Examining the Black Basta Ransomware’s Infection Routine

Black Basta, a new ransomware gang, has swiftly risen to prominence in recent weeks after it caused massive breaches to organisations 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 monetise corporate network access credentials for a share of the profits. The advertisement also specified that it was looking for organisations 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 analyses 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.

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 organisation’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 organisations 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

New findings: QAKBOT possibly related to Black Basta

Based on our analysis of another set of samples monitored within a 72-hour timeframe, we discovered a possible correlation between QAKBOT and Black Basta ransomware. We observed the following:

As with QAKBOT, the malware is downloaded and executed from a malicious Excel file. Similar to the typical routine of the QAKBOT binary, it then executes certain PowerShell commands as part of its staging phase.
From information gathered in our telemetry, we found the presence of the Black Basta ransomware within the 72-hour period in which it encrypted files on victims’ machine. Trend Micro detects this as Ransom.Win32.BASTACRYPT.YACEDT.
Other researchers pointed out that QAKBOT deploys its version of the exploit PRINTNIGHTMARE (aka QUAKNIGHTMARE) during the same timeframe. We also observed the presence of the weaponized exploit. This, in turn, executes another binary with escalated privilege. Unfortunately, we were unable to find the presence of the file pointed by the hardcoded path. string to complete the attack chain. Trend Micro detects this as Trojan.Win64.QUAKNIGHTMARE.YACEJT.

Malicious actors also use certain tools as seen through our sensors, but we were unable to obtain the complete kit. We have so far gathered paths related to the tools themselves that include the following:

AdwareCleaner (C:\AdwCleaner\*)
Either PC-Cleaner or Pervasive PSQL/SQL (C:\pvsw\*)

The structure of the ransomware loader is also different from the external article. In this case, instead of dropping and executing the ransomware itself, the loader downloads to the device’s memory then uses reflective loading to launch the ransomware.

The information we have collected so far indicates that the malicious actor behind Black Basta possibly used QAKBOT as a new means to deliver the ransomware.

Insights

The malicious actors could be using a unique binary for each organisation 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 organisations 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 organisation.

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, organisations should keep a watchful eye against ransomware threats. An organisation’s thorough assessment of its security posture and its implementation of solid cybersecurity defences give it a better fighting chance against such threats.

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

Audit and inventory

Take an inventory of assets and data
Identify authorised and unauthorised 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 organisations guard possible entry points into their system (endpoint, email, web, and network). Security solutions can detect malicious components and suspicious behaviour, which can help protect enterprises.

Trend Micro Vision One™provides multilayered protection and behaviour detection, which helps block questionable behaviour and tools before the ransomware can do any damage.
Trend Micro Cloud One™ – Workload Securityprotects 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 Inspectoremploys 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
a54fef5fae2af58f5bd75c3af44f1fba22b721f34406c5963b19c5376ab278cd1	Ransom.Win32.BASTACRYPT.THDBGBB
1d040540c3c2ed8f73e04c578e7fb96d0b47d858bbb67e9b39aec2f4674b04250	Ransom.Win32.BASTACRYPT.YXCD2
2967e1d97d32605fc5ace49a10828800fbbefcc1e010f6004a9c88ef3ecdad88	Ransom.Win32.BASTACRYPT.YXCD2.note
f088e6944b2632bb7c93fa3c7ba1707914c05c00f9491e033f78a709d65d7cff	Ransom.Win32.BASTACRYPT.YXCD2.note

For QAKBOT-related samples:

