Threat Signal Report

Magniber Ransomware Delivered to South Korean Victims Through PrintNightmare Vulnerability

Description

FortiGuard Labs is aware of a report that the Magniber ransomware is delivered to the victims in South Korea by exploiting the PrintNightmare vulnerability for which Microsoft released an emergency patch on July 6th, 2021. Delivery of the Magniber payload onto South Korean victims comes as no surprise as the ransomware is known to solely target South Korean users back in 2017 through the Magnitude exploit kit.

What is PrintNightmare?

PrintNightmare is a name for a remote code execution vulnerability affecting Microsoft Windows Print Spooler, which Microsoft released an out-of-band patch on July 6th, 2021. Successfully exploiting PrintNightmare allows the attacker to run arbitrary code with SYSTEM privileges.

FortiGuard Labs previously published a Threat Signal for PrintNightmare. See link to "#PrintNightmare Zero Day Remote Code Execution Vulnerability" in the Appendix.

Why is the Incident Significant?

While the patch is already out for PrintNightmare, this is still significant as Windows Print Spooler is enabled by default on all Windows systems and a Proof-of-Concept code to exploit the vulnerability was briefly available online.

The PrintNightmare vulnerability is considered severe enough to prompt Microsoft to release an out-of-band patch on July 6th, 2021. Since it's only been just over 30 days after the patch was released, there may still be a lot of unpatched machines in the wild.

Who were the Targets of the Attack?

According to security vendor Crowd Strike, Magniber ransomware gang targeted users in South Korea.

What is Magniber ransomware?

Magniber ransomware is a malware that encrypts files on the compromised system and demands the victim to pay ransom in order to recover the encrypted files.

Upon infection, the victim is instructed to visit the threat actor's Web page using TOR browser.

What is the Status of Coverage?

FortiGuard Labs provides the following AV coverage against this attack:

W64/Injector.FR!tr

Malicious_Behavior.SB

W32/Encoder.NCX!tr

FortiGuard Labs has IPS coverage in place for this vulnerability and known proof of concept code as (definitions version 18.109):

MS.Windows.Print.Spooler.AddPrinterDriver.Privilege.Escalation

Any Other Suggested Mitigation?

The potential for damage to daily operations, reputation, and unwanted release of data, the disruption of business operations, etc. is apparent, and because of this it is important to keep all AV and IPS signatures up to date. It is also important to ensure that all known vendor vulnerabilities within an organization are addressed once available, and updated on a regular basis to protect against attackers establishing a foothold within a network.