Guster Ransomware

Posted: December 23, 2016

Threat Metric

The Threat Meter is a malware assessment that SpywareRemove.com's research team is able to give every identifiable malware threat. Our Threat Meter includes several criteria based off of specific malware threats to value their severity, reach and volume. The Threat Meter is able to give you a numerical breakdown of each threat's initial Threat Level, Detection Count, Volume Count, Trend Path and Percentage Impact. The overall ranking of each threat in the Threat Meter is a basic breakdown of how all threats are ranked within our own extensive malware database. The scoring for each specific malware threat can be easily compared to other emerging threats to draw a contrast in its particular severity. The Threat Meter is a useful tool in the endeavor of seeking a solution to remove a threat or pursue additional analytical research for all types of computer users.

The following fields listed on the Threat Meter containing a specific value, are explained in detail below:

Threat Level: The threat level scale goes from 1 to 10 where 10 is the highest level of severity and 1 is the lowest level of severity. Each specific level is relative to the threat's consistent assessed behaviors collected from SpyHunter's risk assessment model.

Detection Count: The collective number of confirmed and suspected cases of a particular malware threat. The detection count is calculated from infected PCs retrieved from diagnostic and scan log reports generated by SpyHunter.

Volume Count: Similar to the detection count, the Volume Count is specifically based on the number of confirmed and suspected threats infecting systems on a daily basis. High volume counts usually represent a popular threat but may or may not have infected a large number of systems. High detection count threats could lay dormant and have a low volume count. Criteria for Volume Count is relative to a daily detection count.

Trend Path: The Trend Path, utilizing an up arrow, down arrow or equal symbol, represents the level of recent movement of a particular threat. Up arrows represent an increase, down arrows represent a decline and the equal symbol represent no change to a threat's recent movement.

% Impact (Last 7 Days): This demonstrates a 7-day period change in the frequency of a malware threat infecting PCs. The percentage impact correlates directly to the current Trend Path to determine a rise or decline in the percentage.

Threat Level:	10/10
Infected PCs:	92

First Seen:	December 23, 2016
OS(es) Affected:	Windows

The Guster Ransomware is a Trojan that blocks your files and your desktop with a combination of data-encrypting and pop-up attacks. Its threat actors use these attacks for soliciting Bitcoin payments that supposedly will unlock your screen and your data. For most PC users, other recovery options are freely available, provided that you use appropriate security procedures for disabling and removing the Guster Ransomware with a dedicated anti-malware application.

Another Hidden Tear Trojan Comes out of Hiding

Social manipulation plays an important part in many threat campaigns, including the different releases of Hidden Tear-based threats malware analysts see each week. You can see many of the 'nagging' techniques con artists use in the new the Guster Ransomware campaign, which gets its ransom money from locking your files and, then, selling the unlocking service. As a far cry from its simpler, text-based brethren, this Trojan includes such elements as a timer, audio and semi-advanced graphics.

The Guster Ransomware's data-locking attacks still have a basis on the AES encryption, which enciphers your files on a format-by-format basis, rendering them unable to be read or opened. After locking the files and inserting the '.locked' extension at the end of their names, the Guster Ransomware launches a desktop-blocking window containing its ransom demands and other features.

Instead of a simple Notepad TXT file, the Guster Ransomware uses an advanced HTML Web page for delivering its extortion demands (0.4 Bitcoins, equal to 360 dollars) for restoring the encrypted content back to normal. Signature elements of the pop-up include:

The Guster Ransomware uses a default text-to-speech feature to warn you that your data is locked by a 'strong military cryptography' in a repeating audio loop.
The Trojan's pop-up also adds timing-based elements as a numeric countdown and a progress bar. It's payment instructions bolster this theme with repeated warnings that ignore the time limit that will cause the threat actor to 'blow up' your data.
It provides other formatting elements for engaging the victim visually, including a gas mask-themed background image, flashing font colors and an animated GIF. Note that the background image is one that malware analysts connect to other Trojan campaigns, although this recycled component doesn't imply any direct relationships between the Guster Ransomware and other threats necessarily.

Getting out of a Ransomware Loop

The Guster Ransomware uses multiple methods of psychological manipulation for engendering impatience and fear into its victims while it keeps them locked out of both their files and the rest of the PC's user interface. For families of file-encoding threats with free decryption help available, such as the Guster Ransomware and the rest of the Hidden Tear family, victims should attempt these solutions before considering paying any ransom money. Otherwise, backups not compromised by the Guster Ransomware may be the only guaranteed means of recovering any enciphered data.

Since the Guster Ransomware uses its ransom message to block your screen, malware analysts suggest disabling the pop-up window before disinfecting your PC. Rebooting in Safe Mode or through a peripheral device can launch your operating system without also launching this Trojan or related threats. Anti-malware utilities, while not able to decrypt any '.locked' content still may remove the Guster Ransomware so that you can implement other recovery steps.

Notably, although the Guster Ransomware's warnings are visually and audibly intimidating, the Trojan doesn't include an auto-delete function for any of the local content. The time pressure is, as always, more of another way of tricking the victims than anything else.

Technical Details

File System Modifications

Tutorials: If you wish to learn how to remove malware components manually, you can read the tutorials on how to find malware, kill unwanted processes, remove malicious DLLs and delete other harmful files. Always be sure to back up your PC before making any changes.

The following files were created in the system:

file.exe

File name: file.exe
Size: 3.06 MB (3065344 bytes)
MD5: ec2a8d8f7853397f86a4c96fdbe01b19
Detection count: 48
File type: Executable File
Mime Type: unknown/exe
Group: Malware file
Last Updated: December 23, 2016