Iran's COBALT MIRAGE Threat Group Behind Ransomware Attacks in the USA

Iran’s COBALT MIRAGE Threat Group Behind Ransomware Attacks in US

Cobalt Mirage is an Irani threat group believed to be linked to the Iranian Cobalt Illusion threat group, whereas Cobalt Mirage’s activities have been reported as TunnelVision and Phosphorus.

SecureWorks® Counter Threat Unit™ (CTU) researchers are investigating an Irani threat group known as the Cobalt Mirage group. This group first surfaced in June 2020 and is linked to another Irani threat group Cobalt Illusion, also known as Charming Kitten, Phosphorus, APT35, and Newscaster.

The group primarily uses phishing campaigns to gain access to networks. Researchers suspect that the two groups are interconnected and might share access and tradecraft.

It is worth noting that previously, Charming Kitten was also accused of its involvement in some highly sophisticated social engineering attacks including bypassing Gmail and Yahoo’s 2FA (Two-Factor Authentication (2FA) in December 2018.

Furthermore, Charming Kitten was the talk of the town in March 2019 when Microsoft seized 99 websites used by Iranian hackers for large-scale phishing attacks. In July 2020, the same group exposed 40GB of videos exposing its entire modus operandi.

Cobalt Mirage Attack Tactics

Based on information obtained via incident response activities and public reporting, the researchers identified two clusters of Cobalt Mirage attacks, labeled Cluster A and Cluster B. 

According to researchers, threat actors used DiskCryptor and BitLocker in Cluster A for conducting ransomware attacks that are mainly profit-driven. On the other hand, Cluster B entails targeted intrusions to invade a network and collect intelligence. But sometimes, Cluster B attacks may also involve ransomware in selected cases.

Iran's COBALT MIRAGE Threat Group Behind Ransomware Attacks in the USA
COBALT MIRAGE’s attack vector (Image: SecureWorks)

Primary Targets of Cobalt Mirage

According to SecureWorks’s blog post published on May 12th, Cobalt Mirage’s victims are primarily organizations in the USA, Australia, Europe, and Israel. The group mainly uses file-encrypting ransomware to target its victims.

Some of its previous campaigns include the scan-and-exploit attack against Microsoft Exchange Servers and exploiting the ProxyShell vulnerabilities in March 2022 to access a US local government network.

The group also targeted a philanthropic organization in the USA in January 2022. Research reveals that the group has limited ability to capitalize on the access they gain to a network and use it for financial gains or intelligence data collection.

How does Cobalt Mirage Attack its Victims?

Research revealed that Cobalt Mirage scans internet-exposed servers to detect vulnerable servers and identify initial access routes. They often look for flaws in Microsoft Exchange servers and Fortinet appliances.

In 2021, SecureWorks’ blog post revealed that the threat group scanned ports 4443, 8443, and 10443 to find flaws in devices vulnerable to FortiOS vulnerabilities (CVE-2018-13379, CVE-2020-12812, and CVE-2019-5591).

In September 2021, they targeted the MS Exchange servers and deployed the Fast Reverse Proxy Client by exploiting the ProxyShell vulnerabilities (CVE-2021-34473, CVE-2021-34523, and CVE-2021-31207) to enable access to vulnerable devices.

Once they identify a loophole, they drop web shells and use them as a conduit for lateral movement across the network and launch the ransomware. They complete their attack with a rather unusual way of sending ransom notes, which they send to a local printer.

This note contains the email address and Telegram account details for victims to contact the attacker. However, researchers couldn’t identify how the encryption feature is triggered. The group uses publicly available encryption tools for launching ransomware attacks.

Iran's COBALT MIRAGE Threat Group Behind Ransomware Attacks in the USA
COBALT MIRAGE’s ransom note (Image: SecureWorks)

“CTU researchers recommend that organizations use available controls to review and restrict access using the indicators listed in Table 1. Note that IP addresses can be reallocated. The domains and IP addresses may contain malicious content, so consider the risks before opening them in a browser.”

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