Gac ransomware is a hazardous computer virus that is part of Dharma/CrySis malware family. Data that are affected by this virus becomes inaccessible due to the applied cipher technique in scrambling the first sets of bytes of the target file. It is really the goal of Gac ransomware to deny user’s from accessing their precious files. This way, attacker’s may have the reason to demand money from the victims as payment for the recovery software that will decrypt all the locked files.
File encryption and more
The moment that computer user runs the virus either via spam emails, cracked applications, malicious software bundles, dubious ads, or other Trojan infection, it will establish the communication to the hacker’s server. Gac ransomware accepts commands from the said server and will begin encrypting target data as soon as it gathers necessary information from the infected computer. A public key is requested to the server and Gac will use it during the file encryption process.
Similar to other variants of Dharma/Crysis as 21btc, Suka, and Yoad, Gac will encrypt the majority of files using a combination of AES-256 + RSA 1024. That only means that getting the decryption tool from someone else is impossible. Although Gac ransomware used to target as many files as it can, this virus is bypassing system files and applications. Hence, it will make sure that users may not have access to security websites by altering the Windows Hosts file. Blocking the online navigation on the infected computers makes it much difficult for victims to deal with Gac, especially now that it cannot download anti-virus tools and needed applications.
Decrypting .gac Files
Encrypted files vividly display the signs of infection by manifesting an appended extension. The virus is able to rename the data and it adds unique id, attacker’s email address, and the unique .gac file extension. In the end, the common file portrait.jpg will have a new format as portrait.jpg.id-C241D720.[email@example.com].gac.
Attackers are very detailed in explaining on their ransom note file that victims can still return the files to their original format. All they need to do is to communicate with the owners of Gac ransomware in order to purchase the decryption tool.
[expand title=”Technical Data of Gac Ransomware”]
|Threat Name||Gac Ransomware, Dharma, CrySis|
|Threat Type||Crypto-virus, File Locker, Encryption Virus|
|Encryption Method||AES-256 combined with RSA-1024 Asymmetric Encryption|
|File Extension||.id-(unique ID).[firstname.lastname@example.org].gac|
|Ransomware Note File||FILES ENCRYPTED.txt|
|Virus Alias||AhnLab-V3 : Trojan/Win32.Crysis.R213980|
ALYac : Trojan.Ransom.Crysis.E
Avast : Win32:RansomX-gen
BitDefender : Trojan.Ransom.Crysis.E
CAT-QuickHeal : Ransom.Crysis.A3
ClamAV : Win.Trojan.Dharma-6668198-0
Comodo : TrojWare.Win32.Crysis.D@6sd9xy
DrWeb : Trojan.Encoder.3953
Emsisoft : Trojan.Ransom.Crysis.E (B)
eScan : Trojan.Ransom.Crysis.E
ESET-NOD32 : A Variant Of Win32/Filecoder.Crysis.P
F-Secure : Trojan.TR/Dropper.Gen
Kaspersky : Trojan-Ransom.Win32.Crusis.to
Malwarebytes : Ransom.Crysis
McAfee : Ransom-Dharma!D4F167BF8E83
Microsoft : Ransom:Win32/Wadhrama!hoa
Rising : Ransom.Crysis!1.A6AA (CLASSIC)
Sophos : ML/PE-A + Troj/Criakl-G
SUPERAntiSpyware : Ransom.Crysis/Variant
Symantec : Ransom.Crysis
Tencent : Trojan-Ransom.Win32.Crysis.a
TrendMicro : Ransom.Win32.CRYSIS.SM
Backup your files
One important step before proceeding with the procedures below is to backup your files. Ransomware are not the same. Each has its unique sets of payloads aside from encrypting the files with complex method. Others tend to delete the infected files after certain period, while others keep them concealed on hidden places. In addition, ransomware decryption tools are not guaranteed to be perfect, there are instances that files suffer from damages during the decryption process.
So, create a backup copy of your entire Gac encrypted files right now.
Gac Ransomware Removal Guide
First thing to do is remove the Gac virus before attempting the decryption. Remember that as long as the ransomware is active, it will repeatedly encrypt the files on the compromised computer.
Infection of Gac ransom virus is dangerous to the system because it can inject files that runs each time Windows starts. To prevent the malicious files from loading, Windows operating system must run with minimal process and it can be done through SafeMode With Networking.
Quick Fix - Scan the PC with Combo Cleaner for Windows
Combo Cleaner is a trusted PC security and optimization tool equipped with powerful virus and malware detection engine. This program can get rid of ransomware like Gac through this procedure.
