Examining the Black Basta Ransomware’s Infection Routine

Ransomware

We analyze the Black Basta ransomware and examine the malicious actor’s familiar infection tactics.

By: Ieriz Nicolle Gonzalez, Ivan Nicole Chavez, Katherine Casona, Nathaniel Morales May 09, 2022 Read time: ( words)

Black Basta, a new ransomware gang, has swiftly risen to prominence in recent weeks after it caused massive breaches to organizations in a short span of time.

On April 20, 2022, a user named Black Basta posted on underground forums known as XSS.IS and EXPLOIT.IN to advertise that it intends to buy and monetize corporate network access credentials for a share of the profits. The advertisement also specified that it was looking for organizations based in the United States, Canada, United Kingdom, Australia, and New Zealand, which are all English-speaking countries. A report noted that malicious actors acquired stolen credentials from some darknet websites that peddle an enormous amount of exfiltrated data to the underground market.

On April 26, Twitter user PCrisk tweeted about the new Black Basta ransomware that appends the extension .basta and changes the desktop wallpaper.

This blog entry takes a closer look at the Black Basta ransomware and analyzes this newcomer’s familiar infection techniques.

The infection routine

Black Basta ransomware needs administrator rights to run. It otherwise displays a command prompt message as shown on Figure 1.

Figure 1. A command prompt is displayed if Black Basta ransomware is not run with administrator rights.

After running the ransomware as administrator, it removes shadow copies, disables Windows recovery and repair, and boots the PC in safe mode.

C:\Windows\SysNative\vssadmin.exe delete shadows /all /quiet
C:\Windows\SysNative\bcdedit.exe /deletevalue safeboot
C:\Windows\SysNative\bcdedit /set safeboot networkChanges

Figure 2. Commands such as "C:\Windows\SysNative\bcedit /set safeboot networkChanges" are embedded in the binary and can be viewed easily — Figure 2. Commands such as “C:\Windows\SysNative\bcedit /set safeboot networkChanges” are embedded in the binary and can be viewed easily.

It also drops the following files, which will be used later when changing the desktop wallpaper and icons for encrypted files:

%Temp%\fkdjsadasd.ico
%Temp%\dlaksjdoiwq.jpg

Before booting the infected device into safe mode, it changes the desktop wallpaper by dropping the .jpg file into the %temp% folder and creating the following registry entry:

Key: HKCU\Control Panel\Desktop; Value: Wallpaper; Data:%Temp%\dlaksjdoiwq.jpg;

Figure 3. The registry entry created after Black Basta ransomware changes the wallpaper on the infected machine

Figure 4. The desktop wallpaper created by the ransomware from the .jpg file dropped in the %temp% folder

After changing the desktop wallpaper, it then adds the following registry keys to change the icon of the encrypted files with the .basta extension:

HKLM\SOFTWARE\Classes\.basta
HKLM\SOFTWARE\Classes\.basta\DefaultIcon data: %TEMP%\fkdjsadasd.ico

Figure 5. The registry keys added by the ransomware to change the icon of the files with the .basta extension

The ransomware proceeds to encrypt files while the device is in safe mode, appending all encrypted files with the .basta extension. The ransom note is found in all the folders the ransomware has affected.

Figure 6. The infected files shown with the .basta extension

The ransom note indicates the malicious actor’s onion site and a company ID. Despite running the same ransomware (SHA256 hash: 5d2204f3a20e163120f52a2e3595db19890050b2faa96c6cba6b094b0a52b0aa) on different virtual machines, the company ID the gang provides is the same across all devices.

Figure 7. The ransom note dropped by Black Basta

Using another binary (SHA256 hash: 7883f01096db9bcf090c2317749b6873036c27ba92451b212b8645770e1f0b8a), a different company ID is shown on the ransom note. The files are likewise appended with the .basta extension.

Figure 8. A different company ID is given when another binary is used.

Analyzing the infection routine

Black Basta’s recent entry to the cybercrime world suggests that information about their operations is still limited. According to a report, the gang has neither started marketing its operations nor has it begun recruitment of affiliates in underground forums. Based on advertisements they posted before the attacks, the malicious actor likely uses stolen credentials — purchased in darknet websites or underground forums — to get into an organization’s system.

We probed further and found that the company ID written in the ransom note is hardcoded in the binary file.

Figure 9. The company ID in the ransom note is hardcoded in the binary file.

Black Basta attempts to delete shadow copies using vssadmin.exe and boots the device in safe mode using bcdexit.exe from different paths, specifically, %SysNative% and %System32%.

Black Basta’s attempts to delete shadow copies using vssadmin.exe

Figure 10. Black Basta’s attempts to delete shadow copies using vssadmin.exe

Figure 11. Black Basta boots the device in safe mode using bcdexit.exe from different paths, specifically, %SysNative% and %System32%.

At this stage, the ransomware deletes the service named Fax, and creates a new one with the same name using the malware’s path and adds it to the registry for persistence.

Figure 12. Pop-up notification when the Fax service is deleted

Figure 13. Functions used in creating a new service, also named “Fax,” that uses the file path of the malware as its binary path name

Figure 14. Functions used when creating a registry key

Figure 15. New registry key created for the new “Fax” service that replaces the deleted service

It then uses ShellExecuteA to shut down and restart the victim’s machine.

Figure 16. Function ShellExecuteA used to shut down and restart the victim’s machine

Extortion phase

For a newcomer in the field, Black Basta is quite prolific for having compromised at least a dozen organizations in just a few weeks. The group’s first known attack using the Black Basta ransomware occurred in the second week of April 2022. But an earlier sample was also spotted back in February 2022 with the ransomware name “no_name_software,” which appends the extension “encrypted” to encrypted files. According to some threat researchers, it appears that Black Basta has been in development since early February 2022.

