EXPL_LOG_ProxyNotShell_PowerShell_Proxy_Log_Dec22_1

rule EXPL_LOG_ProxyNotShell_PowerShell_Proxy_Log_Dec22_1 {
   meta:
      description = "Detects traces of exploitation activity in relation to ProxyNotShell MS Exchange vulnerabilities CVE-2022-41040 and CVE-2022-41082"
      author = "Florian Roth (Nextron Systems)"
      reference = "https://www.crowdstrike.com/blog/owassrf-exploit-analysis-and-recommendations/"
      date = "2022-12-22"
      modified = "2023-01-26"
      score = 70
      id = "5af3ae70-8897-593f-a413-82ca1d1ba961"
   strings:
      $re1 = /,\/[Pp][Oo][Ww][Ee][Rr][Ss][Hh][Ee][Ll][Ll][^\n]{0,50},Kerberos,true,[^\n]{0,50},200,0,,,,[^\n]{0,2000};OnEndRequest\.End\.ContentType=application\/soap\+xml charset UTF-8;S:ServiceCommonMetadata\.HttpMethod=POST;/ ascii wide

      // based on filters found in CrowdStrikes script https://github.com/CrowdStrike/OWASSRF/blob/main/Rps_Http-IOC.ps1
      $fp1 = "ClientInfo" ascii wide fullword
      $fp2 = "Microsoft WinRM Client" ascii wide fullword
      $fp3 = "Exchange BackEnd Probes" ascii wide fullword
   condition:
      $re1 and not 1 of ($fp*)
}