Trellix Insights: HelloKitty Ransomware Targeting Linux VMware ESXi Servers
Technical Articles ID:
KB94923
Last Modified: 2022-09-07 09:47:21 Etc/GMT
Last Modified: 2022-09-07 09:47:21 Etc/GMT
Environment
IMPORTANT: This Knowledge Base article discusses a specific threat that is being automatically tracked by Trellix Insights technology. The content is intended for use by Trellix Insights users, but is provided for general knowledge to all customers. Contact us for more information about Trellix Insights.
Summary
HelloKitty has been in operation since November 2020. The ransomware gang recently released a Linux variant that targets VMware's ESXi virtual machine platform for maximum damage. As the enterprise increasingly moves to virtual machines for easier backup and resource management, ransomware gangs are evolving their tactics to create Linux encryptors that target these servers. VMware ESXi is one of the most popular enterprise virtual machine platforms. Over the past year, there has been an increasing number of ransomware gangs releasing Linux encryptors targeting this platform. While ESXi isn't strictly for Linux as it uses its own custom kernel, it does share similar characteristics, including the ability to run ELF64 Linux executables.
Our Threat Research team gathers and analyzes information from multiple open and closed sources before disseminating intelligence reports. This ransomware variant was researched by the MalwareHunterTeam and shared publicly.
How to use this article:
- If a Threat Hunting table has been created, use the rules contained to search for malware related to this campaign.
- Review the product detection table and confirm that your environment is at least on the specified content version.
To download the latest content versions, go to the Security Updates page. - Scroll down and review the "Product Countermeasures" section of this article. Consider implementing them if they are not already in place.
- Review
KB91836 - Countermeasures for entry vector threats . - Review KB87843 - Dynamic Application Containment rules and best practices.
- Review KB82925 - Identify what rule corresponds to an Adaptive Threat Protection and Threat Intelligence Exchange event.
meta: description = "rule to detect Linux variant of the Hello Kitty Ransomware" author = "Christiaan @ ATR" date = "2021-07-19" Rule_Version = "v1" malware_type = "ransomware" malware_family = "Ransom:Linux/HelloKitty" hash1 = "ca607e431062ee49a21d69d722750e5edbd8ffabcb54fa92b231814101756041" hash2 = "556e5cb5e4e77678110961c8d9260a726a363e00bf8d278e5302cb4bfccc3eed" strings: $v1 = "esxcli vm process kill -t=force -w=%d" fullword ascii $v2 = "esxcli vm process kill -t=hard -w=%d" fullword ascii $v3 = "esxcli vm process kill -t=soft -w=%d" fullword ascii $v4 = "error encrypt: %s rename back:%s" fullword ascii $v5 = "esxcli vm process list" fullword ascii $v6 = "Total VM run on host:" fullword ascii $v7 = "error lock_exclusively:%s owner pid:%d" fullword ascii $v8 = "Error open %s in try_lock_exclusively" fullword ascii $v9 = "Mode:%d Verbose:%d Daemon:%d AESNI:%d RDRAND:%d " fullword ascii $v10 = "pthread_cond_signal() error" fullword ascii $v11 = "ChaCha20 for x86_64, CRYPTOGAMS by condition: ( uint16(0) == 0x457f and filesize < 200KB and ( 8 of them ) ) or ( all of them ) } |
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meta: description = "YARA rule HelloKitty linux variant ransomware" reference = "https://soolidsnake.github.io/2021/07/17/hellokitty_linux.html" author = "@soolidsnakee" date = "2021-07-17" strings: $str1 = ".crypt" $str2 = ".README_TO_RESTORE" $str5 = "switch to daemon" $str6 = "esxcli vm process kill -t=hard -w=%d" $str7 = "work.log" $str8 = "m:vdekc:" condition: all of ($str*) } |
This Knowledge Base article discusses a specific threat that's being tracked. The list of IOCs will change over time; check Trellix Insights for the latest IOCs.
Campaign IOC
Type | Value |
Minimum Content Versions
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Detection Summary
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Aggressive set of Manual Rules to improve protection to block this campaign:
IMPORTANT: Always follow best practices when you enable new rules and signatures.
When you implement new rules or signatures, always set them to Report mode first and check the alerts generated. Resolve any issues that arise and then set the rules to Block. This step mitigates against triggering false positives and allows you to refine your configuration.
For more information, see KB87843 - List of and best practices for Endpoint Security Dynamic Application Containment rules.
Host Intrusion Prevention:
Rule ID: 1020 Windows Agent Shielding - File Access
Rule ID: 6010 Generic Application Hooking Protection
Rule ID: 2806 Attempt to create a hardlink to a file
Rule ID: 1148 CMD Tool Access by a Network Aware Application
Rule ID: 412 Double File Extension Execution