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Chinese APT Utilizes Ransomware to Cover Cyberespionage

 

A China-based advanced persistent threat (APT) group called Bronze Starlight has been active since the start of 2021. It appears to be using double-extortion attacks and ransomware as cover for routine, state-sponsored cyberespionage and intellectual property theft. 

The distribution of post-intrusion ransomware, including LockFile, Atom Silo, Rook, Night Sky, Pandora, and LockBit 2.0, is a feature of Bronze Starlight. Microsoft also labeled it as part of the DEV-0401 emerging threat cluster, highlighting its involvement in all phases of the ransomware attack cycle, from initial access to the payload dissemination.

China's Correlation

The threat actor has always loaded Cobalt Strike Beacon and then released ransomware on compromised computers using a malware loader known as the HUI Loader, which is solely utilized by  Chinese-based organizations. This method has not been noticed by other threat actors, according to Secureworks researchers.

Researchers from Secureworks believe that Bronze Starlight is more likely motivated by cyberespionage and intellectual property (IP) theft than financial gain due to the short lifespan of each ransomware family, victimology, and access to tools used by Chinese state hacktivists (including known vulnerabilities and the HUI Loader). HUI Loader has been used to distribute malware such as Cobalt Strike, QuasarRAT, PlugX, and SodaMaster as well as remote access trojans (RATs) at least since 2015.

Attacks carried out by the actor are distinguished by the use of vulnerabilities influencing Exchange Server, Zoho ManageEngine ADSelfService Plus, Atlassian Confluence, and Apache Log4j. This contrasts with other RaaS groups that obtain access from initial access brokers (IABs) to enter a network. 

The similarity between Ransomware 

Additionally, a familiar actor is apparent from the similarities found between LockFile, Atom Silo, Rook, Night Sky, and Pandora, the latter three of which were developed from the Babuk ransomware, the source code of which was leaked in September 2021. 

The researchers write that the use of HUI Loader to load Cobalt Strike Beacon, the configuration data for Cobalt Strike Beacon, the C2 network, and the code overlap "indicate that the same threat group is linked with these 5 ransomware families."

The use of the HUI Loader to launch next-stage encrypted payloads like PlugX and Cobalt Strike Beacons, which are used to disseminate the ransomware, is another instance of detected tradecraft. However, this technique requires first getting privileged Domain Administrator credentials. 

The main victims are American and Brazilian pharmaceutical firms, a U.S. media outlet with branches in China and Hong Kong, Lithuanian and Japanese electronic component designers and manufacturers, a U.S. legal company, and the aerospace & defense unit of an Indian conglomerate. 

To achieve this, ransomware operations not only give the threat actor a way to phish data as a result of the double extortion, but they also give them a chance to erase forensic proof of its destructive actions and distract them from data theft.

Night Sky: New Ransomware Targeting Corporate Networks

 

The new year has brought with it new ransomware named 'Night Sky,' which targets corporate networks and steals data in double-extortion attacks. 

The Night Sky operation began on December 27th, according to MalwareHunterTeam, which was the first to identify the new ransomware. The ransomware has since published the data of two victims. 

One of the victims got an initial ransom demand of $800,000 in exchange for a decryptor and the promise that the stolen material would not be made public. 

How Night Sky encrypts devices

A sample of the Night Sky ransomware seen by BleepingComputer has a personalised ransom note and hardcoded login credentials to access the victim's negotiation page. 

When the ransomware is activated, it encrypts all files except those with the.dll or.exe file extensions. The ransomware will not encrypt the following files or folders: 
AppData
Boot
Windows
Windows.old
Tor Browser
Internet Explorer
Google
Opera
Opera Software
Mozilla
Mozilla Firefox
$Recycle.Bin
ProgramData
All Users
autorun.inf
boot.ini
bootfont.bin
bootsect.bak
bootmgr
bootmgr.efi
bootmgfw.efi
desktop.ini
iconcache.db
ntldr
ntuser.dat
ntuser.dat.log
ntuser.ini
thumbs.db
Program Files
Program Files (x86)
#recycle

Night Sky appends the.nightsky extension to encrypted file names while encrypting them. A ransom letter named NightSkyReadMe.hta is included in each folder, and it provides details about what was stolen, contact emails, and hardcoded passwords to the victim's negotiation page. 

Instead of communicating with victims through a Tor site, Night Sky employs email addresses and a transparent website that runs Rocket.Chat. The credentials are used to access the Rocket.Chat URL specified in the ransom note. 

Double extortion tactic: 

Before encrypting devices on the network, ransomware operations frequently grab unencrypted data from victims. Threat actors then utilize the stolen data in a "double-extortion" scheme, threatening to leak the information unless a ransom is paid. 

Night Sky built a Tor data leak site to leak the data of victims, which now contains two victims, one from Bangladesh and the other from Japan. While there hasn't been much activity with the new Night Sky ransomware operation, one should keep a watch on it as we enter the new year.