Sarina

I. Targeted Entities

• Opportunistic organizations

II. Introduction

Arechclient2 is a .NET remote access trojan (RAT) that has numerous capabilities. The RAT can profile victim systems, steal information like browser and crypto-wallet data, and launch a hidden secondary desktop to control browser sessions.

III. Cyber Florida SOC Observations

Update 12/8/2022:
Cyber Florida identified additional content in analysis that was not previously reported. This information pertains to network connections. Within utilizing the InstallUtil.exe binary to execute code, the InstallUtil.exe process was observed reaching out to a pastebin[.]com page. This page contained the CnC IP address. Additionally, the victim IP address (observed in the UIP parameter) appears to be ascertained from the InstallUtil.exe process from hxxp://eth0[.]me (which appears to be a site that identifies the visiting host’s IP address). 

Original Post:
Cyber Florida has observed network payload data obfuscated via Base64 encoding and sent to what appears to be a command control server. The command and control server appears to be utilizing Google cloud services (googleusercontent.com). Within the Base64 data, exfiltrated usernames and passwords were observed. Based on observations, the exfiltrated data appears to be from cached browser credentials (Google Chrome profiles, Firefox profiles, Microsoft Edge profiles, etc.) In reviewing logs and network traffic there were parameters of interest within the data payload that would aid in identifying this activity. The following payload parameters were observed the network traffic: ConnectionType, Client, SessionID, BotName, Computer, BuildID, BotOS, URLData, UIP.

Based on observing network traffic for the command control communication, there may be similarities associated to the Redline Stealer malware. See CERT Italy article. https://cert-agid.gov.it/news/scoperto-il-malware-redline-stealer-veicolato-come-lastpass/

Screenshot samples of log and network traffic have been provided in the appendix of this report.

Some of the interesting evasion tactics Cyber Florida observed were the utilization of “sleep” functions and the usage of .NET Framework’s InstallUtil.exe binary to communicate with the command and control server. The “sleep” functionality appeared to delay the usage of InstallUtil.exe. In testing, the Installutil.exe appeared to run in perpetuity regularly communicating with the command and control server. In reviewing a few of the automated sandboxes, the Installutil.exe activity was not identified. This may be due to the “sleep” activity being utilized.

Another evasion tactic appears to be attempting to modify Windows Defender settings via the second observed PowerShell instance. The cmdlet Set-MpPreference with the options –ExclusionPath ‘C:’ was employed. This command appears to create a malware scan exclusion, which would prevent Windows Defender from scanning the entire C: volume.

The following links provide examples and context of InstallUtil.exe malware usage and abuse.

https://gbhackers.com/hiding-malware-legitimate-tool/ (not directly related to observed activity)

https://www.ired.team/offensive-security/code-execution/t1118-installutil (not directly related to observed activity)

https://attack.mitre.org/techniques/T1218/004/

During initial malicious binary execution, a persistence mechanism was observed via the common HKCUSoftwareMicrosoftWindowsCurrentVersionRun location.

IV. Additional Background Information

Blackpoint Cyber discovered an ISO file that contained a malicious Windows executable that was downloaded to a victim’s computer and was not detected by an antivirus program. A malicious executable, named Setup.exe, was observed using various defense evasion techniques including obfuscation, injection, and uncommon automation tools. These tools were used to drop a RAT named Arechclient2 (Blackpoint Cyber). The size of Setup.exe is over 300 megabytes (Blackpoint Cyber).

The initial attack vector that was used to send Setup.exe to the victim is unknown. This is the execution step. When Setup.iso is double-clicked, the ISO file can be mounted like a CD and, oftentimes, the contents of the file are automatically executed (Blackpoint Cyber). Running Setup.exe will start the extraction of three files and execute multiple child processes (Blackpoint Cyber). A new folder, IXP000.TMP, is made in the victim’s AppDataLocalTemp directory and three files are created into the newly created directory: Funding.mpeg, Mali.mpeg, and Dns.mpeg (Blackpoint Cyber).

The Dns.mpeg script is heavily obfuscated. The script searches for AvastUI.exe and AVGUI.exe running on the victim’s computer. The two executables are found in the Avast antivirus product line (Blackpoint Cyber). If those two executables are not found, Dns.mpeg sets Hole.exe.pif to the name AutoIT3.exe. In the script .au3 (or d.au3) there are over 3,000 references to a function named Xspci(). This function takes a string as its first argument and a number as its second argument. The function is responsible for decoding strings (Blackpoint Cyber).

