rhysida

Tácticas y técnicas observadas del actor, mapeadas a MITRE ATT&CK (clic para ver la ficha oficial). Útil para priorizar detecciones.

Para detección/bloqueo en tu EDR/SIEM. Fuente: ransomware.live.

Firma de detección defensiva para este grupo (úsala en tu EDR/SIEM). Fuente: ransomware.live.

rule Rhysida_Ransom {
meta:
        author= "Ali Can Gönüllü"
        filetype= "Win64 exe"
        description= "Rhysida 0.1 Ransomware"
strings:
        $ver= {52 68 79 73 69 64 61 2D 30 2E 31}
    $str1= {43 72 69 74 69 63 61 6C 42 72 65 61 63 68 44 65 74 65 63 74 65 64 2E 70 64 66}
    $str2= {43 3A 2F 55 73 65 72 73 2F 50 75 62 6C 69 63 2F 62 67 2E 6A 70 67}
    $str3= {72 68 79 73 69 64 61 66 6F 68 72 68 79 79 32 61 73 7A 69 37 62 6D 33 32 74 6E 6A 61 74 35 78 72 69 36 35 66 6F 70 63 78 6B 64 66 78 68 69 34 74 69 64 73 67 37 63 61 64 2E 6F 6E 69 6F 6E}
    $str4= {63 68 61 63 68 61 32 30}

    $cmd1= {63 6D 64 2E 65 78 65 20 2F 63 20 72 65 67 20 64 65 6C 65 74 65 20 22 48 4B 43 55 5C 43 6F 6E 74 ?? 6F 6C 20 50 61 6E 65 6C 5C 44 65 73 6B 74 6F 70 22 20 2F 76 20 57 61 6C 6C 70 61 70 65 72 20 2F 66}
    $cmd2= {63 6D 64 2E 65 78 65 20 2F 63 20 72 65 67 20 64 65 6C 65 74 65 20 22 48 4B 43 55 5C 43 6F 6E 74 ?? 6F 6C 20 50 61 6E 65 6C 5C 44 65 73 6B 74 6F 70 22 20 2F 76 20 57 61 6C 6C 70 61 70 65 72 53 74 79 6C 65 20 2F 66}
    $cmd2= {63 6D 64 2E 65 78 65 20 2F 63 20 72 65 67 20 61 64 64 20 22 48 4B 43 55 5C 53 6F 66 74 77 61 72 65 5C 4D 69 63 72 6F 73 6F 66 74 5C 57 69 6E 64 6F 77 73 5C 43 75 72 72 65 6E 74 56 65 72 73 69 6F 6E 5C 50 6F 6C 69 63 69 65 73 5C 41 63 74 69 76 65 44 65 73 6B 74 6F 70 22 20 2F 76 20 4E 6F 43 68 61 6E 67 69 6E 67 57 61 6C 6C 50 61 70 65 72 20 2F 74 20 52 45 47 5F 53 5A 20 2F 64 20 31 20 2F 66}
    $cmd3= {63 6D 64 2E 65 78 65 20 2F 63 20 72 65 67 20 61 64 64 20 22 48 4B 43 55 5C 43 6F 6E 74 72 6F 6C 20 50 61 6E 65 6C 5C 44 65 73 6B 74 6F 70 22 20 2F 76 20 57 61 6C 6C 70 61 70 65 72 20 2F 74 20 52 45 47 5F 53 5A 20 2F 64 20 22 43 3A 5C 55 73 65 72 73 5C 50 75 62 6C 69 63 5C 62 67 2E 6A 70 67 22 20 2F 66}
    $cmd4= {63 6D 64 2E 65 78 65 20 2F 63 20 72 65 67 20 61 64 64 20 22 48 4B 4C 4D 5C 53 6F 66 74 77 61 72 65 5C 4D 69 63 72 6F 73 6F 66 74 5C 57 69 6E 64 6F 77 73 5C 43 75 72 72 65 6E 74 56 65 72 73 69 6F 6E 5C 50 6F 6C 69 63 69 65 73 5C 53 79 73 74 65 6D 22 20 2F 76 20 57 61 6C 6C 70 61 70 65 72 20 2F 74 20 52 45 47 5F 53 5A 20 2F 64 20 22 43 3A 5C 55 73 65 72 73 5C 50 75 62 6C 69 63 5C 62 67 2E 6A 70 67 22 20 2F 66}