1. Download the application from the following page:
2. Save the file to your preferred location.
3. Double-click the downloaded file CCSetup.exe and install with the default settings.
4. At the end of the setup process, click Finish to run Combo Cleaner.
5. The tool will update the signature file, please wait for this process to complete.
6. To begin checking for threats like Gac, click on the Start Scan button. Wait for this scan to finish.
7. At the end of the scan process, click on Remove all threats to delete Gac ransomware including all malicious objects from the computer.
Free features of Combo Cleaner for Windows include Disk Cleaner, Big Files finder, Duplicate files finder, and Uninstaller. To use antivirus, privacy scanner, and to delete identified threats, users have to upgrade to a premium version.
Please continue with the succeeding removal procedures if your are comfortable to manually get rid of the threat and malicious items linked with it.
Stage 1 : Temporarily Disable System Restore on Windows OS
Because Gac and relevant virus is capable of reinstating itself by exploiting the System Restore of Windows, we suggests that you temporary disable System Restore while executing the steps. This option is also helpful to effectively run a full scan on the computer.Do not forget to enable back System Restore after completing the removal of Gac ransomware. This feature is vital in reinstating the operating system to previous normal working condition in case of problems or conflicts occurs.
Stage 2 : Start Windows in Safe Mode With Networking
Windows 10/11 Guide
1. Click on Windows logo and select Power icon when options pop-ups.
2. Select Restart from the options while pressing Shift key on the keyboard.
3. Choose an Option window will appear, select the Troubleshoot button.
4. On next window, please choose Advanced Option.
5. On Advanced Option window, click on Startup Settings and then, click Restart button to reboot the computer.
6. When Windows boot on Startup Settings, press function key F5 or number 5 on keyboard.
A simpler alternative for Windows 10 users is to scan the computer with Microsoft Defender Offline. This will run a virus scan in the recovery environment.
Windows 8 Guide
1. Click Windows Start icon at the lower left section of the screen.
2. Open Search window and type Advanced in the field. It will open General PC Settings.
3. Click on Advanced Startup and then, click on Restart Now button.
4. Once the computer starts in Advanced Startup option menu, select Troubleshoot.
5. Next, click on Advanced Options to reveal the next section.
6. Click Startup settings and then, click Restart button to boot the PC in Startup Settings.
7. Use function key F5 or number key 5 to Enable Safe Mode with Networking.
Stage 3 : Scan the Computer with Sophos Antivirus
Ransomware files are placed deeply into the system and on various locations, thus, thorough scanning is vital to totally remove Gac virus. Aside from our suggested tool, you may also run your own security program.
To remove Gac automatically, scanning the computer with this efficient anti-malware tool is suggested. This scanner does not just uncover known threats like viruses or malware, it is also effective in discovering hazardous ransomware like Gac.
1. Download Sophos Virus Removal Tool from the link below. Save the file on your computer where you can easily access it.
2. Once the download completes, browse the location of the file. Double-click to run the program and begin the install process.
3. On first windows of installation wizard, click Next to continue. Then, it will display the program’s License Agreement. You need to Accept the terms in order to proceed. If Windows prompts for User Account Control, please click Yes to proceed.
4. On succeeding windows, click Next or Continue to carry on with the installation. After completing the installation process, Launch Sophos Virus Removal Tool.
5. Internet connection is required when running this virus scanner in order to download important updates. Make sure that everything is up-to-date to effectively remove Gac ransomware and other relevant viruses.
6. Click the Start Scanning button to inspect the computer. This will check the system for presence of malicious objects, malware, and viruses. The tool reveals items that were found linked to Gac and other suspicious entities. Be sure to remove all identified threats.
The above procedures should have totally eliminated Gac ransomware. However, if you found that there are still remnants of the virus, please proceed to succeeding procedures below.
Stage 4 : Double-check with Microsoft's Malicious Software Removal Tool
1. Download the free scanner called Malicious Software Removal Tool.
2. The tool automatically checks the operating system and suggest appropriate download version. Click on Download button to begin. Save the file to a convenient location, preferably on Desktop.
3. After downloading the file, Windows will prompt that download has completed. Click Run to start scanning for Gac ransomware. Another option is to browse the location folder and double click on the file to run.
4. The tool will display Welcome screen, click Next. Please note the message "This tool is not a replacement for an antivirus product." You must understand that this program is made specifically to find and remove malware, viruses, Trojans, and other harmful elements on the computer. It was not designed to protect the computer.
5. Next, you will see Scan Type. Please choose Full Scan to ensure that all Gac ransom virus entities and other harmful files left on the computer will be found and removed. For advanced computer user, you can opt for Customized Scan, if there are other drives or folders you wanted to include in this scan.
6. Full scan may take a while, please wait for Malicious Software Removal Tool to complete the tasks. However, you may cancel the scan anytime by clicking on the Cancel button.
