SYSDF (.SYSDF) ransomware virus – removal and decryption options
Written by Tomas Meskauskas on (updated)
What kind of malware is SYSDF?
While checking out new file submissions to the VirusTotal website, our research team found the SYSDF ransomware. This program is part of the Dharma ransomware family. SYSDF is designed to encrypt data and demand payment for its decryption.
On our testing system, this ransomware encrypted files and altered their filenames. Original names were appended with a unique ID assigned to the victim, the cyber criminals' email address, and a ".SYSDF" extension. For example, a file titled "1.jpg" appeared as "1.jpg.id-9ECFA84E.[Dec24hepl@aol.com].SYSDF".
After this process was finished, SYSDF created two ransom notes – a pop-up window and a text file named "README!.txt". The latter were dropped onto the desktop and into all encrypted directories.
Screenshot of files encrypted by SYSDF ransomware:
Ransom note overview
SYSDF ransomware's text file states that the victim's data has been encrypted and stolen; it also urges to contact the attackers. The pop-up expands more on the ransomware infection.
This message reiterates the text file's statements. It adds that unless the victim initiates communication with the cyber criminals within 24 hours – the exfiltrated data will either be leaked or sold. Only the attackers possess the decryption key – which is necessary for file recovery – and obtaining it will require paying a ransom.
Before meeting these demands, the victim can test decryption by sending the criminals a single encrypted file (except for a database or backup). The note warns against attempting manual decryption since that may lead to permanent data loss. Additionally, seeking aid from third-parties will result in an increased financial loss.
SYSDF ransomware overview
Dharma ransomware-type programs (e.g., SYSDF) leave infected systems operational by not encrypting critical system files. The malware encrypts both local and network-shared files. Additionally, processes associated with opened ("in use") files, such as database programs, text file readers, and others – are terminated, thus avoiding encryption exemptions.
Dharma programs also attempt to prevent double encryption by not locking data affected by other ransomware. This process follows a list of data-encrypting malware that is not all-encompassing. Volume Shadow Copies are deleted – thus eliminating the recovery option.
Furthermore, these programs disable the firewall. Persistence is ensured by copying the ransomware to the %LOCALAPPDATA% path and registering it with certain Run keys, as well as starting it automatically after each system reboot.
Dharma software gathers geolocation data, which may be used to determine whether to proceed with the encryption (e.g., judge the region's economic strength, base attack continuation on geopolitical reasons, etc.).
Our extensive experience researching ransomware infections allows us to conclude that decryption is rarely possible without the attackers' interference. The sole exceptions are cases involving deeply flawed ransomware-type programs.
What is more, victims commonly do not receive the promised decryption tools – despite meeting the ransom demands. Therefore, it is expressly advised against since data recovery is not guaranteed, and paying also supports this illegal activity.
While removing ransomware from the operating system prevents it from encrypting more files – the removal does not restore already compromised data. The only solution is to recover the files from a backup (if one is available).
The general advice for ensuring data safety is to keep backups in multiple separate locations, such as remote servers, unplugged storage devices, and others.
Ransomware examples
We have analyzed countless ransomware samples; Water, Lkfr, 2023lock, Lkhy, and BackMyData are just some of our newest finds. While these programs operate in a practically identical manner, they have two significant differences in between.
Ransomware can use different cryptographic algorithms (symmetric or asymmetric) to encrypt data. Ransoms can vary between three and eight digits in USD, and the disparity depends on the intended victim (i.e., home user vs. large entity).
How did ransomware infect my computer?
SYSDF is part of the Dharma ransomware family, and these programs typically infiltrate devices through vulnerable RDP (Remote Desktop Protocol) services. The infections tend to involve brute-force and dictionary attacks. However, other infiltration and distribution techniques are not unlikely.
Generally, malware (ransomware included) is spread using phishing and social engineering tactics. Malicious programs are usually disguised as or bundled with ordinary software/media files. They can be archives (RAR, ZIP, etc.), executables (.exe, .run, etc.), documents (Microsoft Office, Microsoft OneNote, PDF, etc.), JavaScript, and so forth.
Most commonly used proliferation methods include: drive-by (stealthy/deceptive) downloads, malicious attachments/links in spam (e.g., emails, PMs/DMs, social media posts, etc.), online scams, malvertising, dubious download channels (e.g., freeware and third-party websites, Peer-to-Peer sharing networks, etc.), illegal software activation tools ("cracks"), and fake updates.