    
  

condition:
uint16(0) == 0x5A4D and
(
$ver and
4 of ($str*) and
4 of ($cmd*)
)
}


rule Rhysida_Ransomware{
meta:
author= "Venus Chhantel"
filetype= "Win64 exe"
description= "Detecting Rhysida 0.1 Ransomware"
strings:
$version= {52 68 79 73 69 64 61 2D 30 2E 31}


    $string1= {43 72 69 74 69 63 61 6C 42 72 65 61 63 68 44 65 74 65 63 74 65 64 2E 70 64 66}
    $string2= {43 3A 2F 55 73 65 72 73 2F 50 75 62 6C 69 63 2F 62 67 2E 6A 70 67}
    $string3= {72 68 79 73 69 64 61 66 6F 68 72 68 79 79 32 61 73 7A 69 37 62 6D 33 32 74 6E 6A 61 74 35 78 72 69 36 35 66 6F 70 63 78 6B 64 66 78 68 69 34 74 69 64 73 67 37 63 61 64 2E 6F 6E 69 6F 6E}
    $string4= {63 68 61 63 68 61 32 30}
    $string5= {49 6D 6D 65 64 69 61 74 65 20 52 65 73 70 6F 6E 73 65 20 52 65 71 75 69 72 65 64}
    $string6= {54 68 69 73 20 69 73 20 61 6E 20 61 75 74 6F 6D 61 74 65 64 20 61 6C 65 72 74 20 66 72 6F 6D 20 63 79 62 65 72 73 65 63 75 72 69 74 79 20 74 65 61 6D 20 52 68 79 73 69 64 61}

    $cmd1= {63 6D 64 2E 65 78 65 20 2F 63 20 72 65 67 20 64 65 6C 65 74 65 20 22 48 4B 43 55 5C 43 6F 6E 74 ?? 6F 6C 20 50 61 6E 65 6C 5C 44 65 73 6B 74 6F 70 22 20 2F 76 20 57 61 6C 6C 70 61 70 65 72 20 2F 66}
    $cmd2= {63 6D 64 2E 65 78 65 20 2F 63 20 72 65 67 20 64 65 6C 65 74 65 20 22 48 4B 43 55 5C 43 6F 6E 74 ?? 6F 6C 20 50 61 6E 65 6C 5C 44 65 73 6B 74 6F 70 22 20 2F 76 20 57 61 6C 6C 70 61 70 65 72 53 74 79 6C 65 20 2F 66}
    $cmd3= {63 6D 64 2E 65 78 65 20 2F 63 20 72 65 67 20 61 64 64 20 22 48 4B 43 55 5C 53 6F 66 74 77 61 72 65 5C 4D 69 63 72 6F 73 6F 66 74 5C 57 69 6E 64 6F 77 73 5C 43 75 72 72 65 6E 74 56 65 72 73 69 6F 6E 5C 50 6F 6C 69 63 69 65 73 5C 41 63 74 69 76 65 44 65 73 6B 74 6F 70 22 20 2F 76 20 4E 6F 43 68 61 6E 67 69 6E 67 57 61 6C 6C 50 61 70 65 72 20 2F 74 20 52 45 47 5F 53 5A 20 2F 64 20 31 20 2F 66}
    $cmd4= {63 6D 64 2E 65 78 65 20 2F 63 20 72 65 67 20 61 64 64 20 22 48 4B 43 55 5C 43 6F 6E 74 72 6F 6C 20 50 61 6E 65 6C 5C 44 65 73 6B 74 6F 70 22 20 2F 76 20 57 61 6C 6C 70 61 70 65 72 20 2F 74 20 52 45 47 5F 53 5A 20 2F 64 20 22 43 3A 5C 55 73 65 72 73 5C 50 75 62 6C 69 63 5C 62 67 2E 6A 70 67 22 20 2F 66}
    $cmd5= {63 6D 64 2E 65 78 65 20 2F 63 20 72 65 67 20 61 64 64 20 22 48 4B 4C 4D 5C 53 6F 66 74 77 61 72 65 5C 4D 69 63 72 6F 73 6F 66 74 5C 57 69 6E 64 6F 77 73 5C 43 75 72 72 65 6E 74 56 65 72 73 69 6F 6E 5C 50 6F 6C 69 63 69 65 73 5C 53 79 73 74 65 6D 22 20 2F 76 20 57 61 6C 6C 70 61 70 65 72 20 2F 74 20 52 45 47 5F 53 5A 20 2F 64 20 22 43 3A 5C 55 73 65 72 73 5C 50 75 62 6C 69 63 5C 62 67 2E 6A 70 67 22 20 2F 66}
    $cmd6= {63 6D 64 2E 65 78 65 20 2F 63 20 72 65 67 20 61 64 64 20 22 48 4B 4C 4D 5C 53 6F 66 74 77 61 72 65 5C 4D 69 63 72 6F 73 6F 66 74 5C 57 69 6E 64 6F 77 73 5C 43 75 72 72 65 6E 74 56 65 72 73 69 6F 6E 5C 50 6F 6C 69 63 69 65 73 5C 53 79 73 74 65 6D 22 20 2F 76 20 57 61 6C 6C 70 61 70 65 72 53 74 79 6C 65 20 2F 74 20 52 45 47 5F 53 5A 20 2F 64 20 32 20 2F 66}
    $cmd7= {63 6D 64 2E 65 78 65 20 2F 63 20 72 65 67 20 61 64 64 20 22 48 4B 43 55 5C 43 6F 6E 74 72 6F 6C 20 50 61 6E 65 6C 5C 44 65 73 6B 74 6F 70 22 20 2F 76 20 57 61 6C 6C 70 61 70 65 72 53 74 79 6C 65 20 2F 74 20 52 45 47 5F 53 5A 20 2F 64 20 32 20 2F 66}
    $cmd8= {72 75 6E 64 6C 6C 33 32 2E 65 78 65 20 75 73 65 72 33 32 2E 64 6C 6C 2C 55 70 64 61 74 65 50 65 72 55 73 65 72 53 79 73 74 65 6D 50 61 72 61 6D 65 74 65 72 73}
    $cmd9= {63 6D 64 2E 65 78 65 20 2F 63 20 73 74 61 72 74 20 70 6F 77 65 72 73 68 65 6C 6C 2E 65 78 65 20 2D 57 69 6E 64 6F 77 53 74 79 6C 65 20 48 69 64 64 65 6E 20 2D 43 6F 6D 6D 61 6E 64 20 53 6C 65 65 70 20 2D 4D 69 6C 6C 69 73 65 63 6F 6E 64 73 20 ?? ?? ?? 3B}
    $cmd10= {52 65 6D 6F 76 65 2D 49 74 65 6D 20 2D 46 6F 72 63 65 20 2D 50 61 74 68 20 22}
    $cmd11= {22 20 2D 45 72 72 6F 72 41 63 74 69 6F 6E 20 53 69 6C 65 6E 74 6C 79 43 6F 6E 74 69 6E 75 65 3B}