The .au3 script accomplishes three things through injection: 1. establishing persistence using a URL file in the victim’s startup folder. 2. copying the ntdll.dll file from the C:WindowsSysWOW64 folder to avoid antivirus hooks. 3. injecting the embedded payload into jsc.exe (Blackpoint Cyber). The function that is responsible for the above tasks is KXsObHGILZNaOurxqSUainCYU() which takes a pointer to the binary to be injected, a string argument, and a string argument with the path to the binary that would be executed and injected into as arguments (Blackpoint Cyber). The script establishes persistence by adding a URL file to the victim’s startup folder that will execute a Microsoft Visual Basic Script (VBS) on every login (Blackpoint Cyber).

Arechclient2 has a decompilation phase. Test.exe, a C# binary, can be loaded into tools that statically and dynamically analyze code. One such tool is DnSpy (Blackpoint Cyber). The class names in Test.exe were minimized to single and double characters to add an additional layer of confusion for reverse engineers (Blackpoint Cyber). The actual name of Test.exe is 2qbarx12tqm.exe (Blackpoint Cyber). Arechclient2 also contains a command and control (C2) phase. When Arechclient2 is executed, it connects to https[:]//pastebin.com/raw/nJqnWX3u to collect C2 information (Blackpoint Cyber). The requested file, nJqnWX3u, contains the IP address 34[.]141[.]198[.]105 as a string. It also connects to http[:]//eth0.me to get its public IP address (Blackpoint Cyber). Arechclient2 connects to its C2 server on port 15647 to receive commands. The server responds with information to control the encryption status (“On” or “Off”) in JSON format (Blackpoint Cyber). If the communications are intercepted and the encryption is set to “Off,” further communications will be in plaintext (Blackpoint Cyber).

V. MITRE ATT&CK

• T1059.001 – Command and Scripting Interpreter: PowerShell
  Adversaries may abuse PowerShell commands and scripts for execution. PowerShell is a powerful interactive command-line interface and scripting environment included in the Windows operating system. Adversaries can use PowerShell to perform a number of actions, including discovery of information and execution of code.
• T1555.003 – Credentials From Web Browsers
  Adversaries may acquire credentials from web browsers by reading files specific to the target browser. Web browsers commonly save credentials such as website usernames and passwords so that they do not need to be entered manually in the future. Web browsers typically store the credentials in an encrypted format within a credential store; however, methods exist to extract plaintext credentials from web browsers.
• T1547.001 – Registry Run Keys / Startup Folder
  Adversaries may achieve persistence by adding a program to a startup folder or referencing it with a Registry run key. Adding an entry to the “run keys” in the Registry or startup folder will cause the program referenced to be executed when a user logs in. These programs will be executed under the context of the user and will have the account’s associated permissions level.
• T1562.001 – Impair Defenses: Disable or Modify Tools
  Adversaries may modify and/or disable security tools to avoid possible detection of their malware, tools, and activities. Adversaries may also tamper with artifacts deployed and utilized by security tools. Security tools may make dynamic changes to system components in order to maintain visibility into specific events.
• T1218.004 – System Binary Proxy Execution: InstallUtil
  Adversaries may use InstallUtil to proxy execution of code through a trusted Windows utility. InstallUtil is a command-line utility that allows for installation and uninstallation of resources by executing specific installer components specified in .NET binaries. The InstallUtil binary may also be digitally signed by Microsoft and located in the .NET directories on a Windows system: C:WindowsMicrosoft.NETFramework vInstallUtil.exe and C:WindowsMicrosoft.NETFramework64 vInstallUtil.exe.
• T1095 –Non-Application Layer Protocol
  Adversaries may use a non-application layer protocol for communication between host and C2 server or among infected hosts within a network. The list of possible protocols is extensive.
• T1132.001 –Standard Encoding
  Adversaries may encode data with a standard data encoding system to make the content of command and control traffic more difficult to detect. Command and control (C2) information can be encoded using a standard data encoding system that adheres to existing protocol specifications. Common data encoding schemes include ASCII, Unicode, hexadecimal, Base64, and MIME.

