paste := "xhUTm9C4"
password := "qwerty"
baseUrl := "https://pastebin.com/"

WR := new WebRequest
html := WR.Fetch(baseUrl . paste)
if WR.error
   throw WR.error
RegExMatch(html, "name=""_csrf-frontend"" value=""\K[^""]+", _csrf_frontend)
if !_csrf_frontend
   throw "_csrf-frontend code not found"

body := "_csrf-frontend=" . EncodeDecodeURI(_csrf_frontend)
      . "&is_burn=1"
      . "&PostPasswordVerificationForm%5Bpassword%5D=" . EncodeDecodeURI(password)
      
Headers := { "content-length": StrLen(body)
           , "content-type"  : "application/x-www-form-urlencoded"
           , "pragma"        : "no-cache"
           , "cache-control" : "no-cache"
           , "user-agent"    : "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 "
                             . "(KHTML, like Gecko) Chrome/104.0.5112.81 Safari/537.36 Edg/104.0.1293.54" }

html := WR.Fetch(baseUrl . paste, "POST", Headers, body)
if WR.error
   throw WR.error
WR := ""

Doc := ComObjCreate("htmlfile")
Doc.write("<meta http-equiv=""X-UA-Compatible"" content=""IE=9"">")
Doc.write(html)

textArea := Doc.querySelector("textarea.js-paste-raw")
if !IsObject(textArea)
   throw "textarea not found"
code := textArea.value
Doc := ""

MsgBox, % code

class WebRequest
{
   __New() {
      this.whr := ComObjCreate("WinHttp.WinHttpRequest.5.1")
   }
   
   __Delete() {
      this.whr := ""
   }
   
   Fetch(url, method := "GET", HeadersArray := "", body := "", ByRef outData := "") {
      this.whr.Open(method, url, true)
      for name, value in HeadersArray
         this.whr.SetRequestHeader(name, value)
      this.error := ""
      this.whr.Send(body)
      this.whr.WaitForResponse()
      status := this.whr.status
      if (status != 200)
         this.error := "HttpRequest error, status: " . status
      Arr := this.whr.responseBody
      pData := NumGet(ComObjValue(arr) + 8 + A_PtrSize)
      length := Arr.MaxIndex() + 1
      if !IsByref(outData)
         res := StrGet(pData, length, "UTF-8")
      else {
         VarSetCapacity(outData, length, 0)
         DllCall("RtlMoveMemory", "Ptr", &outData, "Ptr", pData, "Ptr", length)
         res := length
      }
      Return res
   }
}

EncodeDecodeURI(str, encode := true, component := true) {
   static Doc, JS
   if !Doc {
      Doc := ComObjCreate("htmlfile")
      Doc.write("<meta http-equiv=""X-UA-Compatible"" content=""IE=9"">")
      JS := Doc.parentWindow
      ( Doc.documentMode < 9 && JS.execScript() )
   }
   Return JS[ (encode ? "en" : "de") . "codeURI" . (component ? "Component" : "") ](str)
}