Backups and encrypto virus6/23/2023 But don’t take an anonymous voice as your only opinion. If you do incremental or differential backups, you’ll also note that the size of the backup files suddenly gets really huge, as the amount of changed files/sectors is suddenly much larger than expected. It can’t be that easy to defeat the time bomb, can it? So those things could be used to rescue the data from the restored (encrypted) hard drive, if my guess is correct. It would stand to reason that, strategically, the malware would not attempt to intercept these things, or even file copy operations to a USB stick, to avoid advertising its presence too early. That would be a dead giveaway that something was wrong, and the time bomb would be ruined. But what if the data were to be written to an FTP server or network share (on an uninfected machine, perhaps one not running the same OS), or emailed to someone? These kinds of things would be quite common occurrences in business settings, I would think, and if the malware (still in the lie and wait phase) tried to encrypt the data being sent to a machine not able to decrypt it on the fly, not only would that require a big step up in sophistication on the part of the malware to get into the network stack, but it would also signal its presence, as the the recipient of the file (which could not be encrypted transparently at the disk level, as the recipient machine would be clean) would notice it was scrambled. I would expect that at this point, if the user (who by this point was fully aware that ransomware was present, as it would have already demanded payment) attempted to file-copy the important files (which would be decrypted as they were read into the copy buffer), the malware would attempt to re-encrypt the newly written file as it was written to another fixed disk on that system. when the malware was still in its waiting stage. The question I have, though, is if the backup is restored while the PC has no internet access, and the RTC date is set to, say, the moment the backup was started (the same time and date that would be reflected in the shadow copy), how would the malware know to pull out the key? The PC could quite easily be restored to the exact state it was in when the backup was performed, i.e. The idea would be that it would hide its presence long enough to allow the non-encrypted versions to eventually be removed from the backup chain. It would have to silently encrypt the data on the disk, but also decrypt it on the fly for the unsuspecting user, so that the presence of the malware is not advertised. It would not wait until the time is up before encrypting everything, though, as that can take hours and hours on a large disk, giving the victims the chance to interrupt it. In order to deliver the time bomb, the malware would have to disguise its presence during the latency period. Yes, non-executable files being “infected with ransomware” means that the files on disk must be encrypted already and depend on the ransomware driver to be transparently opened between then and the trigger date. This reply was modified 3 years, 8 months ago by Vincenzo. When you plug it in again, after the bomb date, the files get encrypted.) (No, nothing happens when it is unplugged. The malware used to launch the attack will infect data, including all the backups, for months before encrypting all that data. Now it’s been observed that ransomware is being launched as a form of an advanced persistent threat. Plant a ransomware time bomb: When ransomware encrypts data, the encryption it generally does so as soon as or shortly after it gets onto the corporate network. So, to be sure, should verify that the backup device is readable on another computer. What is possible with a suitable device driver is that the encryption happens right away, but initially is keyed to open transparently. Well unless it’s just the data line that’s unplugged AND the thing is a NAS or something with its own operating system or some such and it’s the latter that’s infected with the ransomware. But even so, i’ve read that some ransomware could put a time bomb in, such that the encryption does not happen right away, which could defeat even that.Įh? An unplugged drive cannot change its contents. My backup drive is unplugged when not running.
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