Hacker group compromises MSSQL servers to deploy FreeWorld ransomware

Poorly secured Microsoft SQL (MSSQL) servers have develop into a favourite goal for a lot of teams of attackers together with ransomware gangs. In a current assault marketing campaign dubbed DB#JAMMER hackers used brute-force assaults to compromise MSSQL servers and deploy Cobalt Strike and a variant of the Mimic ransomware known as FreeWorld.

“One of many issues that makes DB#JAMMER standout is how the attacker’s tooling infrastructure and payloads are used,” researchers from safety agency Securonix mentioned in a new report. “A few of these instruments embrace enumeration software program, RAT payloads, exploitation and credential stealing software program, and at last ransomware payloads.”

Preliminary entry to MSSQL servers and reaching persistence

The attackers use brute-force methods to guess credentials for the focused MSSQL servers, nevertheless it’s not clear if this concerned dictionary-based or password spray makes an attempt. The latter normally entails username and password combos obtained from different database leaks.

Following the preliminary entry, the attackers investigated the database by enumerating all customers with entry to it and checked if a perform known as xp_cmdshell was enabled. This Transact-SQL assertion permits database customers to execute shell instructions in Home windows and return the output as textual content. The attackers leveraged xp_cmdshell extensively, first to collect details about the system and the community surroundings by invoking Home windows instruments like wmic.exe, web.exe and ipconfig.exe, then to make modifications to Home windows accounts and the system registry.

“Three new customers had been created on the sufferer host which embrace home windows, adminv$, and mediaadmin$,” the Securonix researchers mentioned. “Every consumer was added to the ‘distant desktop customers’ and ‘directors’ [groups]. Apparently sufficient the attackers tried to execute a big one-liner, which might create the customers and modify group membership. Nonetheless, a number of variations of the command had been executed to account for teams in several languages: [English, German, Polish, Spanish, and Catalan].”

Additional modifications had been made to the brand new customers so their passwords and logged in periods would by no means expire. The modifications to the registry had been additionally intensive and included enabling the Distant Desktop Protocol (RDP) service, disabling Consumer Entry Management restrictions, and hiding distant logged in customers from the native login display screen.