Furthermore, some malicious programs can self-spread via local networks and removable storage devices (e.g., external hard drives, USB flash drives, etc.).
| Name | SYSDF virus |
| Threat Type | Ransomware, Crypto Virus, Files locker |
| Encrypted Files Extension | .SYSDF (files are also appended with a unique ID and the cyber criminals' email) |
| Ransom Demanding Message | Text presented in the pop-up window and README!.txt |
| Free Decryptor Available? | No |
| Cyber Criminal Contact | dec24hepl@aol.com, dec24hepl@cyberfear.com |
| Detection Names | Avast (Win32:RansomX-gen [Ransom]), Combo Cleaner (Trojan.Ransom.Crysis.E), ESET-NOD32 (A Variant Of Win32/Filecoder.Crysis.P), Kaspersky (Trojan-Ransom.Win32.Crusis.to), Microsoft (Ransom:Win32/Wadhrama!pz), Full List Of Detections (VirusTotal) |
| Symptoms | Cannot open files stored on your computer, previously functional files now have a different extension (for example, my.docx.locked). A ransom demand message is displayed on your desktop. Cyber criminals demand payment of a ransom (usually in bitcoins) to unlock your files. |
| Distribution methods | Infected email attachments (macros), torrent websites, malicious ads. |
| Damage | All files are encrypted and cannot be opened without paying a ransom. Additional password-stealing trojans and malware infections can be installed together with a ransomware infection. |
| Malware Removal (Windows) | To eliminate possible malware infections, scan your computer with legitimate antivirus software. Our security researchers recommend using Combo Cleaner. |
How to protect yourself from ransomware infections?
Caution is essential to computer safety, including strong credential management practices. We recommend being vigilant when browsing since fraudulent and malicious online content typically appears legitimate and harmless.
Additionally, incoming emails and other messages must be treated with care. Attachments or links present in suspect/irrelevant mail must not be opened, as they can be virulent.
All downloads must be performed from official and verified sources. Another recommendation is to activate and update software by using legitimate functions/tools, as those obtained from third-parties can contain malware.
We must emphasize the importance of having a reputable anti-virus installed and kept up-to-date. Security programs must be used to run regular system scans and to remove detected threats and issues. If your computer is already infected with SYSDF, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate this ransomware.
Screenshot of SYSDF ransomware's pop-up window:
Text presented in this message:
We downloaded to our servers and encrypted all your databases and personal information!
If you do not write to us within 24 hours, we will start publishing and selling your data on the darknet on hacker sites and offer the information to your competitors
email us: Dec24hepl@aol.com YOUR ID -
If you haven't heard back within 24 hours, write to this email:Dec24hepl@cyberfear.com
IMPORTANT INFORMATION!
Keep in mind that once your data appears on our leak site,it could be bought by your competitors at any second, so don't hesitate for a long time.The sooner you pay the ransom, the sooner your company will be safe..
Guarantee:If we don't provide you with a decryptor or delete your data after you pay,no one will pay us in the future. We value our reputation.
Guarantee key:To prove that the decryption key exists, we can test the file (not the database and backup) for free.
Do not try to decrypt your data using third party software, it may cause permanent data loss.
Don't go to recovery companies - they are essentially just middlemen.Decryption of your files with the help of third parties may cause increased price (they add their fee to our) we're the only ones who have the decryption keys.
Screenshot of SYSDF's text file ("README!.txt"):
Text presented in this file:
Your data has been stolen and encrypted!
email us
Video showing how to remove SYSDF ransomware using Combo Cleaner:
SYSDF ransomware removal:
Instant automatic malware removal:
Manual threat removal might be a lengthy and complicated process that requires advanced IT skills. Combo Cleaner is a professional automatic malware removal tool that is recommended to get rid of malware. Download it by clicking the button below:
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Video suggesting what steps should be taken in case of a ransomware infection:
Quick menu:
- What is SYSDF virus?
- STEP 1. Reporting ransomware to authorities.
- STEP 2. Isolating the infected device.
- STEP 3. Identifying the ransomware infection.
- STEP 4. Searching for ransomware decryption tools.
- STEP 5. Restoring files with data recovery tools.
