rule SUSP_ScheduledTasks_Nimbus_Manticore_Persistence_May26 {
   meta:
      description = "Detects scheduled task used for persistence by Nimbus Manticore (UNC1549). The task is used to persistenly load a custom implant that features data exfiltration and remote control capabilities."
      author = "Jonathan Peters (Nextron Systems)"
      date = "2026-05-27"
      reference = "https://www.nextron-systems.com/2026/06/01/detecting-nimbus-manticore-and-their-sideloading-infection-chains/"
      score = 75
   strings:
      $a0 = "<Task version=" wide
      $a1 = "xmlns=\"http://schemas.microsoft.com/windows/" wide

      $x1 = "<Arguments>doit" wide
   condition:
      uint16(0) == 0xfeff
      and all of them
}

rule MAL_APT_Nimbus_Manticore_Stager_May26 {
   meta:
      description = "Detects .NET based stager using AppDomain Hijacking observed to be used by Nimbus Manticore (UNC1549). The stager drops another payload and establishes persistence via scheduled task."
      author = "Jonathan Peters (Nextron Systems)"
      date = "2026-05-20"
      reference = "https://www.nextron-systems.com/2026/06/01/detecting-nimbus-manticore-and-their-sideloading-infection-chains/"
      hash = "eee657ffdb2af8ed6412221e7d5fbf4f5742f2ac2c88f43f12db46af0697de71"
      score = 80
   strings:
      $x1 = "MyCompany-Product-TOTP-Salt-2024!@#$" wide fullword
      $x2 = "TOTPGuardRunner" ascii fullword
      $x3 = "\\AppDomainInjection-metlifeScenario\\TOTP" ascii

      $sa1 = "EncData" ascii fullword
      $sa2 = "DecryptAndSaveToDesktop" ascii fullword
      $sa3 = "CopyHelloToDesktop" ascii fullword

      $sb1 = "doit" wide fullword
      $sb2 = "DailyTrigger" wide fullword
      $sb3 = "GetTypeFromCLSID" ascii
      $sb4 = "yyyy-MM-ddTHH:mm:ss" wide fullword
   condition:
      uint16(0) == 0x5a4d
      and
      (
         1 of ($x*)
         or all of ($sa*)
         or all of ($sb*)
      )
}

rule MAL_APT_Nimbus_Manticore_Agent_May26 {
   meta:
      description = "Detects Nimbus Manticore (UNC1549) agent implant featuring data exfiltration and remote control."
      author = "Jonathan Peters (Nextron Systems)"
      date = "2026-05-28"
      reference = "https://www.nextron-systems.com/2026/06/01/detecting-nimbus-manticore-and-their-sideloading-infection-chains/"
      hash = "dfa1e3137a032ee8561a1cd5e1a0f71a10bebb36aef7c336c878638a9c1239ee"
      score = 80
   strings:
      $a1 = "Chrome/146.0.0.0 Safari/537.36" wide
      $a2 = ".azurewebsites.net" wide

      $s1 = "/agent/poll?token=" wide fullword
      $s2 = "/agent/init" wide fullword
      $s3 = "/agent/result" wide fullword
   condition:
      uint16(0) == 0x5a4d
      and 1 of ($a*) 
      and 1 of ($s*)
      or 3 of them
}

rule SUSP_Nimbus_Manticore_PDF_Indicators_May26 {
   meta:
      description = "Detects inidcators found in PDF files created by Nimbus Manticore (UNC1549). The PDF files usually contain fake job offers or descriptions to lure victims into installing malware."
      author = "Jonathan Peters (Nextron Systems)"
      date = "2026-05-25"
      reference = "https://www.nextron-systems.com/2026/06/01/detecting-nimbus-manticore-and-their-sideloading-infection-chains/"
      hash = "620c51f4376cb79f0109c21971c28661418ae50b119585e3ffdb8011189fcb7b"
      score = 70
   strings:
      $op = { 3C 3C 2F 41 75 74 68 6F 72 28 4A 65 72 72 79 29 20 2F 43 72 65 61 74 6F 72 28 FE FF 00 4D 00 69 00 63 00 72 00 6F 00 73 00 6F 00 66 00 74 00 AE 00 20 00 57 00 6F 00 72 00 64 00 20 00 4C 00 54 00 53 00 43 29 }
   condition:
      1 of them
}