VI. Recommendations

• Phishing awareness training
  Users should be informed and educated about new kinds of phishing scams currently being used and ones that have been used in the past. Awareness training should instruct users to avoid suspicious emails, links, websites, attachments, etc. Users should also be educated about new types of attacks and schemes to mitigate risk. Recommended link: https://www.us-cert.gov/ncas/tips/ST04-014
• Set antivirus programs to conduct regular scans
  Ensure that antivirus and antimalware programs are scanning assets using up-to-date signatures
• Malware monitoring
  Continuously monitor current and new types of malware. Stay up to date on intel and advancements to prevent, defend, and mitigate these types of threats.
• Strong cyber hygiene
  Enforce a strong password policy across all networks and subsystems. Remind users to be wary of any messages asking for immediate attention, links, downloads, etc. All sources should be verified. Recommended link: https://us-cert.cisa.gov/ncas/alerts/aa21-131a
• Turn on endpoint protection
  Enable endpoint detection and response (EDR) to stop unknown malware in the product you’re using.
• Network Monitoring
  Review network logs, payload, etc. for related IP address and associated network parameters.

VII. Indicators of Compromise (IOCs)

VIII. Additional OSINT Information

• Embedded Binary
  https://www.virustotal.com/gui/file/9b2799e3fea7c214253ebba7a7cbb2b30ffe77dca6e92d8d7d25b539c4e9bd7c/details

• Main Binary
  https://www.virustotal.com/gui/file/b3eba1fcd0633a5ba27ba2715ad1e38943c2bf5e6e4182298a3bf39492f8eca4/details

• https://www.joesandbox.com/analysis/724055/0/htmL
• https://cert-agid.gov.it/news/scoperto-il-malware-redline-stealer-veicolato-come-lastpass/

IX. Appendix

This screenshot shows the payload sent to a victim, as seen by Cyber Florida. A portion of the Base64 and UIP fields have been redacted.

 The following screenshot is similar from the log above but was acquired via network packet capture. 

X. References

Blackpoint Cyber. “Ratting out arechclient2 – Blackpoint Whitepaper.” Blackpoint Cyber. Accessed November 15, 2022. https://blackpointcyber.com/lp/ratting-out-arechclient2/?utm_campaign=ratting_out_arechclient2_whitepaper&utm_source=resource_library.  

Threat Advisory created by The Cyber Florida Security Operations Center. Contributing Security Analysts: Dorian Pope, Sreten Dedic, EJ Bulut, Uday Bilakhiya. 

I. Targeted Entities

• Colorado’s official website

II. Introduction

Colorado state officials say that on Wednesday, October 5, 2022, Colorado’s website was rendered unusable as the result of an apparent cyberattack after a known Russia-based hacker group made a Telegram post saying that it would be targeting U.S. state websites. While the U.S. election system is largely disconnected from the Internet, state websites are prime targets for hackers who want to undermine confidence in elections.

III. Background Information

The cyberattack flooded the state’s website with web traffic, and is a common and simple way to disable websites. There is no indication that any of Colorado’s internal systems were accessed or that its election systems were compromised.[1] However, given how close this attack is to the U.S. midterms, experts say that the attack could give the false impression that U.S. elections are vulnerable to foreign interference.[1]

Killnet, the group responsible for the attack, is a Russian-aligned group that claims to be made up of amateur hacktivists who support Russian’s international interests. Killnet adheres to the same model that Ukraine’s IT Army (the IT Army is a Ukrainian government-affiliated movement that frequently posts a list of Russian websites on Telegram for supporters around the globe to try to overwhelm with traffic). The tactic Killnet uses to overwhelm websites with traffic is known as a distributed denial of service, or DDoS.[1] On Wednesday, KillNet posted a list of 12 target states to its Telegram channel: Alabama, Alaska, Colorado, Connecticut, Delaware, Florida, Hawaii, Idaho, Indiana, Kansas, Kentucky, and Mississippi.[1]

It is unclear if other states were affected, but federal officials have repeatedly stated that they do not expect a cyberattack to affect the midterm elections. The Cybersecurity and Infrastructure Security Agency (CISA), which oversees federal cybersecurity support for election infrastructure, released a joint announcement with the FBI saying, “any attempts by cyber actors to compromise election infrastructure are unlikely to result in large-scale disruptions or prevent voting.”[2]

Because DDoS attacks are simple to conduct and don’t inflict lasting damage or give criminals access to hidden information, cybersecurity professionals and other hackers generally regard them as unimpressive. However, Killnet has started becoming more effective at making websites unreachable, and has the potential to cause significant disruptions.[1]

IV. MITRE ATT&CK

• T1498 – Network Denial of Service
  Killnet performed a DDoS attack to degrade and block the availability of targeted websites. Network DoS can be performed by exhausting the network bandwidth services rely on.

V. Recommendations

• Set antivirus programs to conduct regular scans
  Ensure that antivirus and antimalware programs are scanning assets using up-to-date signatures
• Monitor malware
  Continuously monitor current and new types of malware. Stay up to date on intel and advancements to prevent, defend, and mitigate these types of threats.
• Turn on endpoint protection
  Enable endpoint detection and response (EDR) to stop unknown malware in the product you’re using.

