Financially Motivated Actors Are Expanding Access Into OT: Analysis of Kill Lists That Include OT Processes Used With Seven Malware Families

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Kill Lists That Include OT Processes Used With Seven Malware Families

Mandiant Threat Intelligence has researched and written extensively
on the increasing financially motivated threat activity directly
impacting operational technology (OT) networks. Some of this research
is available in our previous blog posts on industrial
post-compromise ransomware and FireEye’s
approach to OT security. While most of the actors behind this
activity likely do not differentiate between IT and OT or have a
particular interest in OT assets, they are driven by the goal of
making money and have demonstrated the skills needed to operate in
these networks. For example, the shift to post-compromise ransomware
deployment highlights the actors’ ability to adapt to more complex environments.

In this blog post we look further into this trend by examining two
different process kill lists containing OT processes which we have
observed deployed alongside a variety of ransomware samples and
families. We think it is likely that these lists were the result of
coincidental asset scanning in victim organizations and not specific
targeting of OT. While this judgement may initially seem like good
news to defenders, this activity still indicates that multiple, very
prolific, financially motivated threat actors are active inside
organizations’ OT—based on the contents of these process kill
lists—with the intent of profiting from the ransom of stolen
information and disrupted services.

Two Unique Process Kill Lists Deployed Alongside Seven Ransomware
Families Include OT Processes

Threat actors often deploy process kill lists alongside or as part
of ransomware to terminate anti-virus products, stop alternative
detection mechanisms, and remove file locks to ensure critical data is
encrypted. As a result, the deployment of these lists increases the
likelihood of a successful attack (MITRE ATT&CK T1489). In post
compromise ransomware attacks, attackers regularly tailor the lists to
include processes that are relevant to the victim’s environment. By
stopping these processes, the attacker makes sure to encrypt data from
critical systems, which may remain unaffected if the process is
currently in use. As the likelihood of crippling critical systems
increases, the target is more likely to suffer impacts on its physical production.

First Process Kill List Has Been Leveraged By At Least Six
Ransomware Families

Mandiant identified samples of at least six ransomware families
(DoppelPaymer, LockerGoga, Maze, MegaCortex, Nefilim and
SNAKEHOSE)—all of which have been associated with high-profile
incidents impacting industrial organizations over the past two
years—that have leveraged a common process kill list containing 1,000+
processes. The list, which we briefly discussed in an earlier blog
post from February 2020, includes a couple dozen processes
related to OT executables—mainly from General Electric Proficy, a
suite used for historians and human-machine interfaces (HMIs). We
note, that while the inclusion of these processes in this kill list
could result in limited loss of view of historical process data, it is
not likely to directly impact the operator’s ability to control the
physical process itself.

Figure 1: Snippets from “kill.bat”
deployed alongside LockerGoga (L) and MegaCortex process kill list (R)

The earliest iteration we identified of the shared kill list was a
batch script deployed alongside LockerGoga (MD5:
34187a34d0a3c5d63016c26346371b54) in January 2019 (Figure 1). Other
iterations of the list we have observed are also hardcoded directly
into the ransomware binaries. The different techniques used to deploy
the process kill list, the use of different malware families, and
slight variations between each list iteration (mainly typos in the
processes, e.g.: a2guard.exea2start.exe; nexe;
proficyclient.exe) indicate that likely more than one actor had
access to the true source of the process kill list. This source could
be for example a post of processes shared on a dark web forum, or an
independent actor sharing the compiled list with other actors.

We think it is likely that the OT processes identified in this list
simply represent the coincidental output of automated process
collection from victim environment(s) and not a targeted effort to
impact OT. This is supported by the relatively limited and specific
selection of OT-related processes, rather than a broader selection of
many vendors and OT-related processes that would have been suggestive
of targeted external research. Regardless, this does not downplay the
significance of the inclusion of OT processes in the list, as it
suggests that sophisticated financially motivated actors, such as
FIN6, have had at least some visibility into a victim’s OT network. As
a result, the actors were able to tailor their malware to impact those
systems, without the explicit intent to target OT assets.

Most types of ransomware attacks in OT environments will result in
the disruption of services and a temporary loss of view into current
and historical process data. However, OT environments impacted by a
ransomware that leverages this kill list and happen to be running one
or more of the processes used by the initial victim(s)—and therefore
are included on the list—may face additional impacts. For example,
historian databases would be more likely to be encrypted, possibly
resulting in loss of historical data. Other impacts could include gaps
in the collection of process data corresponding to the duration of the
outage and temporary loss of access to licensing rights for critical services.

Second List Deployed Alongside CLOP Ransomware Sample Has a Higher
Chance of Impacting OT Systems

Mandiant analyzed a second, entirely unrelated sample of ransomware
(MD5: 3b980d2af222ec909b948b6bbdd46319) from the CLOP family with a
hardcoded list for enumeration and termination of processes that
includes a number of OT strings. The list contains over 1,425
processes, from which at least 150 belong to OT-related software
suites (Figure 2 and Appendix).

