Geek's Advice

SDJM ransomware threatens to keep your files locked for good

SDJM ransomware is a malicious computer virus that is designed to encrypt all files on Windows- system. This threat is recognized as a variant of STOP/DJVU, one of the most widespread ransomware families nowadays. After breaking into the target computer, this virus locks all data and appends .sdjm extension to each file name. For example, a file originally named 1.jpg appears as 1.jpg.sdjm after being encrypted. To provide the victim with information about data recovery solution, the virus drops _readme.txt notes throughout the system. This note points out that the only way to get files back is to pay a ransom for SDJM decryption tool.

The _readme.txt note specifies that all of victim’s files, including images, videos, archives, documents and others were encrypted with strongest encryption algorithms. The note suggests that files can only be decrypted with a unique decryption key and software provided by SDJM ransomware operators. The note explains that the computer user needs to contact the attackers via provided emails – support@sysmail.ch or helprestoremanager@airmail.cc for further information.

The criminals also recommend sending one small encrypted file for test decryption to prove that they actually have the means required to decrypt files. They would reply with a decrypted file version and instructions how to make the transaction to criminals. They only accept cryptocurrency transfers since this payment method helps them to remain anonymous.

The attackers also suggest that the price of data decryption depends on how soon the user reaches out to the ransomware operators. If this is done within 72 hours/3 days, the crooks suggest a 50% discount on the decryption software price, which means that it would cost $490. If delayed any longer, the crooks would demand $980 from the victim.

If you’re considering options on what to do now, we would like to emphasize that paying the ransom is NOT RECOMMENDED by cybersecurity experts worldwide as well as FBI. Not only paying doesn’t guarantee data recovery, but it also supports cybercriminals’ operations.

Moreover, this ransomware is known to compromise computer systems with VIDAR or AZORULT Trojans, both used to steal private information such as login credentials, banking details, browsing history and cookies. Such data can be used to blackmail you endlessly.

Victims who were affected by this file-encrypting malware are advised to boot their computers in Safe Mode with Networking before attempting to remove SDJM ransomware virus. Ideally, you should use an up-to-date antivirus software for this task. If you’re interested in our recommendations, you can try INTEGO Antivirus, a robust AV with real-time protection that is simply essential security feature nowadays. In addition, you may want to download RESTORO to repair virus damage on Windows OS files.

Ransomware Summary

REMOVE MALWARE & REPAIR VIRUS DAMAGE

Avoiding ransomware infections

While there are a variety of distribution methods used for ransomware proliferation, the most common technique associated with STOP/DJVU variants such as SDJM virus relies on pirated software versions. The cybercriminals distribute fake setup files that are supposed to activate premium software licenses for free. These fake software versions can be downloaded either via rogue websites offering archived setup files secured with a password or torrents. What is even worse is that computer users with bad habits go as far as ignoring their security software alerts warning about potentially malicious download. Some of popular program names that cybercriminals are deceptively using to advertise ransomware installation files are listed below.

• Adobe Photoshop;
• KMSPico (illegal Windows activation tool);
• Tenorshare 4ukey;
• AutoCad;
• Corel Draw;
• VMware Workstation;
• Adobe Illustrator;
• League of Legends;
• Internet Download Manager;
• Various AV software.

Our team recommends you to stay away from shady websites offering paid content for free. If you’re looking for a specific software, you should visit its developer’s website or a confirmed partner’s site instead. Please, break the habit of trying to activate premium software products for free as this only exposes your computer to various security risks.

Another popular way to spread all sorts of malware including ransomware is malicious email spam. The criminals hide the payload in the email attachment that is usually named as something used in common daily communications, for instance, an invoice, waybill, order summary or similar. The malware typically comes in a form of a document such as Word, Excel or PDF file.

Do not trust suspicious emails arriving from someone that you didn’t expect to contact you. The main factor that guarantees the attackers’ success is victim’s curiosity – therefore, do not let it trick you. If you can sense that something is off with the email, never open attached files or click on inserted URLs. Moreover, if the sender’s email address looks legitimate, check if it wasn’t spoofed.

Cybercriminals can also distribute ransomware along fake software update tools. When browsing the Internet, do not rely on aggressive ads that pop up on your screen and claim that you need to update your computer programs. Legitimate software developers do not rely on such annoying marketing techniques and instead send reminders via software notifications directly. If you receive such ads frequently, you may want to check your computer for adware or at least review the websites you’re choosing for your daily browsing activities.

Final ransomware distribution method that we’d like to mention relies on fake data decryption tools. Beware of scammers who claim to have miracle solutions to data recovery. These can hide additional malware or another ransomware strain inside of them. If you’re looking for STOP/DJVU decryption and data repair solutions, remember that only Emsisoft and DiskTuna have trustworthy options for that.

More details about the ransomware

After breaking into the target system, the ransomware runs as an executable that’s typically named with 4 random chars. For instance, it may be named randomly as 1BG5.exe or 6D4N.exe. This main executable then downloads build.exe and build2.exe as well as winupdate.exe (this program displays fake Windows update screen). After gathering its core components, the ransomware begins the attack.

