Remove KOTI Ransomware (.Koti File Virus)

KOTI Ransomware makes personal files inaccessible by encrypting them

KOTI Ransomware (also known as Koti File Virus) is a malicious computer virus that encrypts personal or work files on Windows operating systems. It is the 226th extension variant of STOP/DJVU ransomware, which uses military-grade encryption method to make files inaccessible and add an extra .koti file extension after the original one. For example, a file called document.doc becomes document.doc.koti after the cyber attack. Following a successful attack, the ransomware drops ransom notes called _readme.txt in every folder that was affected by data encryption.

The ransomware uses a stealthy technique to get onto victim’s computer – it usually arrives along illegal downloads such as game or software cracks. During the data encryption procedure, the malicious ransomware showcases a fake Windows update screen to make the victim believe that there’s nothing wrong with the initial download. In addition, it disables Windows Task Manager, so that the victim could not view currently running processes and disable the virus.

In the meantime, the virus attempts to contact its Command&Control server to generate an unique encryption/decryption key and personal ID for the victim. If this connection fails, the virus uses offline key instead (same for all hosts with failed C&C connections).

Koti File Virus then begins scanning and encrypting files on all computer folders, bypassing essential OS data folders to keep the system running. It assigns additional file extension to mark affected files and creates a ransom note containing the personal ID to inform the victim about data encryption and possible recovery scenario.

It is important to note that this ransomware tends to modify Windows HOSTS file and prevent victim’s from accessing certain computer-related websites. In addition, it installs Azorult, a password-stealing malware on the system.

Ransomware aims to extort the victim

The primary aim of KOTI ransomware is to prevent the victim from accessing personal files, and force him/her to pay a specified ransom price in a certain cryptocurrency. The _readme.txt ransom note opens via default editor, Notepad, and contains a message from the cybercriminals. The crooks inform the victim that it is possible to restore encrypted files, but the victim must fulfill the attackers’ demand and pay them a ransom.

The note reads, “The only method of recovering files is to purchase .koti decrypt tool and unique key for you. This software will decrypt all your encrypted files.” The rest of the note informs that the attackers are willing to decrypt one file for free to prove that it is worth paying the ransom.

Speaking of the ransom price, Koti ransomware developers suggest 50% discount if the victim contacts them in three days (72 hours). This way, the ransom price is $490 in Bitcoin. If the victim contacts them later, the price rises to $980. Unlike similar viruses, this particular ransomware doesn’t have a payment website accessible via Tor browser. Instead, it suggests contacting the criminals via provided emails: helpmanager@mail.ch or alternative restoremanager@firemail.cc.

While we do understand that your data was important and that your primary goal now is to decrypt .koti files, we definitely do not recommend paying the ransom to cybercriminals. There are many reasons why you shouldn’t: crooks might not help you to recover the data, and by paying, you support the rising cyber crime industry. Instead of wasting your money this way, we recommend you to use it for your cyber security improvement and data backups.

You can successfully remove KOTI ransomware virus along with other malware it may have installed on your system (such as Azorult Trojan) using your anti-virus program. To repair damaged Windows system files, employ RESTORO.

Threat Summary

Name	KOTI file virus
Type	Ransomware; file-encrypting virus
Version	226th version of STOP/DJVU
Ransom note	_readme.txt
Ransom price	$490 or $980
Extension	.koti file extension
Detection names	Trojan.MalPack.GS (Malwarebytes) Win/malicious_confidence_100% (W), A Variant Of Win32/Kryptik.HCSI, Trojan-Ransom.Win32.Stop.mh and others (full list on VirusTotal)
Symptoms	Ransomware starts the attack by disabling Windows Task Manager and displaying a fake Windows update screen. It then encrypts and marks all files with .koti file extensions. Additionally, the ransomware creates and drops files named _readme.txt will in every affected folder. The note tells that there is no way to restore files except of paying a ransom.
Contact emails	helpmanager@mail.ch or restoremanager@firemail.cc
Associated processes	FF86.tmp.exe or similar; Winupdate.exe (fake Windows update prompt)
Distribution	The virus typically arrives along with software cracks, KMSPico, keygens and similar illegal downloads, typically promoted via peer-to-peer download agents
Removal	We recommend using malware-removal programs to eliminate malicious remains from your computer. To identify and repair virus damage on Windows OS files, we recommend using RESTORO.
Post-removal steps	Restore files using data backups, or, if you have been affected by the offline encryption, wait for STOP Decrypter update. Change all of your passwords due to Azorult Trojan’s activity.

Ransomware distribution explained

Ransomware-type viruses typically spread via:

• Malicious spam campaigns. Nowadays, cyber criminals can modify documents such as DOC or PDF to contain malicious macros or JavaScript to download and execute malware from external source as soon as the document is opened. Such files then are renamed into something like “invoice” or “report” and sent to work emails, urging the victim to open them as soon as possible. Such malicious campaigns often have words such as “URGENT,” “Confidential” or “IMPORTANT” in their subjects.
• Compromised websites. If hackers manage to break into a certain website and exchange downloadable files with malicious ones, they can speed up the malware distribution rapidly. Therefore, our suggestion is to have real-time protection enabled and save files to your computer instead of directly opening it. This way, you can set your antivirus to scan it first.
• Infectious downloads. Illegal downloads such as game cracks, movies and copyrighted music albums are very popular downloads, and hackers tend to pack them with malicious executables.
• Exploitable vulnerabilities in outdated software current on the target hosts. Please keep all your software, including operating system version up-to-date at all times. Software updates are issued to address not only various functionality improvements, but also security issues.

When it comes to STOP/DJVU ransomware variants such as KOTI file virus, MZLQ, SQPC, MPAL, QEWE and others, they all await victims in software cracks and similar illegal downloads. Many victims report downloading it along Adobe Photoshop Cracks, KMSpico and similar programs.

KOTI ransomware removal explained

You must remove KOTI ransomware to protect your privacy and security. To cleanse the system from the said virus and additional malware that it may have dragged into the system, we suggest using a powerful malware removal tool, such as RESTORO (includes Avira scanning engine). In addition, it can be used for fixing damaged system files, such as the affected HOSTS file.

You can find KOTI file virus removal guide down below. It was prepared by our experts and supplied with self-explanatory images to guide you through the process quickly.

PROFESSIONAL TIP. Do not forget to change your passwords after removing the malware from your system.

OUR GEEKS RECOMMEND

Our team recommends a two-step rescue plan to remove ransomware and other remaining malware from your computer, plus repair caused virus damage to the system:

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Alternative software recommendations

Malwarebytes Anti-Malware

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