The Locky ransomware has got a slightly updated look and feel, the new variant appending the .aesir extension and creating -INSTRUCTION.html ransom notes.
A fresh edition of the Locky file-encrypting ransomware lineage has been discovered. While sharing a lot of the characteristics with its predecessor known as Thor, the pest in question is undoubtedly a standalone sub-version accommodating a number of unique properties. The infection concatenates the .aesir extension to encrypted files, so the .thor string is now history as far as new contamination incidents are concerned. Another alteration is that the malady adds a recovery help file named _[random_number]-INSTRUCTION.html. Furthermore, the Aesir virus uses a BMP counterpart of this manual as the desktop background. Unlike the previous build, the C2 server used for this particularly campaign now resolves to “/information.cgi”.
The Aesir persona of Locky still targets widespread formats of data on computers that it infects. Moreover, it’s not only the information on static hard disk that’s subject to this adverse effect. The ransomware also traverses removable and cloud drives in search of personal files. Once the data lookup has been completed, the perpetrating program will utilize a combo of AES-128 and RSA-2048 cryptosystems to deny the accessibility of all potentially important files. So it’s double trouble in terms of the fix. The above-mentioned desktop wallpaper reflects the mishap quite accurately. The Trojan also badly changes the filenames. It replaces them with random 32-character strings and subjoins the .aesir extension to each one. Here’s an example of what a regular item ultimately turns into: C1CEA3A2-1F64-CC97-2D81-7A075074EB01.aesir.
As before, Aesir instructs the victim to install the Tor browser and use it to visit the Locky Decryptor page. This anonymous resource is intended to inform the plagued user about the size of the ransom and the Bitcoin address for this payment. It also provides the automatic decryption tool that becomes downloadable after the buyout transaction is verified on the other end. Most of the black hat affiliates distributing Locky request 0.5 BTC, which is currently about 360 USD. The amount may vary, though.
Aesir ransomware automated removal and data recovery
Owing to an up-to-date database of malware signatures and intelligent behavioral detection, the recommended software can quickly locate the infection, eradicate it and remediate all harmful changes. So go ahead and do the following:
1. Download and install the antimalware tool. Open the solution and have it check your PC for PUPs and other types of malicious software by clicking the Start Computer Scan button
2. Rest assured the scan report will list all items that may harm your operating system. Select the detected entries and click Fix Threats to get the troubleshooting completed.
Data recovery toolkit to the rescue
Some strains of ransomware are known to delete the original files after the encryption routine has been completed. As hostile as this activity appears, it can play into your hands. There are applications designed to revive the information that was obliterated because of malfunctioning hardware or due to accidental removal. The tool called Data Recovery Pro by ParetoLogic features this type of capability therefore it can be applied in ransom attack scenarios to at least get the most important files back. So download and install the program, run a scan and let it do its job.
Aesir ransomware manual removal and file recovery
Some ransomware strains terminate themselves after completing the encryption job on a computer, but some don’t. Furthermore, the Aesir virus may prevent victims from using popular antimalware tools in order to stay on board for as long as possible. Under the circumstances, it may be necessary to utilize the Safe Mode with Networking or System Restore functionality.
- Restart the machine. When the system begins loading back up, keep pressing the F8 key with short intervals. The Windows Advanced Options Menu (Advanced Boot Options) screen will appear.
- Use arrow keys to select Safe Mode with Networking and hit Enter. Log on with the user account infected by the ransomware.
- Click on the Search icon next to the Start menu button. Type msconfig in the search field and select the System Configuration option in the results. Go to the Boot tab in the upper part of the GUI.
- Under Boot options, select Safe boot and click the Apply button. A prompt will appear to reboot the computer so that the changes take effect. Select the Restart option and wait for the system to load into Safe Mode. Again, log on with the ransomware-stricken user account.
In Safe Mode, the ransom Trojan won’t keep security software from running or otherwise thwart troubleshooting. Open your preferred web browser, download and install an antimalware tool of choice and start a full system scan. Have all the detected ransomware components removed in a hassle-free way.
- Open Windows Advanced Options Menu as described in the previous section: hit F8 repeatedly when the PC is starting up. Use arrow keys to highlight the Safe Mode with Command Prompt entry. Hit Enter.
- In the Command Prompt window, type cd restore and hit Enter
- Type rstrui.exe in the new command line and press Enter
- When the System Restore screen pops up, click Next, select a restore point that predates the contamination, and use the application’s controls to roll back the system to this earlier state.
Be advised that even after the ransomware is removed, files will still be encrypted and inaccessible. The malicious code cleanup part, however, is important because it keeps a relapse of the infection from occurring further on and eliminates all opportunistic malware.
Ways of non-ransom recovery of .aesir files
Cracking the crypto used by this ransom Trojan is more of a science fiction thing rather than an attainable prospect for the masses. This is why the troubleshooting in predicaments of this sort is a matter of two approaches: one is to pay the ransom, which isn’t an option for many victims; and the other is to apply instruments that take advantage of the ransomware’s possible weaknesses. If the latter is your pick, the advice below is a must-try.
Checking one’s options regarding this workaround is doable in two ways: through the Properties menu of each file or by means of the remarkable open-source tool called Shadow Explorer. We recommend the software-based way because it’s automated, hence faster and easier. Just install the app and use its intuitive controls to get previous versions of the encrypted objects reinstated.
Alternatively, you can leverage the Previous Versions feature, which is native to Windows operating system. This method is more cumbersome that the use of ShadowExplorer, but it can help restore the most important individual files on condition that the ransomware failed to disable the Volume Snapshot Service on the computer. Right-click on a file of choice and select Properties. Then, go to the Previous Versions tab as illustrated below.
Go ahead and pick the file’s latest backup version on the list. Use the Copy or Restore buttons to reinstate this object to a new path or to its original folder, respectively.
Ransomware Prevention Tips
To avoid Aesir ransomware and other file-encrypting infections in the future, follow several simple recommendations:
- Toggle your email provider’s anti-spam settings to filter out all the potentially harmful incoming messages. Raising the bar beyond the default protection is an important countermeasure for ransom Trojans.
- Define specific file extension restrictions in your email system. Make sure that attachments with the following extensions are blacklisted: .js, .vbs, .docm, .hta, .exe, .cmd, .scr, and .bat. Also, treat ZIP archives in received messages with extreme caution.
- Rename the vssadmin.exe process so that ransomware is unable to obliterate all Shadow Volume Copies of your files in one shot.
- Keep your Firewall active at all times. It can prevent crypto ransomware from communicating with its C&C server. This way, the threat won’t be able to obtain cryptographic keys and lock your files.
- Back up your files regularly, at least the most important ones. This recommendation is self-explanatory. A ransomware attack isn’t an issue as long as you keep unaffected copies of your data in a safe place.
- Use an effective antimalware suite. There are security tools that identify ransomware-specific behavior and block the infection before it can do any harm.
These techniques are certainly not a cure-all, but they will add an extra layer of ransomware protection to your security setup.
Revise your security status
Post-factum assessment of the accuracy component in malware removal scenarios is a great habit that prevents the comeback of harmful code or replication of its unattended fractions. Make sure you are good to go by running an additional safety checkup.
- Petya ransomware removal and system recovery (upd. June 27)
- Sorebrect ransomware – fileless malware exploits PsExec utility
- Remove MOLE02 ransomware virus and decrypt .mole02 files (upd. June 15)
- Erebus ransomware infects Linux web servers in South Korea
- Decrypt .master ransomware files – BTCWare virus variant