need Wi-Fi enabled after flashing, follow .
Follow , or skip this section if you do not want to preserve existing configuration.
Download the desired upgrade file to your OpenWrt's /tmp directory and . /tmp directory is stored in the device RAM:
If the checksum mismatches: Redo the firmware download, if the mismatch remains, ask for help in the
If low on RAM see:
OpenWrt provides utility for firmware upgrade procedure.
firmware image checksum. Verify the router has enough free RAM. Upload the firmware from local PC. Flash the firmware.
In case it does not help, try a (= interrupt the electrical current to the device, wait a couple of seconds and then connect it again). Be careful about /etc/opkg.conf as explained . For unknown reasons such a cold reset has often been reported to be necessary after a sysupgrade. This is very very bad in case you performed this remotely.
does not reboot automatically or remains unresponsive: Wait 5 minutes, then do a hard reset: Turn it off, wait 2-3 seconds and turn it back on (or pull the power plug and plug it back in). Doing this while the device is still updating might softbrick it and require serial or even jtag connection to recover it. Such a cold restart has been reported to be required often after a sysupgrade by command line.
If you used extroot, then see about restoring it.
Check for any . After the firmware update, it is good to check for any updated packages released after the base OS firmware image was built.
See also: ,
Use only if you really cannot free enough RAM with other means. Any network issues during the process are likely to brick your device.
Alternatively refer to the howto, to install OpenWrt on a device that still has vendor factory firmware on it.
If your current OpenWrt installation does not have web interface installed or if you prefer to upgrade from the command line (upgrade from command line provides more fine-grained control), refer to .
If you have any questions about this description, ask for help on the before beginning.
Be aware of major config and version compatibility.
Follow , or skip this section if you do not want to preserve existing configuration.
On the page, locate your specific device.
If you don't find your device in the Table of Hardware or Device Pages/Techdata pages, you can also try
Uncheck/clear the “Keep settings” checkbox especially for major version upgrades, so that new defaults will get applied. Keeping settings may be possible for minor upgrades, but there is always a risk of incompatible settings. (more info regarding the and its use cases).
that the firmware-checksum displayed in web interface matches the SHA256 checksum from the OpenWrt download page. If it does not match, do NOT continue, as it is a corrupt file and will likely brick your device. Note: If you are upgrading from OpenWrt 15.05, the 32 character displayed is an MD5 checksum, not SHA256. Please verify this MD5 checksum on your operating system before proceeding.
if the checksum step fails repeatedly, you can consult the for help. Be sure to include the exact brand, model, and version of your device.
See Post-upgrade steps in
If you have flashed a development/snapshot firmware of OpenWrt, you first need to manually enable the web interface: . Or verify the result by SSH-connecting to your OpenWrt device.
The router may have succeeded, but gotten a different IP address than you expected. Either scan your local network, check your regular router's status page (to find out about the IP address it has assigned to your OpenWrt device) or use , to manually reset OpenWrt's settings (which includes the network settings)
If you have checkmarked the “Keep settings” checkbox in the previous section and the system fails to boot after flashing, you need to consult the , to manually reset all settings.
Otherwise you need to start configuring from scratch. In this case, remember to properly set your country code in the OpenWrt Wi-Fi configuration again, to comply with your country's Wi-Fi legal regulation, e.g. see in .
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