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Callback Malware Campaign Imitates CrowdStrike and Other Big Cybersecurity Organizations

About the Attack

Earlier this month, CrowdStrike Intelligence found a callback phishing campaign copying big cybersecurity companies, including CrowdStrike. The phishing emails say that the receiver's (e-mail) company has been compromised and that the victim should contact the given phone number. The campaign incorporates similar social-engineering techniques that were used in the recent callback campaigns like WIZARD SPIDER'S 2021 Bazaar all campaign. 

The campaign is likely to include common genuine remote administration tools (RATs) for access in initial stage, off the shelf penetration testing tools for lateral movement, and execution of ransomware or extorting data. The callback campaign incorporates emails that look like it originates from big security companies, the message says that the security company found a potential issue in the receiver's network. As we have noticed in the earlier campaigns, the threat actor gives the recipient a phone number to call. 

In the past, callback campaign operators have tried to convince victims to install commercial RAT software to get an early foothold on the network. "For example, CrowdStrike Intelligence identified a similar callback campaign in March 2022 in which threat actors installed AteraRMM followed by Cobalt Strike to assist with lateral movement and deploy additional malware," says CrowdStrike. 

Current Situation 

Currently, CrowdStrike intelligence can't confirm the version in use, the callback operators will most probably use ransomware to monetize their operations. "This assessment is made with moderate confidence, as 2021 BazarCall campaigns would eventually lead to Conti ransomware — though this ransomware-as-a-service (RaaS) recently ceased operations. This is the first identified callback campaign impersonating cybersecurity entities and has higher potential success given the urgent nature of cyber breaches," says CrowdStrike.

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.

Kimsuky Hackers Employ Commodity RATs with Custom Gold Dragon Backdoor


Researchers in South Korea have discovered a fresh wave of activity from the Kimsuky hacking organization, employing commodity open-source remote access tools distributed with their own backdoor, Gold Dragon. Kimsuky, also known as TA406, is a North Korean state-sponsored hacker group that has been actively engaging in cyber-espionage efforts since 2017. The organization has shown amazing operational adaptability and threat activity diversity, participating in malware distribution, phishing, data harvesting, and even cryptocurrency theft. 

Beginning in January 2021, TA406 began delivering malware payloads through phishing emails that led to 7z archives. These archives contained an EXE file with a double extension that made it appear to be a .HTML file. If the file is opened, it will launch a scheduled activity called "Twitter Alarm," which will allow the actors to drop new payloads every 15 minutes. When run, the EXE opens a web browser to a PDF version of a valid NK News item housed on the actor's infrastructure, hoping to fool the victim into thinking they're reading a post on a news site. 

Kimsuky used xRAT in targeted assaults against South Korean entities in the most recent campaign, as discovered by experts at ASEC (AhnLab). The campaign began on January 24, 2022. xRAT is a free and open-source remote access and administration program that may be downloaded from GitHub. Keylogging, remote shell, file manager operations, reverse HTTPS proxy, AES-128 communication, and automated social engineering are among the functions provided by the malware. 

A sophisticated threat actor may choose to deploy commodity RATs for basic reconnaissance activities and do not require much configuration. This enables threat actors to concentrate their efforts on designing later-stage malware that necessitates more specialized functionality dependent on the security tools/practices available on the target. 

Kimsuky often deploys Gold Dragon as a second-stage backdoor after a fileless PowerShell-based first-stage assault that employs steganography. This malware has been recorded in a 2020 report by Cybereason and a 2021 analysis by Cisco Talos researchers, therefore it is not new. However, as ASEC describes in its study, the variation found in this latest campaign has additional functions such as the exfiltration of basic system information. 

The malware no longer leverages system processes for this operation, instead installs the xRAT tool to manually steal the required information. The RAT disguises itself as an executable called cp1093.exe, which copies a regular PowerShell process (powershell_ise.exe) to the “C:\ProgramData\” path and executes via process hollowing.

Nanocore, Netwire, and AsyncRAT Distribution Campaigns Make Use of Public Cloud Infrastructure


Threat actors are actively leveraging Amazon and Microsoft public cloud services into their malicious campaigns in order to deliver commodity remote access trojans (RATs) such as Nanocore, Netwire, and AsyncRAT to drain sensitive information from compromised systems. The spear-phishing assaults, which began in October 2021, largely targeted companies in the United States, Canada, Italy, and Singapore, according to Cisco Talos researchers. 

