Authorities Seized Grandoreiro Banking Malware Infrastructure

The Grandoreiro, a criminal organization that uses banking malware to commit electronic banking fraud against Spain, Mexico, Brazil, and Argentina, has been seized by authorities. It’s been operating since 2017.

Through fraudulent actions, the criminal group is believed to have moved at least 3.6 million euros since 2019.

The Spanish financial institution Caixa Bank claims that efforts at fraud with Brazilian banking malware were detected, potentially resulting in losses of 110 million euros. 

ESET and the Brazilian Federal Police have joined forces to attempt to take down the Grandoreiro botnet.

Overview of the Grandoreiro’s Operators

The Federal Police stated that based on evidence provided by Caixa Bank, which showed that the banking malware’s operators and programmers were located in Brazil, the investigations got underway. 

According to those conducting the investigation, the infrastructure for the Grandoreiro malware operations was hosted on cloud servers.

ESET researchers mention that the operators of Grandoreiro have misused cloud service providers like AWS and Azure to host their network infrastructure.

Through the use of command and control programs, victims’ computers might be accessed remotely, providing a means of cybertheft of valuables.

Emails with malicious messages (phishing) were used to infect victims’ devices by leading them to believe that the messages were official, such as court subpoenas, overdue invoice collections, or invoices, among other things.

Hence, the malicious file was downloaded by clicking on the link or opening the attachment, leaving the victim’s computer susceptible to malicious activity.

The funds were transferred to the accounts of criminal group members who had improperly “lent” their accounts to move illegal funds.

Generally, Grandoreiro malware allows blocking the screen of the victim, logging keystrokes, simulating mouse and keyboard activity, sharing the victim’s screen, and displaying fake pop-up windows.

“The DGA is the only way Grandoreiro knows how to report to a C&C server. Besides the current date, the domain generation algorithm (DGA) accepts static configuration as well – we have observed 105 such configurations as of this writing”, ESET said.

When researchers monitor the generated domains and the IP addresses linked to them, they find many domains generated by DGAs with various configurations resolve to the same IP address.

Nearly 41% of all victims are from Brazil, with Mexico coming in second with 30% and Spain with 28%. Less than 1 percent is made up of Argentina, Portugal, and Peru. 551 victims are connected on average each day.

The Disruption Operation

In the states of São Paulo, Santa Catarina, Pará, Goiás, and Mato Grosso, federal police officers executed 13 search and seizure orders in addition to five temporary arrest warrants.

Court decisions to seize and restrict assets and valuables are also being enforced to decapitalize the criminal enterprise and to recover assets.

The Federal Police of Brazil conducted a disruption operation that targeted individuals believed to be at the top of the Grandoreiro operation structure.