VI. Indicators of Compromise (IOCs)

Because of the nature of this threat advisory, there are no IOCs. However, it is important that businesses and entities create a business continuity and disaster recovery plan in case a DDoS attack were to occur.

VII. References

(1) Collier, Kevin. “Cyberattack on Colorado State Website Follows Russian Hacktivist Threat.” NBCNews.com. NBCUniversal News Group, October 6, 2022. https://www.nbcnews.com/tech/security/colorado-state-websites-struggle-russian-hackers-vow-attack-rcna51012.

(2) “Malicious Cyber Activity Against Election Infrastructure Unlikely to Disrupt or Prevent Voting.” FBI & CISA Public Service Announcement, October 4, 2022. https://www.cisa.gov/uscert/sites/default/files/publications/PSA_cyber-activity_508.pdf.

Threat Advisory created by The Cyber Florida Security Operations Center. Contributing Security Analysts: Dorian Pope, Sreten Dedic, EJ Bulut, and Uday Bilakhiya.

I. Targeted Entities

• Edfinancial and Oklahoma Student Loan Authority loanees

II. Introduction

Oklahoma Student Loan Authority (OSLA) and EdFinancial are notifying over 2.5 million people that their personal data was leaked in a data breach that could lead to more trouble.

III. Background Information

Nelnet Servicing, a Lincoln, Nebraska-based servicing system and web portal provider for the two loan providers, was the target of the breach. Nelnet made the breach known to affected loan recipients on July 21^st via letter.[1]

By August 17^th, the investigation found that the personal user information, including the names, home addresses, email addresses, phone numbers, and social security numbers, of 2,501,324 student loan account holders had been accessed by an unauthorized party. However, the users’ financial information was not leaked.[2] In the breach disclosure filing submitted to the state of Maine by Bill Munn, Nelnet’s general counsel, the breach occurred between June 1, 2022 and July 22, 2022. But the letter sent to affected users pinpoints the breach to July 21, 2022.[3]

Although loanees’ sensitive financial data was not leaked, the personal information that was leaked “has [the] potential to be leveraged in future social engineering and phishing campaigns,” says Melissa Bischoping of Tanium. With the Biden administration’s recent announcement of a plan to cancel $10,000 of student loan debt for low- and middle-income loanees, it should be expected that this breach could be used by scammers for criminal activity. Bischoping warns that the recently leaked data can be used to impersonate affected brands in phishing campaigns that target students and recent college graduates.[4]

According to the breach disclosure, Nelnet informed Edfinancial and OSLA that Nelnet’s cybersecurity team “took immediate action to secure the information system, block the suspicious activity, fix the issue, and launched an investigation with third-party forensic experts to determine the nature and scope of the activity.” Also in the breach disclosure sent to the state of Maine is a statement that remediation will include two years of free credit monitoring, credit reports, and up to $1 million in identity theft insurance.[1]

IV. MITRE ATT&CK

• T1586 – Compromise Accounts
  Adversaries may compromise accounts with services that can be used during targeting with information gained from the data breach.

V. Recommendations

• Phishing Awareness Training
  Users should be informed and educated about new kinds of phishing scams currently being used and ones that have been used in the past. Awareness training should instruct users to avoid suspicious emails, links, websites, attachments, etc. Users should also be educated about new types of attacks and schemes to mitigate risk. Recommended link: https://www.us-cert.gov/ncas/tips/ST04-014
• Strong Cyber Hygiene
  Enforce a strong password policy across all networks and subsystems. Remind users to be wary of any messages asking for immediate attention, links, downloads, etc. All sources should be verified. Recommended link: https://us-cert.cisa.gov/ncas/alerts/aa21-131a

VI. Indicators of Compromise (IOCs)

Because of the nature of the event, this threat advisory has no indicators of compromise. However, users should continue to remain vigilant.

VII. References

(1) Nelson, Nate. “Student Loan Breach Exposes 2.5M Records.” Threatpost English Global, August 31, 2022. https://threatpost.com/student-loan-breach-exposes-2-5m-records/180492/.

Threat Advisory created by The Cyber Florida Security Operations Center. Contributing Security Analysts: Dorian Pope, Sreten Dedic, EJ Bulut.

I. Targeted Entities

• Coinbase accounts

II. Introduction

Attackers are bypassing two-factor authentication (2FA) and using other evasion tactics in a campaign that is trying to take over Coinbase accounts to defraud users of their cryptocurrency.

