[Investigation Request] Hacker's Modus Operandi

PSA: Recently came across a post in r/ledgerwallet on a user being hacked. But no one knows for sure how it was done. Here's the link: https://np.reddit.com/r/ledgerwallet/comments/1aonk6r/1eth_stolen_from_ledger/

Can someone help to decipher this hacker's way of stealing funds from wallets?

Hacker's address: 0xdf05a927799d906d81a3b238c8cf60fa12518a84

After analyzing the address, it may be due to one of the causes (or a mix of it) below.

1. Phishing Attack (seed phrase leaked to hacker);
2. Smart Contract vulnerability (i.e. "SetApprovalForAll" function);
3. Private key was generated by the hacker himself and was given to the user without the user realizing it.

Curious to know what are your thoughts.