- STEP 6. Creating data backups.
If you are a victim of a ransomware attack we recommend reporting this incident to authorities. By providing information to law enforcement agencies you will help track cybercrime and potentially assist in the prosecution of the attackers. Here's a list of authorities where you should report a ransomware attack. For the complete list of local cybersecurity centers and information on why you should report ransomware attacks, read this article.
List of local authorities where ransomware attacks should be reported (choose one depending on your residence address):
USA - Internet Crime Complaint Centre IC3
United Kingdom - Action Fraud
Spain - Policía Nacional
France - Ministère de l'Intérieur
Germany - Polizei
Italy - Polizia di Stato
The Netherlands - Politie
Poland - Policja
Portugal - Polícia Judiciária
Isolating the infected device:
Some ransomware-type infections are designed to encrypt files within external storage devices, infect them, and even spread throughout the entire local network. For this reason, it is very important to isolate the infected device (computer) as soon as possible.
Step 1: Disconnect from the internet.
The easiest way to disconnect a computer from the internet is to unplug the Ethernet cable from the motherboard, however, some devices are connected via a wireless network and for some users (especially those who are not particularly tech-savvy), disconnecting cables may seem troublesome. Therefore, you can also disconnect the system manually via Control Panel:
Navigate to the "Control Panel", click the search bar in the upper-right corner of the screen, enter "Network and Sharing Center" and select search result: 
Click the "Change adapter settings" option in the upper-left corner of the window: 
Right-click on each connection point and select "Disable". Once disabled, the system will no longer be connected to the internet. To re-enable the connection points, simply right-click again and select "Enable". 
Step 2: Unplug all storage devices.
As mentioned above, ransomware might encrypt data and infiltrate all storage devices that are connected to the computer. For this reason, all external storage devices (flash drives, portable hard drives, etc.) should be disconnected immediately, however, we strongly advise you to eject each device before disconnecting to prevent data corruption:
Navigate to "My Computer", right-click on each connected device, and select "Eject": 
Step 3: Log-out of cloud storage accounts.
Some ransomware-type might be able to hijack software that handles data stored within "the Cloud". Therefore, the data could be corrupted/encrypted. For this reason, you should log-out of all cloud storage accounts within browsers and other related software. You should also consider temporarily uninstalling the cloud-management software until the infection is completely removed.
Identify the ransomware infection:
To properly handle an infection, one must first identify it. Some ransomware infections use ransom-demand messages as an introduction (see the WALDO ransomware text file below).
This, however, is rare. In most cases, ransomware infections deliver more direct messages simply stating that data is encrypted and that victims must pay some sort of ransom. Note that ransomware-type infections typically generate messages with different file names (for example, "_readme.txt", "READ-ME.txt", "DECRYPTION_INSTRUCTIONS.txt", "DECRYPT_FILES.html", etc.). Therefore, using the name of a ransom message may seem like a good way to identify the infection. The problem is that most of these names are generic and some infections use the same names, even though the delivered messages are different and the infections themselves are unrelated. Therefore, using the message filename alone can be ineffective and even lead to permanent data loss (for example, by attempting to decrypt data using tools designed for different ransomware infections, users are likely to end up permanently damaging files and decryption will no longer be possible even with the correct tool).
Another way to identify a ransomware infection is to check the file extension, which is appended to each encrypted file. Ransomware infections are often named by the extensions they append (see files encrypted by Qewe ransomware below).
This method is only effective, however, when the appended extension is unique - many ransomware infections append a generic extension (for example, ".encrypted", ".enc", ".crypted", ".locked", etc.). In these cases, identifying ransomware by its appended extension becomes impossible.
One of the easiest and quickest ways to identify a ransomware infection is to use the ID Ransomware website. This service supports most existing ransomware infections. Victims simply upload a ransom message and/or one encrypted file (we advise you to upload both if possible).
The ransomware will be identified within seconds and you will be provided with various details, such as the name of the malware family to which the infection belongs, whether it is decryptable, and so on.
Example 1 (Qewe [Stop/Djvu] ransomware):
Example 2 (.iso [Phobos] ransomware):
If your data happens to be encrypted by ransomware that is not supported by ID Ransomware, you can always try searching the internet by using certain keywords (for example, a ransom message title, file extension, provided contact emails, crypto wallet addresses, etc.).