These Remote Administration Tools (RATs) versions are loaded with features that allow them to take control of the victim's environment, execute arbitrary instructions remotely, and steal the victim's information. 

A phishing email with a malicious ZIP attachment serves as the initial infection vector. These ZIP archive files include an ISO image that contains a malicious loader in the form of JavaScript, a Windows batch file, or a Visual Basic script. When the initial script is run on the victim's machine, it connects to a download server to obtain the next step, which can be hosted on an Azure Cloud-based Windows server or an AWS EC2 instance.

Using existing legitimate infrastructure to assist intrusions is increasingly becoming part of an attacker's playbook since it eliminates the need for the attacker to host their own servers and may also be used as a cloaking strategy to avoid detection by security solutions. 

Collaboration and communication applications such as Discord, Slack, and Telegram have found a home in many infection chains in recent months to hijack and exfiltrate data from victim machines. Cloud platform abuse is a tactical extension that attackers may utilize as the first step into a large array of networks. 

"There are several interesting aspects to this particular campaign, and it points to some of the things we commonly see used and abused by malicious actors," said Nick Biasini, head of outreach at Cisco Talos. "From the use of cloud infrastructure to host malware to the abuse of dynamic DNS for command-and-control (C2) activities. Additionally, the layers of obfuscation point to the current state of criminal cyber activities, where it takes lots of analysis to get down to the final payload and intentions of the attack."

The use of DuckDNS, a free dynamic DNS service, to generate malicious subdomains to deliver malware is also noteworthy, with some of the actor-controlled malicious subdomains resolving to the download server on Azure Cloud while other servers function as C2 for the RAT payloads.

"Malicious actors are opportunistic and will always be looking for new and inventive ways to both host malware and infect victims. The abuse of platforms such as Slack and Discord as well as the related cloud abuse are part of this pattern," Biasini concluded.

Cuba Ransomware Group Compromised the Networks of at Least 49 Organizations


The FBI has issued a new warning regarding the Cuba ransomware, stating that the gang has targeted "49 entities in five critical infrastructure sectors" and made at least $43.9 million in ransom. The FBI claimed the gang is targeting enterprises in the financial, government, healthcare, manufacturing, and information technology sectors, and is employing the Hancitor malware to gain access to Windows systems, according to an alert sent out on Friday. 

The Hancitor malware downloader is used to transmit Cuba ransomware to victims' networks, allowing the ransomware gang to have greater access to previously hacked corporate networks. Hancitor (Chancitor) is a ransomware that distributes data stealers, Remote Access Trojans (RATs), and other ransomware. It was discovered spreading the Vawtrak information-stealing trojan, according to Zscaler. Since then, it has shifted to password-stealers such as Pony and Ficker, as well as Cobalt Strike. 

Hancitor employs phishing emails and stolen passwords to get access to their victims' systems, as well as exploiting Microsoft Exchange vulnerabilities and breaking in via Remote Desktop Protocol (RDP) tools. Cuba ransomware operators would exploit legal Windows services (e.g., PowerShell, PsExec, and numerous other unspecified services) to remotely deliver their ransomware payloads and encrypt files with the ".cuba" extension once they have gained access using Hancitor.

When a victim's computer is infected, the ransomware downloads and installs a CobaltStrike beacon, as well as two executable files. Attackers can use the two files to get passwords and "write to the compromised system's temporary (TMP) file."

"Once the TMP file is uploaded, the 'krots.exe' file is deleted, and the TMP file is executed in the compromised network. The TMP file includes Application Programming Interface (API) calls related to memory injection that, once executed, deletes itself from the system. Upon deletion of the TMP file, the compromised network begins communicating with a reported malware repository located at Montenegro-based Uniform Resource Locator (URL)," the FBI explained. 

Other assault details were included by the FBI, as well as a sample ransom note and email sent by the attackers. Given their degree of activity in comparison to other more well-known ransomware gangs, experts were startled by the amount of money the group had amassed. The data, according to Emsisoft threat analyst Brett Callow, demonstrated how lucrative the ransomware market is, despite the fact that the Cuba ransomware organization is not among the top ten in terms of activity.

Nigerian Scammers Specializing in BEC Attacks Continue to Mature


Cybersecurity researchers at Palo Alto Networks Unit 42 have actively tracked the evolution of SilverTerrier Nigerian Business Email Compromise (BEC) threat actors. 

