[hibbelig]

I recall a story here on HN, some days ago. A company was attacked, then the attackers waited some months to make sure that all backups had been contaminated, then they struck.

So victims can only make sure that they have a malware checker that finds the culprit, then do fresh installs, then check each file before it's restored from backup. Sounds like a crazy amount of work.

[andreareina]

Immutable append-only backups would protect against this, right? Nuke the OS to make sure you're running on good software, then pull in data that's as good as it was when it was backed up.

[hibbelig]

The old backups are clean, yes. But newer backups (created after infiltration) will be contaminated. Immutable and append-only doesn't help because the files were already contaminated when backed up.

The attacker could: get the victim infested with malware; ensure that the malware infects all new files; wait one year; then trigger the encrypt function.

If the victim pulls a file that is newer than one year old from backup, the victim will pull the malware from backup.

(Only if the file is of a type that could be infected in the first place, of course. README.txt will not be infected.)

[danielheath]

Only to the degree that attackers can't figure out a way around them (given months of planning with access to internal systems & documentation).

For instance: I have backups going to an append-only s3 bucket in a separate AWS account, but I don't have monitoring in place to ensure that bucket hasn't been wiped. An email would get generated, but it'd go to the root account holder, who may not notice in time.

[andreskytt]

Kinda makes me wish for the good old days when you could just store a pile of tape

[nix23]

Good old Days? There is a reason Financial Institutes still uses WORM tapes, and they are great!