Is SMB safe enough for remote access using my credentials over an untrusted network?

Question

I have a Windows (8 Consumer Preview) PC and a Macbook (OS X Lion). Sometimes, I'd want to pause working on a project leave my Windows PC at my room connected to my college's intranet, and keep working somewhere else (in the campus) with the same files, and I don't want the hassle of carrying a USB/uploading to FTP/waiting Dropbox to sync big files etc. so I just want direct access to my project files over the network. However, I'm concerned about the safety of this approach. I've set the sharing settings to my workspace's directory such as: my own account (that I use to log onto my PC) has full access to the files, and I've removed all the permissions (including list dir and read) from the Everyone "user". I can SMB-connect to my PC over the network successfully with my PC credentials and it works perfectly, but is my data (including BOTH my files and my credentials) safe from eavesdropping. The network is completely unsecure (unsecured regular WiFi, just as in a coffee shop) and I need to rely on the safety at a higher layer. Is there any? If not, are there any alternatives (given my requirement previously)?

Thanks, Can.

Solution

The LM and NTLM algorithms have been broken many times. Only NTLMv2 (if the server enforces its usage) is strong enough against casual sniffers, but it can be broken quickly by a bruteforce attack.

However, regardless of which authentication method you use, the SMB protocol doesn't support encryption and will transfer your files in plain text, so it is not recommended to use over public Internet except through a VPN.

An alternative is SFTP, the SSH file transfer protocol. There are several SSH servers for Windows (I prefer Bitvise WinSSHd), and many SFTP clients for both Windows (WinSCP) and OS X (if I recall correctly – Transmit, Cyberduck, OSXFUSE).

Comments

[Scott Chamberlain]

Not enough to to write up a full answer but I also wanted to mention FTPS (Ftp over SSL) This is implemented in FileZilla and I am sure many others.

[user1686]

For me, SFTP has also been much faster than SMB; transferring files at 7 MB/s over 100Mbit LAN while SMB could only reach 2 MB/s. (I could not test with Win7/8, however, which support an allegedly much improved SMBv2 protocol.)

[Ashley]

As introduced with Windows 8, SMB 3.0 now includes encryption, and Samba supports it. You can force it by setting client/server min protocol = SMB3