7. After scanning, the tool will reveal all identified threats. There may be other threats that our first scan fails to detect. Please remove/delete all detected items.
8. When removal procedure is complete, you may now close Malicious Software Removal Tool. We hope that Gac ransomware have been completely deleted from the computer. Please restart Windows to proceed with the normal operation.
Recover Files from Gac Ransomware Infection
On this section, we will provide ways to decrypt files infected with Gac ransomware. Aside from dedicated decryption software and common tools, other options for file recovery are provided. As much as we can, we will update this area whenever there is new and more suitable decryption tool was made available.
Decrypting Gac infected files with Emsisoft Tools
This service from Emsisoft is helpful in unlocking encrypted files without paying the ransom. The page provides the list of ransomware decryption tools. All you have to do is look for the specific tool and start recovering the Gac encrypted file.
Option 1: Windows Previous Version Tool
Windows Vista and Windows 7 have a feature called Previous Versions. However, this tool is only usable if restore point was made prior to ransomware infection. To use this tool as "recovery option" for files encypted by Gac virus, please follow these steps:
1. Open My Computer or Windows Explorer.
2. Right-click on the affected files or folders. From the drop-down list, please click on Restore previous versions.
3. New window will open display all backup copy of files and folders you wanted to recover. Choose the appropriate file and click on Open, Copy, or Restore. Restoring selected files overwrites the current locked files on the computer. The tool is not actually recovering files encrypted by Gac. Instead, it restores files from backup copy.
Option 2: Use ShadowExplorer to restore files encrypted by Gac Ransomware
Just like Previous Version tool, ShadowExplorer is taking advantage of shadow copy created by Windows. This tool allows you to retrieve older version of files before it was encrypted by Gac ransomware.
1. Download ShadowExplorer from the official web site.
2. Install the program with the default settings.
3. The program should run automatically after installation. If not, double-click on ShadowExplorer icon.
4. You can see the drop-down list on top of the console. Please select proper drive and the most recent point-in-time shadow copies of files you wish to restore prior to Gac ransomware infection.
5. Right-click on the Drive, Folder, or File you wish to restore and click Export...
6. Lastly, ShadowExplorer will prompt for location where you want to save the copy of recovered files.
How to protect the computer from Gac ransomware?
After the removal of the ransomware, it is important to prevent similar incident from happening again. In order to protect the computer effectively, computer user must know how Gac ransomware was able to infect the computer. To minimize the possible infection, staying away from the common sources of this virus is crucial.
How Gac ransomware can infect your computer?
The method of infecting the computers was found to be similar as other common viruses. Though, ransomware like Gac is seen to have efficient deployment via spam email messages, web injectors, malicious software installers, misleading online advertisements, and through another virus infection.
Once the virus is executed, it immediately infects the system. Then, Gac ransomware communicates to remote server so that unique key can be generated for the specific computer. After acquiring the key, it starts to decrypt target files using a complex method that is almost unbreakable. On the last stage of the attack, Gac ransomware demands for ransom money as payment for the decryption tool. To further understand the attack scheme, we have included an infographic below.
Securing the computer against ransomware attack
Do a Regular File Back-up - Always backup your data on a separate storage devices such as external hard drives, optical discs, or online backup services.
Keep Your Software Updated - Make sure that you have the latest software updates especially on the operating system. Recent updates often contain vital security patches to help protect the computer against all forms of threats.
Install a Security Program - Protect the computer with effective anti-virus application using efficient real-time scanning. Regularly run a complete scan to check the computer for presence of malware.
Protect your files with Controlled Folder Access (Windows 10)
For Windows 10 users, aside from protecting the computer using anti-virus or anti-malware programs, one way to protect against ransomware attack is by using Controlled Folder Access. This feature of Windows Defender Security Center may not prevent the Gac ransomware infection, but it can protect the folder and files in general. Follow the steps to enable Controlled Folder Access in Windows 10.
1. Go to Windows 10 Taskbar and search for Windows Defender Security Center.
2. Open Windows Defender Security Center and click on Virus & Threat Protection icon.
3. On next window, please click on Ransomware Protection.
4. Under Controlled Folder Access section, switch the slider to On. That will enable the feature and protect the folder against Gac or any type of ransomware.
5. Click on Protected Folderslink to include additional folders. Make sure that folders where important files are located should be included in the list.
Certain programs maybe blocked by Controlled Folder Access feature. To fix the issue, simply have the specific program to be white listed.
1. Under Protected Folders, click Allow an app through controlled folder access.
2. Next, click the Add an allowed app and include the target executable file.
This Controlled Folder Access feature is one way to protect files against Gac. Other important things to do in keeping files safe against ransomware is through early prevention like keeping programs updated, install an efficient security program, an do regular file backup on a separate media drive.