From 2014 to the present, researchers have uncovered over 170,700 samples of malware directly linked to Nigerian BEC actors. These samples have been noticed in over 2.26 million phishing attacks targeting users across all industries worldwide.

Evolution of Nigerian threat actors 

Business email compromise (BEC) attacks are one of the most financially damaging cybercrimes and have been on the rise over the past seven years. The Nigerian threat actors dubbed SilverTerrier, have contributed greatly to this growth. These threat actors are responsible for collectively producing more than 170,700 samples of malware directly linked to 2.26 million attacks, according to Palo Alto Network findings. 

SilverTerrier specializes in business email compromise attacks, the kind of email fraud in which scammers impersonate a target’s coworker or friend, then ask for wire transfers. The focus on Nigerian threat actors provides insight into one of the world’s largest subcultures given Nigeria’s historic ranking as a top-five hotspot for cybercrime. 

When first discovered in 2014, SilverTerrier included only a few individuals experimenting with commodity malware. Presently, it has 540 individual threat actors performing attacks worldwide.

Researchers at Palo Alto Networks have traced one such individual named, Onuegwu Ifeany, who studied computer science at Imo State University and launched Ifemonums-Solution LTD as a legitimate business venture in late 2014. That same year, he began his criminal activities, and from 2014 until his arrest, he registered over 150 malicious domains for personal use and to support other actors. Many of these domains also served as command-and-control infrastructure for over 2,200 samples of malware, including Pony, LokiBot, PredatorPain, ISRStealer, ISpySoftware, Remcos, and NanoCore.

Over the past seven years, researchers have also discovered over 10 different commodity information stealer families employed by SilverTerrier actors, with more effective tools being adopted over older ones. Since 2014, the threat actors have employed 13 RAT families, with LuminosityLink, NJRat, Quasar, and WarZone dropping in popularity over time, but Netwire, DarkComet, NanoCore, Remcos, ImminentMonitor, Adwind, Hworm, Revenge, and WSHRat are still actively used. 

How to protect yourself against BEC attacks? 

According to GreatHorn report, nearly 50% of all BEC attacks result from the spoofing of an individual’s identity in the display name. Among those spear phishing emails, cybercriminals are also using company names (68%), names of individual targets (66%), and the name of boss/managers (53%) to conduct their attacks. By following the steps given below you can mitigate the risks: - 

  • Avoid free web-based e-mail accounts 
  • Enable multi-factor authentication for business email accounts
  • Don’t open any email from unknown parties
  • Secure your domain 
  • Double-check the sender’s email address
  • “Forward,” don’t “reply” to business emails 
  • Know your customers and vendor’s habit 
  • Always verify before sending money or data

Nigerian BEC Fraudsters Resorting to RATs as the Tool to Amplify Attacks

The number of Business Email Compromise, also known as BEC fraud has risen up by an alarming rate; hackers have resorted to Remote Access Trojans (RAT) to amplify their attacks. 

The FBI’s Internet Crime Complaint Center, IC3 attempted to reduce the damage done by these attacks by formulating a Recovery Asset Team which took care of the consequences of  BEC scams. However, the number of scammers involved in these kinds of attacks is significantly more than ever before.

The attacks which witnessed an unprecedented upsurge are regarded as a global threat with Nigeria practicing it extensively; in the African country, money making via BEC scams have become the norm. After examining the cybercrime in Nigeria, Palo Alto Network’s Unit 42 recorded the country’s evolution into employing ransomware and malware to attain financial objectives.

In 2018, the number of groups involved in BEC scams reached up to 400 which were a hundred more than the previous year, the activities further multiplied by 54% in comparison to the year 2017.

With a monthly average of 28,227 attacks, the most affected sector was High-tech which recorded over 120,000 attacks in the previous year and the second most targeted was the wholesale industry which was subjected to around 80,000 attacks. Lastly, the third most affected sector was manufacturing, which fell prey to a total of 57,000 attacks.

Monitoring the attacks, Verizon says in a report, “Given the sheer number of incidents in this sector, you would think that the government incident responders must either be cape and tights wearing superheroes, or so stressed they’re barely hanging on by their fingernails.”

“Admittedly we do not have as much data as to what is happening beyond the deception and initial device compromise. The inclusion of keylogging malware is a good indicator that additional credential theft and reuse is a likely next step.”