    
condition:
uint16(0) == 0x5A4D and
(
$version and
4 of ($string*) and
5 of ($cmd*)
)
}

rule RhysidaRansomware {
	meta:
		description = "rule to detect Rhysida Ransomware"
		author = "ShadowStackRe.com"
		date = "2023-12-12"
		Rule_Version = "v1"
		malware_type = "ransomware"
		malware_family = "Rhysida"
		License = "MIT License, https://opensource.org/license/mit/"
	strings:
		$strShadowCopy = " vssadmin.exe Delete Shadows"
		$strRhsyida01 = "Rhysida-0.1"
		$strRhysida = "rhysida"
		$strRegKey1 = "cmd.exe /c reg delete \"HKCU\\Contol Panel\\Desktop"
		$strRegKey2 = "Policies\\ActiveDesktop\" /v NoChangingWallPaper"
		$strRunDll32 = "rundll32.exe user32.dll,UpdatePerUserSystemParameters"
		$strPDF = "CriticalBreachDetected.pdf"
	condition:
		all of them
}

Critical Breach Detected - Immediate Response Required
Dear company,
This is an automated alert from cybersecurity team Rhysida. An unfortunate situation has arisen - your digital ecosystem has been compromised, and a substantial amount of confidential data has been exfiltrated from your network. The potential ramifications of this could be dire, including the sale, publication, or distribution of your data to competitors or media outlets. This could inflict significant reputational and financial damage.
However, this situation is not without a remedy.
Our team has developed a unique key, specifically designed to restore your digital security. This key represents the first and most crucial step in recovering from this situation. To utilize this key, visit our secure portal: [redactado] with your secret key [snip]
It's vital to note that any attempts to decrypt the encrypted files independently could lead to permanent data loss. We strongly advise against such actions.
Time is a critical factor in mitigating the impact of this breach. With each passing moment, the potential damage escalates. Your immediate action and full cooperation are required to navigate this scenario effectively.
Rest assured, our team is committed to guiding you through this process. The journey to resolution begins with the use of the unique key. Together, we can restore the security of your digital environment.
Best regards

• https://www.ransomware.live/group/rhysida

• Government & Defense
  8
• Professional Services
  7
• Healthcare
  6
• Other
  4