SUSP_Doc_RTF_OLE2Link_EMAIL_Jun22

rule SUSP_Doc_RTF_OLE2Link_EMAIL_Jun22 {
   meta:
      description = "Detects a suspicious pattern in RTF files which downloads external resources inside e-mail attachments"
      author = "Christian Burkard"
      date = "2022-06-01"
      reference = "Internal Research"
      hash = "4abc20e5130b59639e20bd6b8ad759af18eb284f46e99a5cc6b4f16f09456a68"
      score = 75
      id = "48cde505-3ce4-52ef-b338-0c08ac4f63de"
   strings:
      /* \objdata" */
      $sa1 = "XG9iamRhdG" ascii
      $sa2 = "xvYmpkYXRh" ascii
      $sa3 = "cb2JqZGF0Y" ascii

      /* OLE2Link */
      $sb1 = "NGY0YzQ1MzI0YzY5NmU2Y" ascii
      $sb2 = "RmNGM0NTMyNGM2OTZlNm" ascii
      $sb3 = "0ZjRjNDUzMjRjNjk2ZTZi" ascii
      $sb4 = "NEY0QzQ1MzI0QzY5NkU2Q" ascii
      $sb5 = "RGNEM0NTMyNEM2OTZFNk" ascii
      $sb6 = "0RjRDNDUzMjRDNjk2RTZC" ascii

      /* docfile magic - doc file albilae */
      $sc1 = "ZDBjZjExZTBhMWIxMWFlM" ascii
      $sc2 = "QwY2YxMWUwYTFiMTFhZT" ascii
      $sc3 = "kMGNmMTFlMGExYjExYWUx" ascii
      $sc4 = "RDBDRjExRTBBMUIxMUFFM" ascii
      $sc5 = "QwQ0YxMUUwQTFCMTFBRT" ascii
      $sc6 = "EMENGMTFFMEExQjExQUUx" ascii

      /* http:// */
      $x1 = "NjgwMDc0MDA3NDAwNzAwMDNhMDAyZjAwMmYwM" ascii
      $x2 = "Y4MDA3NDAwNzQwMDcwMDAzYTAwMmYwMDJmMD" ascii
      $x3 = "2ODAwNzQwMDc0MDA3MDAwM2EwMDJmMDAyZjAw" ascii
      $x4 = "NjgwMDc0MDA3NDAwNzAwMDNBMDAyRjAwMkYwM" ascii
      $x5 = "Y4MDA3NDAwNzQwMDcwMDAzQTAwMkYwMDJGMD" ascii
      $x6 = "2ODAwNzQwMDc0MDA3MDAwM0EwMDJGMDAyRjAw" ascii
      /* https:// */
      $x7 = "NjgwMDc0MDA3NDAwNzAwMDczMDAzYTAwMmYwMDJmMD" ascii
      $x8 = "Y4MDA3NDAwNzQwMDcwMDA3MzAwM2EwMDJmMDAyZjAw" ascii
      $x9 = "2ODAwNzQwMDc0MDA3MDAwNzMwMDNhMDAyZjAwMmYwM" ascii
      $x10 = "NjgwMDc0MDA3NDAwNzAwMDczMDAzQTAwMkYwMDJGMD" ascii
      $x11 = "Y4MDA3NDAwNzQwMDcwMDA3MzAwM0EwMDJGMDAyRjAw" ascii
      $x12 = "2ODAwNzQwMDc0MDA3MDAwNzMwMDNBMDAyRjAwMkYwM" ascii
      /* ftp:// */
      $x13 = "NjYwMDc0MDA3MDAwM2EwMDJmMDAyZjAw" ascii
      $x14 = "Y2MDA3NDAwNzAwMDNhMDAyZjAwMmYwM" ascii
      $x15 = "2NjAwNzQwMDcwMDAzYTAwMmYwMDJmMD" ascii
      $x16 = "NjYwMDc0MDA3MDAwM0EwMDJGMDAyRjAw" ascii
      $x17 = "Y2MDA3NDAwNzAwMDNBMDAyRjAwMkYwM" ascii
      $x18 = "2NjAwNzQwMDcwMDAzQTAwMkYwMDJGMD" ascii
      /* TODO: more protocols */
   condition:
      filesize < 10MB
      and 1 of ($sa*)
      and 1 of ($sb*)
      and 1 of ($sc*)
      and 1 of ($x*)
}

rule SUSP_DOC_RTF_ExternalResource_EMAIL_Jun22 {
   meta:
      description = "Detects a suspicious pattern in RTF files which downloads external resources as seen in CVE-2022-30190 / Follina exploitation inside e-mail attachment"
      author = "Christian Burkard"
      date = "2022-06-01"
      reference = "https://doublepulsar.com/follina-a-microsoft-office-code-execution-vulnerability-1a47fce5629e"
      score = 70
      id = "3ddc838c-8520-5572-9652-8cb823f83e27"
   strings:
      /* <Relationships */
      $sa1 ="PFJlbGF0aW9uc2hpcH" ascii
      $sa2 ="xSZWxhdGlvbnNoaXBz" ascii
      $sa3 ="8UmVsYXRpb25zaGlwc" ascii
      /* TargetMode="External" */
      $sb1 ="VGFyZ2V0TW9kZT0iRXh0ZXJuYWwi" ascii
      $sb2 ="RhcmdldE1vZGU9IkV4dGVybmFsI" ascii
      $sb3 ="UYXJnZXRNb2RlPSJFeHRlcm5hbC" ascii
      /* .html!" */
      $sc1 ="Lmh0bWwhI" ascii
      $sc2 ="5odG1sIS" ascii
      $sc3 ="uaHRtbCEi" ascii
   condition:
      filesize < 400KB
      and 1 of ($sa*)
      and 1 of ($sb*)
      and 1 of ($sc*)
}

rule SUSP_Msdt_Artefact_Jun22_2 {
   meta:
      description = "Detects suspicious pattern in msdt diagnostics log (e.g. CVE-2022-30190 / Follina exploitation)"
      author = "Christian Burkard"
      date = "2022-06-01"
      modified = "2022-07-29"
      reference = "https://twitter.com/nas_bench/status/1531718490494844928"
      score = 75
      id = "aa2a4bd7-2094-5652-a088-f58d0c7d3f62"
   strings:
      $a1 = "<ScriptError><Data id=\"ScriptName\" name=\"Script\">TS_ProgramCompatibilityWizard.ps1" ascii

      $x1 = "/../../" ascii
      $x2 = "$(Invoke-Expression" ascii
      $x3 = "$(IEX(" ascii nocase
   condition:
      uint32(0) == 0x6D783F3C /* <?xm */
      and $a1
      and 1 of ($x*)
}