Cisco Threat Research Blog

Threat intelligence for Cisco Products

We detect, analyze, and protect customers from both known and unknown emerging threats

Threat Roundup for November 13 to November 20

Today, Talos is publishing a glimpse into the most prevalent threats we’ve observed between November 13 and November 20. As with previous roundups, this post isn’t meant to be an in-depth analysis. Instead, this post will summarize the threats we’ve observed by highlighting key behavioral characteristics, indicators of compromise, and discussing how our customers are automatically protected from these threats.

As a reminder, the information provided for the following threats in this post is non-exhaustive and current as of the date of publication. Additionally, please keep in mind that IOC searching is only one part of threat hunting. Spotting a single IOC does not necessarily indicate maliciousness. Detection and coverage for the following threats is subject to updates, pending additional threat or vulnerability analysis. For the most current information, please refer to your Firepower Management Center, Snort.org, or ClamAV.net.

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Reference

20201120-tru.json – this is a JSON file that includes the IOCs referenced in this post, as well as all hashes associated with the cluster. The list is limited to 25 hashes in this blog post. As always, please remember that all IOCs contained in this document are indicators, and that one single IOC does not indicate maliciousness. See the Read More link above for more details.

Back from vacation: Analyzing Emotet’s activity in 2020

By Nick Biasini, Edmund Brumaghin, and Jaeson Schultz.

Emotet is one of the most heavily distributed malware families today. Cisco Talos observes large quantities of Emotet emails being sent to individuals and organizations around the world on an almost daily basis. These emails are typically sent automatically by previously infected systems   attempting to infect new systems with Emotet to continue growing the size of the botnets associated with this threat. Emotet is often the initial malware that is delivered as part of a multi-stage infection process and is not targeted in nature. Emotet has impacted systems in virtually every country on the planet over the past several years and often leads to high impact security incidents as the network access it provides to adversaries enables further attacks, such as big-game hunting and double-extortion ransomware attacks.

Cisco Talos obtained ownership of several domains that Emotet uses to send SMTP communications. We leveraged these domains to sinkhole email communications originating from the Emotet botnets for the purposes of observing the characteristics of these email campaigns over time and to gain additional insight into the scope and profile of Emotet infections and the organizations being impacted by this threat. Emotet has been observed taking extended breaks over the past few years, and 2020 was no exception. Let’s take a look at what Emotet has been up to in 2020 and the effect it’s had on the internet as a whole.

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Nibiru ransomware variant decryptor

Nikhil Hegde developed this tool.

Weak encryption

The Nibiru ransomware is a .NET-based malware family. It traverses directories in the local disks, encrypts files with Rijndael-256 and gives them a .Nibiru extension. Rijndael-256 is a secure encryption algorithm. However, Nibiru uses a hard-coded string “Nibiru” to compute the 32-byte key and 16-byte IV values. The decryptor program leverages this weakness to decrypt files encrypted by this variant.

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Threat Roundup for November 6 to November 13

Today, Talos is publishing a glimpse into the most prevalent threats we’ve observed between November 6 and November 13. As with previous roundups, this post isn’t meant to be an in-depth analysis. Instead, this post will summarize the threats we’ve observed by highlighting key behavioral characteristics, indicators of compromise, and discussing how our customers are automatically protected from these threats.

As a reminder, the information provided for the following threats in this post is non-exhaustive and current as of the date of publication. Additionally, please keep in mind that IOC searching is only one part of threat hunting. Spotting a single IOC does not necessarily indicate maliciousness. Detection and coverage for the following threats is subject to updates, pending additional threat or vulnerability analysis. For the most current information, please refer to your Firepower Management Center, Snort.org, or ClamAV.net.

Read More

Reference

20201113-tru.json  – this is a JSON file that includes the IOCs referenced in this post, as well as all hashes associated with the cluster. The list is limited to 25 hashes in this blog post. As always, please remember that all IOCs contained in this document are indicators, and that one single IOC does not indicate maliciousness. See the Read More link above for more details.

CRAT wants to plunder your endpoints

By Asheer Malhotra.

  • Cisco Talos has observed a new version of a remote access trojan (RAT) family known as CRAT.
  • Apart from the prebuilt RAT capabilities, the malware can download and deploy additional malicious plugins on the infected endpoint.
  • One of the plugins is a ransomware known as “Hansom.”
  • CRAT has been attributed to the Lazarus APT Group in the past.
  • The RAT consists of multiple obfuscation techniques to hide strings, API names, command and control (C2) URLs and instrumental functions, along with static detection evasion.
  • The attack also employs a multitude of anti-infection checks to evade sandbox based detection systems.

What’s new?

Cisco Talos has recently discovered a new version of the CRAT malware family. This version consists of multiple RAT capabilities, additional plugins and a variety of detection-evasion techniques. In the past, CRAT has been attributed to the Lazarus Group, the malicious threat actors behind multiple cyber campaigns, including attacks against the entertainment sector.

