FireEye has written a blog about what they observed financially motivated threat actors were doing that focused on disrupting business processes by the mass deployment of ransomware throughout a victim's environment. FireEye researchers James Wyke and Jeremy Kennelly say these ransomware campaigns have been accompanied with multi-million-dollar ransom amounts.
The techniques used were first reported by FireEye in April 2018.
Between May and September 2019, FireEye says that they responded to multiple incidents involving a financially motivated threat actor who was leveraging compromised web infrastructure in order to establish an initial foothold in victim environments.
Techniques used were similar to those seen earlier, but this time FireEye found the threat actors were leveraging victim systems so that they could deploy malware such as Dridex or NetSupport, and multiple post-exploitation frameworks. The threat actors' ultimate goal in some of these episodes was to ransom systems in mass with BitPaymer or DoppelPaymer ransomware.
A FakeUpdates campaign begins with a sequence of browser validation, performed before the final payload is downloaded. Injected code on the initial compromised page will make the user's browser transparently navigate to a malicious website using hard-coded parameters. After victim browser information is gleaned, additional redirects are performed and the user is prompted to download a fake browser update.
The current campaign included activities like internal reconnaissance, credential harvesting, privilege escalation, lateral movement and ransomware deployment in enterprise networks. FireEye has identified that a large number of the compromised sites serving up the first stage of FakeUpdates have been older, vulnerable Content Management System (CMS) applications.
After receiving the system information that the malware sends to the command-and-control (c2) server, the server responds with an encoded payload delivered via chunked transfer-encoding to the infected system. This technique is used because it evades conventional IDS/IPS appliances, letting the second-stage payload in.
FireEye found encoded payloads that delivered Dridex or NetSupport Manage Remote Access Tools (RATs), along with Chthonic or AZORult.
FireEye saw that the threat actors leveraged their Dridex backdoor(s) to execute the publicly available PowerShell Empire and/or Koadic post-exploitation frameworks.
Currently, the ransomware and additional reconnaissance tools are downloaded through public sharing website repositories such as DropMeFiles and SendSpace. Irrespective of the ransomware deployed (BitPaymer or DoppelPaymer), the attacker used the SysInternals utlity PSEXEC to distribute and execute the ransomware.
The DoppelPaymer ransomware was found by FireEye in an Alternate Data Stream (ADS) in randomly named files on disk. ADSs are attributes within NTFS that allow for a file to have multiple data streams, with only the primary being visible in tools such as Windows Explorer.
Threat actors are now coupling ransomware with multiple toolkits or other malware families to gain a stronger foothold into an environment. But they still have the ultimate goal of holding the victim organization hostage.
— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.