TrickBot trojan which earlier wreaked havoc on Windows users by disabling Windows Defender and infecting them has now been modified to steal Windows Active Directory credentials. This new trait of the notorious trojan makes it more lethal as far as security is concerned.
Affecting Windows domain controllers, TrickBot trojan’s new module dubbed “ADll” executes a set of commands to steal Windows Active Directory information. The new module has been discovered by Sandor Nemes, a security researcher from Virus Total.
How Windows Active Directory Credentials Are Stored?
When a server acts as a domain controller, the Active Directory database is created and is saved to the default C:\Windows\NTDS folder on the domain controller.
Information including passwords, users, computers, and groups of Windows Active Directory are stored in a file called ntds.dit inside this database. Since this is highly sensitive information, Windows encrypts it using a BootKey which is stored in the System component of the Registry.Standard file operations cannot access the BootKey and a special tool called ntdsutil, used by administrators performing database maintenance is used to work with ntds.dit database.
How TrickBot Steals Active Directory Credentials?
To create a dump of Active Directory, administrators use a command named ifm (install from media). This command creates an installation media for setting up new Domain Controllers.
TrickBot trojan’s new ADll module abuses the ifm command to create a copy of the Windows Active Directory database. The entire database is dumped into the %Temp% folder. The bot then sends the collected information to the author.
The harvested data can be used to infect more computers in the network and could be used by other malware like Ryuk ransomware that is always looking for such vulnerabilities.
To learn more about how TrickBot trojan and other malware can exploit Active Directory services, you can watch this video by Vitali Kremez from SentinelLabs: