Trickbot was first discovered on August 2016 as a banking Trojan which infected computers to steal email passwords and address books to spread malicious emails from compromised email accounts. It had developed new capabilities and techniques with new modules to trick users into revealing their online banking credentials. It then exfiltrate and receive the information on the attacker’s side.

Trickbot now has an additional spamming module which is known as “TrickBooster” which sends spam mails from infected computers to increase the spread of Trickbot infections. It then removes the sent messages from both outbox and sent item folders to avoid detection. It is commonly distributed in spearphishing attacks by using fake invoices and bank documents. This malware can also leverage a vulnerability in Server Message Block (SMB) to quickly propagate to other systems on the same network. Emotet, another widespread Trojan malware is also known to drop Trickbot as part of its secondary infection in Emotet-infected machines.

Behaviors

• Dropped by Emotet’s Malware-as-a-Service capability as part of secondary infection
• Remains undetected by user and gains persistence by creating a Scheduled Task
• Takes advantage of open redirections and server side injections to steal login information from user’s banking session
• Steals user data such as login state, website preferences, personalized content
• Steals remote desktop application credentials, email credentials, internet browser credentials
• Steals computer data operating system (OS) information, memory information, user accounts, installed programs, installed services, network information
• Steals information regarding Point-of-Sale (POS) systems in the network
• Disables Windows Defender and lowers down machine security

Capabilities

• Information Theft
• Exploits
• Propagation

Impact

• Financial loss – steals banking information
• Compromise system security - can disable someone’s security software
• Violation of user privacy - gathers and steals user credentials of various applications

Infection Chain

Sample: Invoice attachment spam

Additional reference

Threat Encyclopedia - TrojanSpy.Win32.TRICKBOT.TIGOCDC