W3.7z

| Use Case | Command | Ratio | Speed | |----------|---------|-------|-------| | Daily backup (fast) | 7za a -mx=3 -ms=on W3.7z ./source/ | 65% | High | | Archival (smallest) | 7za a -mx=9 -md=256m -mfb=273 -ms=on W3.7z ./ | 95% | Very low | | Blockchain snapshot | 7za a -mx=7 -mqs=on -mmt=12 W3.7z ./chaindata/ | 82% | Medium |

If you see files ending in .w3x or .w3m, this is a custom map. | Use Case | Command | Ratio |

7za a -p"YourStrongPassword" -mhe=on -mx=9 W3.7z /path/to/folder

Sometimes, .7z files act as disk images. 7za a -p"YourStrongPassword" -mhe=on -mx=9 W3

Weak passwords on W3.7z files (e.g., password123) can be cracked using hashcat with mode 11600 (7-Zip).
Defense: Use 20+ character random passwords; store in a vault like HashiCorp Vault. Sometimes,

A malicious W3.7z might contain entries like ../../etc/shadow. By default, 7-Zip sanitizes paths, but older versions (pre-16.04) were vulnerable.
Defense: Update to 7-Zip 22.01 or later.