WEBSHELL_ASPX_SimpleSeeSharp

rule WEBSHELL_ASPX_SimpleSeeSharp : Webshell Unclassified {
   meta:
      author = "threatintel@volexity.com"
      date = "2021-03-01"
      description = "A simple ASPX Webshell that allows an attacker to write further files to disk."
      hash = "893cd3583b49cb706b3e55ecb2ed0757b977a21f5c72e041392d1256f31166e2"
      reference = "https://www.volexity.com/blog/2021/03/02/active-exploitation-of-microsoft-exchange-zero-day-vulnerabilities/"
      id = "469fdf5c-e09e-5d44-a2e6-0864dcd0e18a"
   strings:
      $header = "<%@ Page Language=\"C#\" %>"
      $body = "<% HttpPostedFile thisFile = Request.Files[0];thisFile.SaveAs(Path.Combine"
   condition:
      $header at 0 and
      $body and
      filesize < 1KB
}