Hot answers tagged

128

Hibernate the computer If the ransomware is encrypting the files, the key it is using for encryption is somewhere in memory. It would be preferable to get a memory dump, but you are unlikely to have the appropriate hardware for that readily available. Dumping just the right process should also work, but finding out which one may not be trivial (eg. the ...


58

This 2013 article analyses retention time for several DRAM chips. Among the relevant information, one may list the following: Retention time depends on a lot of things, including the values of neighbouring bits. A DRAM bit is a potential well, and it loses its contents by moving charges from or into neighbouring areas, so whether there is room in these ...


53

What I would do: Suspend the proces. Don't kill it, just pause it. Look in the process tree if there are any parents that might need suspending as well. Pull the network cable and/or turn off WiFi (and if you're paranoid, Bluetooth too). Check open files by those processes to see which one it is currently encrypting. If it's a particularly important one, ...


51

Ransom-ware (or any encryption software for that matter) will not encrypt the file in-place, because the encrypted filesize will not match the unencrypted filesize bit-for-bit (unless it's just an xor shuffle, in which case it's not really encryption). More importantly, a spontaneous abortion of the encryption process (due to a shutdown, running out of ...


18

The reason you write '0' instead of '1' has to do with the way magnetic storage encodes the 0 and the 1. a long explanation of it can be found on Wikipedia under Run-length_limited. In short RLL is the methodology used to store the '1' and '0' and it is more complex than just to store the bit values themselves. On a side note to make the drive more like it ...


17

There are mechanisms that could result in data remanence in DRAM beyond the charge stored in the gates (which is typically gone in seconds, especially at normal elevated operating temperature). One is movement of ionic contaminants which can cause slight shifts in thresholds. This could be the 'burn in' that Tom's answer refers to. There may not be any ...


11

There are any number of different ways it can be done. In large part, the easiest way is following the link pointers to each of the chunks, but that isn't the only way by any means. (The MFT isn't the only source of those links in many file systems as well.) At a lower level, it can identify all the chunks and try to match some of them up on content if the ...


10

This is enough, or not, depending on the disk technology, the budget of the attacker, and some other details. When you fill a disk with zeros, you force the filesystem to reuse free blocks, and rewrite them. So, as first order approximation, this looks good for you: your file contents are overwritten. However, there are details: On some operating systems ...


10

It is not possible to create a digital communication that will self-destruct after a certain amount of time (or upon sender's command). This because of the nature of the message, which once reaches the recipient' machine can be copied at will. This applies to email as well as instant messages. Therefore any service promising you messages that ...


10

Factory resets reset your phone to a stock like state but does not remove your data, just applications. This leaves some data behind. The best way to prevent this data from being recovered is to encrypt the phone, and use wipe data/factory reset from the recovery menu. This way you don't have to download a ton of data and you can be fairly certain your ...


10

I feel like random people on the internet are not going to be able to answer this for you. This is a business decision. How valuable is the data? What is the risk of loss / corruption vs the cost of more disk space? Imagine your worst disaster-recovery scenario, how far back would you need to go to get a clean snapshot? I certainly can't answer any of this ...


9

Unlikely. It's AES-CBC-128, so there's no chance of you cracking the key. There are a few tools (e.g. Volatility, or Elcomsoft's forensics suite) that can recover the master key from a system memory dump, but that only works if the drive is already mounted and unlocked.


9

There are a few ways to solve this situation. One is to have the camera always encrypt one of the session keys to a camera backup key. The camera backup key is generated on account setup of the camera and a password is generated that is used to encrypt the backup key. This password is never stored on the camera itself. Your online storage would store the ...


9

As a former developer for one of the biggest Security Card System organizations in the world, I can confirm with you that the answer is resounding YES depending on the manufacturer and the type of the card. For example, my company used the standard ISO encoding standard for magnetic stripes for Debit cards, and quite frankly there is not much confidential ...


8

How does the Recycle Bin work? When you delete a file from a hard drive the file is moved to a folder named $Recycle.Bin on the same drive. So when you delete the file D:\Work_Files\SuperWeirdPr0n.mp4 it's actually moved to D:\$Recycle.Bin. The main Recycle Bin "folder" is actually just the aggregation of the content from all $Recycle.Bin folders from all ...


