This year, we have been flooded with reports of targeted ransomware attacks. Whether it’s a city, hospital, large- or medium-sized enterprise — they are all being targeted. These attacks can result in significant damage, cost, and have many different initial infection vectors. Recently, Talos Incident Response has been engaged with a couple of these attacks, which involved the use of targeted ransomware. The concept of targeted ransomware attacks is simple: Get access to a corporate network, gain access to many systems, encrypt the data on a large chunk of them, ask for a large lump sum payment to regain access to those systems, and profit.
The first widespread targeted ransomware attacks involved the SamSam ransomware, which Cisco Talos researchers first discovered in early 2016 and were incredibly profitable, despite ending in indictments from the U.S. government.
In 2019, there have been multiple players in this space, the most prolific of which has been the Ryuk campaigns that start with Emotet and Trickbot. Other targeted ransomware attacks have involved other types of ransomware and varied attack methodology. Included in this list is ransomware like LockerGoga, MegaCortex, Maze, RobbinHood, and Crysis, among others. More recently, attackers have taken the extra step of exfiltrating data and holding it hostage, which they claim they will release to the public unless payment is received, a form of doxxing.
Over the past several months, Talos Incident Response responded to several such incidents, where an adversary gained access to an environment, deployed ransomware, and exfiltrated large amounts of data, combining elements of ransomware and doxxing attacks into a single incident.
In one incident, the attacker leveraged CobaltStrike after obtaining access to the network. CobaltStrike is a widely used framework for offensive and red-teaming, which is also commonly used by adversaries to attack their targets. Once the adversary has access, they spend at least a week laterally moving around the network and gathering systems and data along the way. Combined with CobaltStrike, the actor used a technique commonly associated with APT-29, leveraging a named pipe (i.e. \\.\pipe\MSSE-<number>-server).
Once the actor gained enough access to both data and systems, the payment mechanisms began to take form. First, the actor began exfiltrating the data that they had accumulated. They achieved exfiltration by using PowerShell to connect to a remote FTP server. Below is a snippet of the code used to achieve this exfiltration via PowerShell.