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Sigma Ransomware


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Yesterday one of our team members received what looked to be a legitimate email from Craigslist, so she opened the attachment and entered the password.  The Sigma Ransomware was deployed.  This looks like the same issue that david0729 is having that Aura is working on with him.  What a crazy thing these criminals do.  I have followed that thread 

All files have been encrypted and cannot be opened.

I don't want to get too far ahead.  So will stop here.  Would love to be able to access our files again.  I have a backup from a few days ago, but only the network files not the local machine files.

Thanks

Rob

 

 

Addition.txt

FRST.txt

malwarebyteslog.txt

Edited by Teachkids
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also went to id-ransomware.malwarehunterteam.com and uploaded the readme.html.  It returned the following:

Sigma

 This ransomware is still under analysis.

Please refer to the appropriate topic for more information. Samples of encrypted files and suspicious files may be needed for continued investigation.

Identified by

 

Click here for more information about Sigma

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Hi Teachkids :)

My name is Aura and I'll be assisting you with your malware issue. Since we'll be working together, you can call me Aura or Yoan, which is my real name, it's up to you! Now that we've broke the ice, I'll just ask you a few things during the time we'll be working together to clean your system and get it back to an operational state.

  • As you'll notice, the logs we are asking for here are quite lenghty, so it's normal for me to not reply exactly after you post them. This is because I need some time to analyse them and then act accordingly. However, I'll always reply within 24 hours, 48 hours at most if something unexpected happens
  • As long as I'm assisting you on Malwarebytes Forums, in this thread, I'll ask you to not seek assistance anywhere else for any issue related to the system we are working on. If you have an issue, question, etc. about your computer, please ask it in this thread and I'll assist you
  • The same principle applies to any modifications you make to your system, I would like you to ask me before you do any manipulations that aren't in the instructions I posted. This is to ensure that we are operating in sync and I know exactly what's happening on your system
  • If you aren't sure about an instruction I'm giving you, ask me about it. This is to ensure that the clean-up process goes without any issue. I'll answer you and even give you more precise instructions/explanations if you need. There's no shame in asking questions here, better be safe than sorry!
  • If you don't reply to your thread within 3 days, I'll bump this thread to let you know that I'm waiting for you. If you don't reply after 5 days, it'll be closed. If you return after that period, you can send me a PM to get it unlocked and we'll continue where we left off;
  • Since malware can work quickly, we want to get rid of them as fast as we can, before they make unknown changes to the system. This being said, I would appreciate if you could reply to this thread within 24 hours of me posting. This way, we'll have a good clean-up rhythm and the chances of complications will be reduced
  • I'm against any form of pirated, illegal and counterfeit software and material. So if you have any installed on your system, I'll ask you to uninstall them right now. You don't have to tell me if you indeed had some or not, I'll give you the benefit of the doubt. Plus, this would be against Malwarebytes Forums's rules
  • In the end, you are the one asking for assistance here. So if you wish to go a different way during the clean-up, like format and reinstall Windows, you are free to do so. I would appreciate you to let me know about it first, and if you need, I can also assist you in the process
  • I would appreciate if you were to stay with me until the end, which means, until I declare your system clean. Just because your system isn't behaving weirdly anymore, or is running better than before, it doesn't mean that the infection is completely gone
    This being said, I have a full time job so sometimes it'll take longer for me to reply to you. Don't worry, you'll be my first priority as soon as I get home and have time to look at your thread


This being said, it's time to clean-up some malware, so let's get started, shall we? :)

Do you have the email your team member received? Can you .zip it and attach it here?

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9 hours ago, Aura said:

Do you have the email your team member received? Can you .zip it and attach it here?

From: Theresa Redfield <983103c36b6e31fd87d23bdc613b28fb@reply.craigslist.org>
Sent: Thursday, March 8, 2018 11:37 PM
To: q5b7p-6490603464@comm.craigslist.org
Subject: Not AV Scanned: Free ACT/SAT Practice Test - general community

Hey

I would like to express my interest in your posting "Free ACT/SAT Practice Test - general community" but I have a few questions.  Please call me ASAP, my contact information are in attachment.

Password to view the file is 5558.

Take care
Kendra


Original craigslist post:
https://bn.craigslist.org/com/6490603464.html
About craigslist mail:
https://craigslist.org/about/help/email-relay
Please flag unwanted messages (spam, scam, other):
https://craigslist.org/mf/65910d29f30fcffa08f943a38cd88bf6606ed2e4.1

 

 

Not_AV_Scanned%3a_Free_ACT%2fSAT_Practice_Test_-_general_community.zip

Edited by Teachkids
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Thank you :)

Sadly as stated by ID-Ransomware, there's still not enough information about Sigma to know if files encrypted by it can be decrypted for free or not. I'll reach out to my colleagues who specializes in Ransomware to see if they have any information about it.

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Yoan,  Thank you for your help.  Would you suggest that I wait to see if one of your colleagues have a solution, go ahead and format the PC/start over, pay the ransom, or take some other action?  Should I make a backup copy of this PC's data in case a key is found in the future or once moved is that worthless?

The computer had 2 mapped drives to a NAS.  Those files are also encrypted, which I have stopped sharing them and have restored to new shares on the NAS (yet maintained those encrypted files).  I am guessing the action you tell me above regarding the PC is the same action to take on the NAS data.

Last, if I reformat the PC, what is the best way to obtain and re-use the Windows Office 2016 key?  I purchased 5 licenses and am struggling to determine which one is assigned to this PC.

Thank you for your help!

Rob

 

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We never recommend paying the ransom, as doing this will only give the authors what they want, contribute to the finance of cybercrime and there's also a chance that they won't even decrypt your files.

The best course of action for the time being (until I hear back from my colleagues at least) would be the leave the computer as is and not touch it (also, leave it open). You should also back up all the encrypted files and store them somewhere safe as well, in case a free decryption solution gets released in the future as you say.

You can use ProduKey for the Office-related issue.

https://www.nirsoft.net/utils/product_cd_key_viewer.html

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Sorry for the delay, I was sure that I replied to your thread yesterday.

I spoke with one of my colleage, and as far as she knows, there's no way to decrypt the files encrypted by Sigma for free at the moment. The best thing you can do, is restore these from a back up, and back up the encrypted files and store them somewhere safe, in a hope that one day a free decryption solution for Sigma will be released.

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Due to the lack of feedback, this topic is closed to prevent others from posting here.

If you need this topic reopened, please send a Private Message to any one of the moderating team members. Please include a link to this topic with your request.

This applies only to the originator of this topic. Other members who need assistance please start your own topic in a new thread.

Thanks

 

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