Figure 17. Ransom note used in an earlier sample

Like other enterprise-focused ransomware operations, Black Basta employs a double extortion scheme that involves exfiltrating confidential data before encryption to threaten victims with public release of the stolen data.

The gang carries out the extortion phase of its attacks on its Tor site, Basta News, which contains a list of all the victims who have not paid the ransom.

Figure 18. Black Basta’s leak site, retrieved here — Figure 18. Black Basta’s leak site, retrieved from https://twitter.com/MarceloRivero/status/1519398885193654273

Possible relation to an APT

Security researchers exchanged speculations on Twitter that Black Basta is possibly a rebranding of the Conti ransomware operation. MalwareHunterTeam pointed out many similarities in its leak site, payment site, and negotiation style to those of Conti’s. Twitter user Arkbird echoed the same observation.Lawrence Abrams of BleepingComputer also mentioned that the malicious actors behind Black Basta seem like they are exerting a lot of effort to avoid any resemblance to their previous identity.

We have also noticed some similarities between the Black Basta and Black Matter payment sites. Like Black Matter, Black Basta implements user verification on its Tor site. However, the leak site does not implement a session key.

Figure 19. The Black Matter payment site

Insights

The malicious actors could be using a unique binary for each organization that they target. This can be seen from the ransom note that they drop, which is hardcoded in the malware itself. A ransomware typically creates a unique ID for each victim despite being infected by the same executable. Their choice of target organizations also suggests this to be the case. They buy corporate network access credentials in underground markets, which could mean that they do not distribute their malware sporadically. Instead, they use a certain kind of binary or variant for a specific organization.

Recommendations

Threat researchers suggest that the recent attacks by Black Basta can be seen as early manifestations of Conti’s rebranding efforts. True or not, organizations should keep a watchful eye against ransomware threats. An organization’s thorough assessment of its security posture and its implementation of solid cybersecurity defenses give it a better fighting chance against such threats.

To protect systems against similar attacks, organizations can establish security frameworks that allocate resources systematically for establishing a strong defense strategy against ransomware. Here are some best practices that organizations can consider:

Audit and inventory

Take an inventory of assets and data
Identify authorized and unauthorized devices and software
Audit event and incident logs

Configure and monitor

Manage hardware and software configurations
Grant admin privileges and access only when necessary to an employee’s role
Monitor network ports, protocols, and services
Activate security configurations on network infrastructure devices such as firewalls and routers
Establish a software allowlist that only executes legitimate applications

Patch and update

Conduct regular vulnerability assessments
Perform patching or virtual patching for operating systems and applications
Update software and applications to their latest versions

Protect and recover

Implement data protection, backup, and recovery measures
Enable multifactor authentication (MFA)

Secure and defend

Employ sandbox analysis to block malicious emails
Deploy the latest versions of security solutions to all layers of the system, including email, endpoint, web, and network
Detect early signs of an attack such as the presence of suspicious tools in the system
Use advanced detection technologies such as those powered by AI and machine learning

Train and test

Regularly train and assess employees in security skills
Conduct red-team exercises and penetration tests

A multilayered approach can help organizations guard possible entry points into their system (endpoint, email, web, and network). Security solutions can detect malicious components and suspicious behavior, which can help protect enterprises.

Trend Micro Vision One™ provides multilayered protection and behavior detection, which helps block questionable behavior and tools before the ransomware can do any damage.
Trend Micro Cloud One™ – Workload Security protects systems against both known and unknown threats that exploit vulnerabilities. This protection is made possible through techniques such as virtual patching and machine learning. 
Trend Micro™ Deep Discovery™ Email Inspector employs custom sandboxing and advanced analysis techniques to effectively block malicious emails, including phishing emails that can serve as entry points for ransomware.
Trend Micro Apex One™ offers next-level automated threat detection and response against advanced concerns such as fileless threats and ransomware, ensuring the protection of endpoints.

Indicators of Compromise (IOCs)

SHA256	Trend Micro Detection
5d2204f3a20e163120f52a2e3595db19890050b2faa96c6cba6b094b0a52b0aa	Ransom.Win32.BASTACRYPT.THDBGBB
7883f01096db9bcf090c2317749b6873036c27ba92451b212b8645770e1f0b8a	Ransom.Win32.BASTACRYPT.YXCD2
ae7c868713e1d02b4db60128c651eb1e3f6a33c02544cc4cb57c3aa6c6581b6e	Ransom.Win32.BASTACRYPT.THDBIBB
17205c43189c22dfcb278f5cc45c2562f622b0b6280dcd43cc1d3c274095eb90	Ransom.Win32.BASTACRYPT.YXCD2
a54fef5fe2af58f5bd75c3af44f1fba22b721f34406c5963b19c5376ab278cd1	Ransom.Win32.BASTACRYPT.THDBGBB
1d040540c3c2ed8f73e04c578e7fb96d0b47d858bbb67e9b39ec2f4674b04250	Ransom.Win32.BASTACRYPT.YXCD2
2967e1d97d32605fc5ace49a10828800fbbefcc1e010f6004a9c88ef3ecdad88	Ransom.Win32.BASTACRYPT.YXCD2.note
f088e6944b2632bb7c93fa3c7ba1707914c05c00f9491e033f78a709d65d7cff	Ransom.Win32.BASTACRYPT.YXCD2.note

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