SDJM ransomware is designed to encrypt files in computers situated in specific countries only. It has been noticed that this threat suspends its processes if it detects that the victim’s computer is located in one of the following countries: Russia, Syria, Ukraine, Armenia, Tajikistan, Ukraine, Kazachstan, Kyrgyzstan, Belarus or Uzbekistan.

To find out victim’s location, the virus requests a response from https[:]//api.2ip.ua/geo.json domain and saves the result in geo.json file. This file contains country name, city name, IP address, zip code, longitude and latitude and more. You can see a screenshot of this file down below.

The virus then creates another file to store more details about the compromised system and names it as information.txt. This file contains details about the infected computer’s hardware specifics, active processes and installed software.

The ransomware then attempts to establish connection with its Command&Control server and request unique encryption key for the victim. If this works out, the victim’s files will be affected with so-called online encryption type which damages data without leaving chances to decrypt them for free. In case the virus fails to establish a connection with its server, it switches to another mode, widely known as offline encryption mode. For this encryption, it uses offline key which is hardcoded into the malware itself. This encryption type gives hope to decrypt files in the future, because the encryption key used is identical for all victims of offline encryption.

In other words, all those victims can recover their files using the same decryption key; therefore, if someone obtains the decryption key from the criminals and shares it with cybersecurity experts, the official decryption tool created by Emsisoft gets updated and becomes capable of restoring files encrypted by that specific virus version.

The virus creates two files to store the discussed information. The first file, located at
C:\Users\admin\AppData\Local\bowsakkdestx.txt is designed to store the encryption key and victim’s ID, while C:\SystemID\PersonalID.txt file holds the ID only. You can check whether you’re affected by offline encryption type by looking at your PersonalID.txt file – if the last two characters are t1, it means offline key was used. You can see screenshot of both files below.

The ransomware then begins encrypting all data on the computer and connected drives. The virus marks each file with additional .sdjm extension to make it clear which files were affected by the malware. The encryption type used is Salsa20 additionally secured with RSA-2048.

The malware drops a copy of the ransom note in each folder. Screenshot of the ransom-demanding message is displayed below.

After encrypting victim’s data, the virus deletes Volume Shadow Copies from the computer by running the following task in Command Prompt:

^{vssadmin.exe Delete Shadows /All /Quiet}

Finally, the ransomware edits Windows HOSTS file by adding a list of domains and mapping them to localhost IP. This creates a DNS resolution error when trying to access these specific domains on victim’s computer. As a result, the computer user cannot access a set of cybersecurity blogs publishing relevant information on ransomware incidents and recommended response. When trying to open these sites, errors like DNS_PROBE_FINISHED_NXDOMAIN might appear in web browser window.

Remove SDJM Ransomware Virus and Decrypt Your Files

Victims of this STOP/DJVU malware variant are advised to remove SDJM ransomware virus with a robust antivirus software. Before running the AV solution, we recommend booting your computer in Safe Mode with Networking as explained in the guide provided by our team below. Booting in this mode is important because it deactivates malicious processes that might attempt to block your security software.

In case you do not have antivirus yet, you may want to use INTEGO Antivirus, a trustworthy program that continuously demonstrates excellent malware detection rates. It can also protect your computer in real-time to prevent further infections as you browse the Internet. Afterward, we recommend you to download RESTORO for repairing virus-damaged Windows OS files and minimising the impact of the malware.

Our team also recommends you to:

• Inform your local police department about the ransomware attack.
• Use your backup devices to restore as many files as possible.
• Learn possible ways files affected by STOP/DJVU could be decrypted.
• Change all passwords that were used on the compromised computer.

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:

STEP 1. REMOVE AUTOMATICALLY WITH ROBUST ANTIVIRUS

REMOVE & PROTECT WITH INTEGO

Get INTEGO ANTIVIRUS for Windows to remove ransomware, Trojans, adware and other spyware and malware variants and protect your PC and network drives 24/7.. This VB100-certified security software uses state-of-art technology to provide protection against ransomware, Zero-Day attacks and advanced threats, Intego Web Shield blocks dangerous websites, phishing attacks, malicious downloads and installation of potentially unwanted programs.

Use INTEGO Antivirus to remove detected threats from your computer.

Read full review here.

STEP 2. REPAIR VIRUS DAMAGE TO YOUR COMPUTER

DOWNLOAD RESTORO

RESTORO provides a free scan that helps to identify hardware, security and stability issues and presents a comprehensive report which can help you to locate and fix detected issues manually. It is a great PC repair software to use after you remove malware with professional antivirus. The full version of software will fix detected issues and repair virus damage caused to your Windows OS files automatically.

RESTORO uses AVIRA scanning engine to detect existing spyware and malware. If any are found, the software will eliminate them.

Read full review here.

GeeksAdvice.com editors select recommended products based on their effectiveness. We may earn a commission from affiliate links, at no additional cost to you. Learn more.

Norbert Webb

Norbert Webb is the head of Geek’s Advice team. He is the chief editor of the website who controls the quality of content published. The man also loves reading cybersecurity news, testing new software and sharing his insights on them. Norbert says that following his passion for information technology was one of the best decisions he has ever made. “I don’t feel like working while I’m doing something I love.” However, the geek has other interests, such as snowboarding and traveling.