III. Background Information

Researchers at PIXM Software say that the threat actors are using emails that spoof Coinbase to trick users into logging into their accounts so that the attackers can gain access to the accounts and steal funds.[2] The researchers say that the cybercriminals will distribute these stolen funds through a network of “burner” accounts, in an automated way, via hundreds or thousands of transactions. The cybercriminals do this in an effort to shroud the original wallet from their destination wallet.[2]

The attackers employ a range of tactics to avoid detection. One such tactic is what researchers call “short-lived domains.” These domains are only up for extremely short periods of time (less than two hours), which is a deviation from typical phishing practices.[1] Another tactic used is context awareness. Context awareness allows cybercriminals to know either the IP, CIDR Range, or geolocation from which they anticipate their target to be connecting. The attackers can then create something similar to an Access Control List (ACL) on the phishing page to restrict connections to only be allowed from the IP, CIDR Range, or region of their intended target.[1]

The Coinbase attacks begin with criminals targeting users with a malicious email that spoofs Coinbase so that victims think that they are receiving a legitimate message. The email uses a variety of reasons to persuade the user into logging into their account. For example, the account might be locked due to suspicious activity or a transaction needs to be confirmed. Like a typical phishing campaign, if the user is persuaded to follow the link in the phony message, they are taken to a fake login page and they are prompted to enter their credentials. If the user enters their credentials, the cybercriminal receives them in real-time and uses them to log in to the legitimate Coinbase website. Because the attacker logged into the legitimate Coinbase website, the victim is sent a 2FA code from Coinbase. Thinking that they are logging into the legitimate Coinbase website, the victim enters the 2FA code they received. However, like the login credentials, the cybercriminal receives the 2FA code and gains control of the victim’s account.[1]

Once the criminal has access to the account, they divert the victim’s funds to the aforementioned network of accounts in order to evade detection or suspicion. According to researchers, the funds are often embezzled through unregulated and illegal online cryptocurrency services, like cryptocurrency casinos, betting applications, and illegal online marketplaces.[1] At this point, the victim is told that their account is locked or restricted, and is prompted to talk to customer service to rectify their problem. This prompt is the second phase of the attack, where the cybercriminal poses as a Coinbase employee trying to help the victim regain access to their account, but in reality, is stalling so that the fund transfer can be completed before the victim becomes suspicious. Once the transfer is complete, the cybercriminal will abruptly close the session and then shut down the phishing page, leaving the victim without their funds.[1]

IV. MITRE ATT&CK

• T1566 – Phishing
  The threat actors will send phishing messages to gain access to a victim’s Coinbase account.

• T1111 – Multi-Factor Authentication Interception
  The threat actors target multi-factor authentication mechanisms to gain access to credentials that are used to access Coinbase systems and services.

V. Recommendations

• Phishing Awareness Training
  Users should be informed and educated about new kinds of phishing scams currently being used and ones that have been used in the past. Awareness training should instruct users to avoid suspicious emails, links, websites, attachments, etc. Users should also be educated about new types of attacks and schemes to mitigate risk. Recommended link: https://www.us-cert.gov/ncas/tips/ST04-014
• Set Antivirus Programs to Conduct Regular Scans
  Ensure that antivirus and antimalware programs are scanning assets using up-to-date signatures.
• Strong Cyber Hygiene
  Enforce a strong password policy across all networks and subsystems. Remind users to be wary of any messages asking for immediate attention, links, downloads, etc. All sources should be verified. Recommended link: https://us-cert.cisa.gov/ncas/alerts/aa21-131a
• Turn on Endpoint Protection
  Enable endpoint detection and response (EDR) to stop unknown malware in the product you’re using.
• Malware Monitoring
  Continuously monitor current and new types of malware. Stay up to date on intel and advancements to prevent, defend, and mitigate these types of threats.

VI. Indicators of Compromise (IOCs)

This threat advisory has no indicators of compromise, but users should ensure that they are only interacting with legitimate communications from Coinbase and other services.

VII. References

(1) Montalbano, Elizabeth. “Phishers Swim Around 2FA in Coinbase Account Heists.” Threatpost English Global, August 8, 2022. https://threatpost.com/phishers-2fa-coinbase/180356/.

(2) PIXM Software, ed. “Coinbase Attacks Bypass 2FA.” Pixm Anti-Phishing, August 8, 2022. https://pixmsecurity.com/blog/phish/coinbase-attacks-bypass-2fa/.

Threat Advisory created by The Cyber Florida Security Operations Center. Contributing Security Analysts: Dorian Pope, Sreten Dedic, EJ Bulut.