Search for ransomware decryption tools:
Encryption algorithms used by most ransomware-type infections are extremely sophisticated and, if the encryption is performed properly, only the developer is capable of restoring data. This is because decryption requires a specific key, which is generated during the encryption. Restoring data without the key is impossible. In most cases, cybercriminals store keys on a remote server, rather than using the infected machine as a host. Dharma (CrySis), Phobos, and other families of high-end ransomware infections are virtually flawless, and thus restoring data encrypted without the developers' involvement is simply impossible. Despite this, there are dozens of ransomware-type infections that are poorly developed and contain a number of flaws (for example, the use of identical encryption/decryption keys for each victim, keys stored locally, etc.). Therefore, always check for available decryption tools for any ransomware that infiltrates your computer.
Finding the correct decryption tool on the internet can be very frustrating. For this reason, we recommend that you use the No More Ransom Project and this is where identifying the ransomware infection is useful. The No More Ransom Project website contains a "Decryption Tools" section with a search bar. Enter the name of the identified ransomware, and all available decryptors (if there are any) will be listed.
Restore files with data recovery tools:
Depending on the situation (quality of ransomware infection, type of encryption algorithm used, etc.), restoring data with certain third-party tools might be possible. Therefore, we advise you to use the Recuva tool developed by CCleaner. This tool supports over a thousand data types (graphics, video, audio, documents, etc.) and it is very intuitive (little knowledge is necessary to recover data). In addition, the recovery feature is completely free.
Step 1: Perform a scan.
Run the Recuva application and follow the wizard. You will be prompted with several windows allowing you to choose what file types to look for, which locations should be scanned, etc. All you need to do is select the options you're looking for and start the scan. We advise you to enable the "Deep Scan" before starting, otherwise, the application's scanning capabilities will be restricted.
Wait for Recuva to complete the scan. The scanning duration depends on the volume of files (both in quantity and size) that you are scanning (for example, several hundred gigabytes could take over an hour to scan). Therefore, be patient during the scanning process. We also advise against modifying or deleting existing files, since this might interfere with the scan. If you add additional data (for example, downloading files/content) while scanning, this will prolong the process:
Step 2: Recover data.
Once the process is complete, select the folders/files you wish to restore and simply click "Recover". Note that some free space on your storage drive is necessary to restore data:
Create data backups:
Proper file management and creating backups is essential for data security. Therefore, always be very careful and think ahead.
Partition management: We recommend that you store your data in multiple partitions and avoid storing important files within the partition that contains the entire operating system. If you fall into a situation whereby you cannot boot the system and are forced to format the disk on which the operating system is installed (in most cases, this is where malware infections hide), you will lose all data stored within that drive. This is the advantage of having multiple partitions: if you have the entire storage device assigned to a single partition, you will be forced to delete everything, however, creating multiple partitions and allocating the data properly allows you to prevent such problems. You can easily format a single partition without affecting the others - therefore, one will be cleaned and the others will remain untouched, and your data will be saved. Managing partitions is quite simple and you can find all the necessary information on Microsoft's documentation web page.
Data backups: One of the most reliable backup methods is to use an external storage device and keep it unplugged. Copy your data to an external hard drive, flash (thumb) drive, SSD, HDD, or any other storage device, unplug it and store it in a dry place away from the sun and extreme temperatures. This method is, however, quite inefficient, since data backups and updates need to be made regularly. You can also use a cloud service or remote server. Here, an internet connection is required and there is always the chance of a security breach, although it's a really rare occasion.
We recommend using Microsoft OneDrive for backing up your files. OneDrive lets you store your personal files and data in the cloud, sync files across computers and mobile devices, allowing you to access and edit your files from all of your Windows devices. OneDrive lets you save, share and preview files, access download history, move, delete, and rename files, as well as create new folders, and much more.
You can back up your most important folders and files on your PC (your Desktop, Documents, and Pictures folders). Some of OneDrive’s more notable features include file versioning, which keeps older versions of files for up to 30 days. OneDrive features a recycling bin in which all of your deleted files are stored for a limited time. Deleted files are not counted as part of the user’s allocation.
The service is built using HTML5 technologies and allows you to upload files up to 300 MB via drag and drop into the web browser or up to 10 GB via the OneDrive desktop application. With OneDrive, you can download entire folders as a single ZIP file with up to 10,000 files, although it can’t exceed 15 GB per single download.