SHA256	Trend Micro Detections
a48ac26aa9cdd3bc7f219a84f49201a58d545fcebf0646ae1d676c7e43c6ac3e	TrojanSpy.Win32.QAKBOT.YACEDT
82c73538322c8b90c25a99a7afc2fafcd7e7e03fae920a3331ef0003300ac10b8	TrojanSpy.Win32.QAKBOT.YACEDT
82c73538322c8b90c25a99a7afc2fafcd7e7e03fae920a3331ef0003300ac10b8	TrojanSpy.Win32.QAKBOT.YACEDT
2083e4c80ade0ac39365365d55b243dbac2a1b5c3a700aad383c110db073f2d9	TrojanSpy.Win32.QAKBOT.YACEDT
2e890fd02c3e0d85d69c698853494c1bab381c38d5272baa2a3c2bc0387684c1	TrojanSpy.Win32.QAKBOT.YACEDT
2d906ed670b24ebc3f6c54e7be5a32096058388886737b1541d793ff5d134ccb	TrojanSpy.Win32.QAKBOT.YACEDT
72fde47d3895b134784b19d664897b36ea6b9b8e19a602a0aaff5183c4aec7d24	TrojanSpy.Win32.QAKBOT.YACEDT
ffa7f0e7a2bb0edf4b7785b99aa39c96d1fae891eb6f89a65d76a57ff04ef17ab	TrojanSpy.Win32.QAKBOT.YACEDT
1e7174f3d815c12562c5c1978af6abbf2d81df16a8724d2a1cf596065f3f15a2	TrojanSpy.Win32.QAKBOT.YACEDT
130af6a91aa9ecbf70456a0bee87f947bf4ddc2d2775459e3feac563007e1aed	Trojan.Win64.QUAKNIGHTMARE.YACEJT
81a6c44682b981172cd85ee4a150ac49f838a65c3a0ed822cb07a1c19dab4af5	Ransom.Win32.BASTACRYPT.YACEDT
94428d7620fff816cb3f65595978c6abb812589861c38052d30fa3c566e32256	Ransom.Win32.BASTACRYPT.YACEDT
c9df12fbfcae3ac0894c1234e376945bc8268acdc20de72c8dd16bf1fab6bb70	Ransom.Win32.BASTACRYPT.YACEJT
0d3af630c03350935a902d0cce4dc64c5cfff8012b2ffc2f4coe5040fdec524ed	Trojan.Win32.BLACKBASTA.YXCEJ
3fae73707c2042fefe56d0f277a3c91b5c943393cf42c2a4c683867d6866116fc	Trojan.Win32.BLACKBASTA.YXCEJ
3fae73707c2042fefe56d0f277a3c91b5c943393cf42c2a4c683867d6866116fc	Trojan.Win32.BLACKBASTA.YXCEJ
0e2b951ae07183c44416ff6fa8d7b8924348701efa75dd3cb14c708537471d27	Trojan.Win32.BLACKBASTA.YXCEJ
8882186bace198be59147bcabae6643d2a7a490ad08298a4428a8e64e24907ad	Trojan.Win32.BLACKBASTA.YXCEJ
df35b45ed34eaca32cda6089acbfe638d2d1a3593d74019b6717afed90dbd5f8	Trojan.Win32.BLACKBASTA.YXCEJ
b8aa8abac2933471e4e6d91cb23e4b2b5a577a3bb9e7b88f95a4ddc91e22b2cb	TrojanSpy.VBS.KEYLOAD.A
fb3340d734c50coe77a9f463121cd3b7f70203493aa9aff304a19a8de83a2d3c9	TrojanSpy.VBS.KEYLOAD.A
5ab605b1047e098638d36a5976b00379353d84bd7e330f5778ebb71719c36878	TrojanSpy.VBS.KEYLOAD.A
9707067b4f53caf43df5759fae40e9121f832e24da5fae5236256ad0e258277d88	TrojanSpy.VBS.KEYLOAD.A
9707067b4f53caf43df5759fae40e9121f832e24da5fae5236256ad0e258277d88	TrojanSpy.VBS.KEYLOAD.A
d7580fd8cc7243b7e16fd97b7c5dea2d54bcba08c298dc2d82613bdc2bd0b4bf	TrojanSpy.VBS.KEYLOAD.A
919d1e712f4b343856cb920e4d6f5d20a7ac18d7386673ded6968c945017f5fd	TrojanSpy.VBS.KEYLOAD.A
012826db8d41ff4d28e3f312c1e6256f0647bf34249a5a6de7ecac452d32d917	TrojanSpy.VBS.KEYLOAD.A
d36a9f3005c5c24649f80722e43535e57fd96729e827cdd2c080d17c6a53a893	TrojanSpy.VBS.KEYLOAD.A
580coe8b7f5a373d5d7fbfbfef5204d18b8f9407b0c2cbf3bcae808f4d642076a	Backdoor.Win32.COROXY.YACEKT

Examining the Black Basta Ransomware’s Infection Routine

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