Based on our analysis, the CLOP malware family’s process kill list
has grown over time possibly as more processes are scanned during
different compromises. While we do not currently hold enough
information to describe the exact mechanism used by the actor to grow
the list, it appears to have resulted from actor reconnaissance across
multiple victims. We have observed the threat actor employing process
discovery procedures, including running the tasklist utility. This
indicates that the actor scanned for processes in at least one
victim’s OT network(s) before deploying the ransomware.

Figure 2: Subset of processes in observed
CLOP sample

CLOP is also interesting as we have only observed a single unique
and very prolific financially motivated threat actor leveraging the
malware family. The group, who has been active since at least 2016 and
potentially as early as 2014, is known for operating large phishing
campaigns to distribute malware and typically monetizes intrusions
through ransomware deployment. As highlighted by their versatility and
long history in financially motivated intrusions, the actor’s activity
in OT networks is likely no more than an additional step in the
process for monetization. However, the financial motivations of the
actor again do not imply low risk to OT. Instead, our analysis of the
CLOP sample’s kill list indicates that the included processes actually
have greater potential to disrupt OT systems than those included in
the shared list described above.

Unlike the first kill list, the CLOP sample includes a list of
processes that, if stopped, may directly impact the operator’s ability
to both visualize and control production. This is especially true in
the case of some included processes that support HMI and PLC
supervision. Some of the OT processes present in the CLOP sample are
related to the following products:

Table 1: Examples of products related to OT
processes included in identified CLOP kill list

While it is likely the physical processes this software controls
would continue to operate even if the software processes were
terminated unexpectedly, stopping the software processes included in
the CLOP sample’s kill list could result in the loss of view/control
over those physical processes due to the inability of operators to
interact with the equipment. This can be caused not only by the
ransomware’s disruption of intermediary systems, but also by the loss
of access to relevant files on HMIs/EWS required for the operation of
process control and monitoring software–for example configurations or
project files. This could prolong the mean time to recovery (MTTR) of
impacted environments without offline backups. In the CLOP sample
list, we also identified specialized processes for software
application design and testing that may also become corrupted at the
time of encryption.

Process Kill Lists Are Just An Observable Indicating Broader
Financially Motivated Interest In OT

Financially motivated threat actors leverage a large variety of
tactics and techniques to obtain data that they can later use to
generate profits. While financial actors have historically posed
little to no threat to OT systems, the recent uptick in ransomware and
extortion incidents highlights that industrial operations are
increasingly at risk. Although we have not observed any financially
motivated actors explicitly targeting OT systems, our research into
process kill lists deployed with or alongside ransomware samples shows
that at least two sophisticated financial actors have expanded their
access into OT networks during their regular intrusions.

This increasing exposure of OT to financially motivated threat
activity is no surprise, given that TTPs used by cybercriminals
increasingly resemble those employed by sophisticated actors. We have
consistently conveyed this message since at least 2018, when we
publicly discussed the commodity and custom
IT tools leveraged by the TRITON attacker while traversing
through its targets’ networks (Figure 3). The likelihood of
financially motivated actors impacting OT while seeking to monetize
intrusions will continue to rise for the following reasons:

Figure 3: TTPs seen across both IT and OT incidents

• Financially-motivated threat actors moving to a
  post-compromise ransomware model will continue to evolve and find
  ways to reach the most critical systems of organizations as part of
  their mission of monetization. As these actors are mainly driven by
  profits, they are not likely to differentiate between IT and OT
  assets.
• OT organizations will continue to struggle to evolve
  at the same pace as cyber criminals. As a result, small weaknesses
  such as misconfigurations, exposed vulnerabilities or improper
  segmentation will be enough for financial actors to gain access to
  networks in their attempts to profit from intrusions.
• As
  the market for OT solutions continues to incorporate IT services and
  features into broadly adopted products, we expect the convergence of
  technologies to result in a broader attack surface for financial
  threat actors to target.
• The TTPs employed by both
  financial and sophisticated nation-state actors often rely on
  intermediary systems as stepping stones through intrusions. As a
  result, the skills of both groups hold similar potential of reaching
  OT systems even when financial groups may only do so coincidentally
  or as part of their monetization strategy.

Outlook

As OT networks continue to become more accessible to threat actors
of all motivations, security threats that have historically impacted
primarily IT are becoming more commonplace. This normalization of OT
as just another network from the threat actor perspective is
problematic for defenders for many of the reasons discussed above.
This recent threat activity should be taken as a wake-up call for two
main reasons: the various security challenges commonly faced by
organizations to protect OT networks, and the significant consequences
that may arise from security compromises even when they are not
explicitly designed to target production systems. Asset owners need to
look at OT security with the mindset that it is not if you will have a
breach, but when. This shift in thinking will allow defenders to
better prepare to respond when an incident does happen, and can help
reduce the impact of an incident by orders of magnitude.   

Appendix: Selection Of OT Processes From CLOP Kill List