OneDrive comes with 5 GB of free storage out of the box, with an additional 100 GB, 1 TB, and 6 TB storage options available for a subscription-based fee. You can get one of these storage plans by either purchasing additional storage separately or with Office 365 subscription.
Creating a data backup:
The backup process is the same for all file types and folders. Here’s how you can back up your files using Microsoft OneDrive
Step 1: Choose the files/folders you want to backup.
Click the OneDrive cloud icon to open the OneDrive menu. While in this menu, you can customize your file backup settings.
Click Help & Settings and then select Settings from the drop-down menu.
Go to the Backup tab and click Manage backup.
In this menu, you can choose to backup the Desktop and all of the files on it, and Documents and Pictures folders, again, with all of the files in them. Click Start backup.
Now, when you add a file or folder in the Desktop and Documents and Pictures folders, they will be automatically backed up on OneDrive.
To add folders and files, not in the locations shown above, you have to add them manually.
Open File Explorer and navigate to the location of the folder/file you want to backup. Select the item, right-click it, and click Copy.
Then, navigate to OneDrive, right-click anywhere in the window and click Paste. Alternatively, you can just drag and drop a file into OneDrive. OneDrive will automatically create a backup of the folder/file.
All of the files added to the OneDrive folder are backed up in the cloud automatically. The green circle with the checkmark in it indicates that the file is available both locally and on OneDrive and that the file version is the same on both. The blue cloud icon indicates that the file has not been synced and is available only on OneDrive. The sync icon indicates that the file is currently syncing.
To access files only located on OneDrive online, go to the Help & Settings drop-down menu and select View online.
Step 2: Restore corrupted files.
OneDrive makes sure that the files stay in sync, so the version of the file on the computer is the same version on the cloud. However, if ransomware has encrypted your files, you can take advantage of OneDrive’s Version history feature that will allow you to restore the file versions prior to encryption.
Microsoft 365 has a ransomware detection feature that notifies you when your OneDrive files have been attacked and guide you through the process of restoring your files. It must be noted, however, that if you don’t have a paid Microsoft 365 subscription, you only get one detection and file recovery for free.
If your OneDrive files get deleted, corrupted, or infected by malware, you can restore your entire OneDrive to a previous state. Here’s how you can restore your entire OneDrive:
1. If you're signed in with a personal account, click the Settings cog at the top of the page. Then, click Options and select Restore your OneDrive.
If you're signed in with a work or school account, click the Settings cog at the top of the page. Then, click Restore your OneDrive.
2. On the Restore your OneDrive page, select a date from the drop-down list. Note that if you're restoring your files after automatic ransomware detection, a restore date will be selected for you.
3. After configuring all of the file restoration options, click Restore to undo all the activities you selected.
The best way to avoid damage from ransomware infections is to maintain regular up-to-date backups.
Frequently Asked Questions (FAQ)
How was my computer hacked and how did hackers encrypt my files?
SYSDF belongs to the Dharma ransomware family, which usually infiltrates machines via vulnerable RDP services, with the infections relying on brute-force and dictionary attacks. Other distribution methods are possible.
Generally, victims themselves often open ransomware executables because these files are usually disguised as or bundled with ordinary software/media. This malware is mainly distributed via drive-by downloads, spam emails/messages, online scams, dubious download channels (e.g., freeware and free file-hosting sites, P2P sharing networks, etc.), illegal program activation ("cracking") tools, and fake updates.
How to open ".SYSDF" files?
Ransomware-encrypted files can neither be opened nor otherwise used – unless they are decrypted.
Where should I look for free decryption tools for SYSDF ransomware?
If you have experienced a ransomware attack, we recommend checking out the No More Ransom project website (more information above).
I can pay you a lot of money, can you decrypt files for me?
We do not offer decryption services. Aside from cases involving severely flawed ransomware, recovering encrypted files is usually impossible without the cyber criminals' interference. Therefore, third-parties offering paid decryption services are often scams or aim to act as middlemen between victims and criminals.
Will Combo Cleaner help me remove SYSDF ransomware?
Yes, Combo Cleaner will scan your device and eliminate detected ransomware infections. Note that while using an anti-virus is the first step in ransomware recovery – security programs cannot decrypt data.
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