8

The best citation I can give is from Overwriting Hard Drive Data: The Great Wiping Controversy, which was published as part of the 4th International Conference on Information Systems Security, ICISS 2008. You can view the full text of the paper by viewing the book on Google Books, and jumping to page 243. The following excerpt is from their conclusion: ...


8

Usually Factory Reset is probably enough for removing almost all data stored internally by the Android phone. Menu> Settings> Privacy> Factory data reset> Erase phone storage Un-tick backup if not necessary. To be double sure(Extra paranoid mode): Do the Factory reset and then Menu> Settings> Security> Encrypt phone> Encrypt ...


7

What you describe is the worst possible practice possible apart from just handing it over. From a security standpoint it poses significant risks to both the previous and current parties. The easiest way to reformat PCs is to use what is called a "golden image" this image is a windows image you: keep up to date only install the bare minimum of programs ...


7

If you use sdelete from Microsoft (http://technet.microsoft.com/en-us/sysinternals/bb897443.aspx) you don't have to install anything. It has an option to fill the unused disk space with zeroes too. If you already deleted the files this is what I'd just to make sure that nothing remains of the original file.


7

Did a test with three different cards. Card 1 (Non-Chipped MC Pre-Paid) Swiped the card through a USB Magtek MSR Reader, and noted results. Got a clean Track 1 and Track 2 data. Cut the card vertically straight down the middle into a left piece and right piece. Took each piece and tried swiping through the card reader. Would only get an %E?;E? which ...


7

Short answer: That won't work. You'll need to degauss it, which will render the drive unusable. Long answer: Sure. Get a powerful magnet, put it next to the hard drive, with N facing the drive. Then flip it around so S faces the drive. Then flip it again, then again. Do this a few thousand times a second. If you do it any slower or just put it near the ...


7

In addition to the shutdown & copy approach others have mentioned there's another factor: The ransomware wants to hide what's going on until it's finished it's evil--thus the encrypted files are usually still readable as if they weren't encrypted until it's ready to demand it's ransom. Once you have located the files that matter and are encrypted put ...


6

First check with your legal expert if there are any laws in your country which require you to have a minimum retention period. For instance depending on your industry you might have to take into account either of these regulations: Sarbanes-Oxley regulations: To comply with SOX guidelines, companies must retain auditable emails for a minimum of five years ...


6

In theory any device can store anything, because it is speced to meet an interface, not spec'd for its implementation. Realistically speaking, the answer is more murky. This, by the way, is where SSD's get so interesting because there is no accepted way to tell a SATA SSD to "wipe everything" (edit: no way that is reliably trustworthy, at least) From ...


6

The best cryptographers use cryptography only when necessary. That being said, this proposed design is needlessly complex. Your design incorporates two different hash functions, symmetric and asymmetric encryption. Further more you make no mention of what attacks you are trying prevent, which leads to a superstitious design that is difficult to ...


6

Could malware interfere with the wiping process? If there is malware present on the system, then yes, it will be able to interfere with the memory wiping process. If a malicious process spawns many copies of itself in memory, it can prevent the processes which initiate memory wiping from executing, essentially causing the computer to hang. This is an ...


5

The virtual machine usually stores its virtual hard disk as a normal file on the host operating system's filesystem. Think of a filesystem like a warehouse. The warehouse contains a large number of boxes (files) and a manifest that lists all of the boxes (the file table). When you delete a file, it doesn't actually destroy the data, it just deletes the ...


5

A forensic tool such as FTK imager, is essentially a binary data reader and interpreter. Oversimplified, it reads each value and shows you both the hexidecimal (or decimal) absolute value and/or the interpreted value (such as text). Google for more examples and explanations of how FTK imager works. Notice that a forensic toolkit is merely a tool. Most ...


5

In NTFS, all of the metadata is stored in the MFT. This includes names, dates, parent folder, etc. the occupied clusters are also stored in there in a structure called data runs. The clusters storing the file data hold only file data and there is no linked list that holds info about the next or previous cluster. When a file is deleted (assuming a skip of ...



Only top voted, non community-wiki answers of a minimum length are eligible