Indicators and tactics, techniques and procedures (TTPs) discovered by this investigation resemble those of the Lazarus Group.

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Threat Roundup for October 30 to November 6

Today, Talos is publishing a glimpse into the most prevalent threats we’ve observed between October 30 and November 6. As with previous roundups, this post isn’t meant to be an in-depth analysis. Instead, this post will summarize the threats we’ve observed by highlighting key behavioral characteristics, indicators of compromise, and discussing how our customers are automatically protected from these threats.

As a reminder, the information provided for the following threats in this post is non-exhaustive and current as of the date of publication. Additionally, please keep in mind that IOC searching is only one part of threat hunting. Spotting a single IOC does not necessarily indicate maliciousness. Detection and coverage for the following threats is subject to updates, pending additional threat or vulnerability analysis. For the most current information, please refer to your Firepower Management Center, Snort.org, or ClamAV.net.

Read More

Reference

20201106-tru.json  – this is a JSON file that includes the IOCs referenced in this post, as well as all hashes associated with the cluster. The list is limited to 25 hashes in this blog post. As always, please remember that all IOCs contained in this document are indicators, and that one single IOC does not indicate maliciousness. See the Read More link above for more details.

Threat Roundup for October 23 to October 30

Today, Talos is publishing a glimpse into the most prevalent threats we’ve observed between October 23 and October 30. As with previous roundups, this post isn’t meant to be an in-depth analysis. Instead, this post will summarize the threats we’ve observed by highlighting key behavioral characteristics, indicators of compromise, and discussing how our customers are automatically protected from these threats.

As a reminder, the information provided for the following threats in this post is non-exhaustive and current as of the date of publication. Additionally, please keep in mind that IOC searching is only one part of threat hunting. Spotting a single IOC does not necessarily indicate maliciousness. Detection and coverage for the following threats is subject to updates, pending additional threat or vulnerability analysis. For the most current information, please refer to your Firepower Management Center, Snort.org, or ClamAV.net.

Read More

Reference

20201030-tru.json  – this is a JSON file that includes the IOCs referenced in this post, as well as all hashes associated with the cluster. The list is limited to 25 hashes in this blog post. As always, please remember that all IOCs contained in this document are indicators, and that one single IOC does not indicate maliciousness. See the Read More link above for more details.

Cisco Talos Advisory on Adversaries Targeting the Healthcare and Public Health Sector

Background

Cisco Talos has become aware that an adversary is leveraging Trickbot banking trojan and Ryuk ransomware to target U.S. hospitals and healthcare providers at an increasing rate. Security journalists reported on October 28, 2020 that the adversary was preparing to encrypt systems at “potentially hundreds” of medical centers and hospitals, based on a tip from a researcher who had been monitoring communications for the threat actor. On October 28 and 29, these claims were supported by the reports of six U.S. hospitals being compromised with Ryuk in the span of 24 hours.
CISA, the FBI, and HHS also confirmed this activity targeting the Healthcare and Public Health Sector, releasing a joint advisory on October 28, 2020. The advisory stated that the Ryuk actors were using Trickbot to target the industry and that the activity posed an “increased and imminent” threat. They also published technical indicators for both Trickbot and Ryuk.
Talos has years of experience dealing with Trickbot, Ryuk, and other tools used by the adversary. We are currently supporting customers who are affected and working hand-in-hand with federal law enforcement to support their investigations.  We are also supporting other law enforcement and federal agencies as well.
If you have a customer that has been impacted by an attack, ransomware or otherwise, the first course of action is to engage Cisco Talos Incident Response Services (CTIR).
For emergencies, call 1-844-831-7715 to reach the Technical Assistance Center (TAC), who will then put you in touch with members of CTIR who are on call. Account managers can also email IRSalesSupport@cisco.com and visit http://go2.cisco.com/CTIRSales.

DoNot’s Firestarter abuses Google Firebase Cloud Messaging to spread

  • The newly discovered Firestarter malware uses Google Firebase Cloud Messaging to notify its authors of the final payload location.
  • Even if the command and control (C2) is taken down, the DoNot team can still redirect the malware to another C2 using Google infrastructure.
  • The approach in the final payload upload denotes a highly personalized targeting policy.

What’s new? The DoNot APT group is making strides to experiment with new methods of delivery for their payloads. They are using a legitimate service within Google’s infrastructure which makes it harder for detection across a users network.

How did it work? Users are lured to install a malicious app on their mobile device. This malicious app then contains additional malicious code which attempts to download a payload based on information obtained from the compromised device. This ensures only very specific devices are delivered the malicious payload.

So what? Innovation across APT Groups is not unheard of and this shouldn’t come as a huge surprise that a group continues to modify their operations to ensure they are as stealth as can be. This should be another warning sign to folks in geo-politically “hot” regions that it is entirely possible that you can become a victim of a highly motivated group.

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