Franzes Francisco Manila IBM Domino Server Crash and Messaging

Transcription

1 Franzes Francisco Manila IBM Domino Server Crash and Messaging

2 Topics to be discussed What is SPAM / Spoofing? How to identify one? Anti-SPAM / Anti- spoofing basic techniques Domino configurations to prevent spam / spoofing Common questions on how Domino controls SPAM / spoofing

3 What are spam / spoofing? Junk , unsolicited bulk s from unknown sources. Spam is basically anything that you did not request to receive via . (Signing up for a newsletter and allowing the vendor to share your address is NOT spam! )

4 Where do they come from? Bots, virus-infected computers, remotely controlled systems, malicious applications / attachments that send about 85% of spam. Spammers/Hackers that collect addresses from forums, websites, customer lists, newsgroups, and viruses which harvest users' address books (Mostly from Windows systems. NSFs are ACL/ID protected), and are shared and sold to other spammers.

5 Types of Spam / Spoofed s Spam advertising sites Websites or mass s sent to users with odd or too good to be true offers. Some are also ads that are collected by cookies of websites you visit. Common products / issues Scams Spam s that are sent to advertise common products that you are not aware or you didn t purchase or subscribe. Spam s that ask for payments either for your credit card bill or state that you have a relative that is in need or in trouble. Phishing A spam method that aims to collect info or credentials from users and usually mask as legitimate s. Spoofed headers A spam method where an unsuspicious contains a r er service or infected in the body / page source of the mail. Backscatter Spam method where spammers send undeliverable mails intentionally to a mail server to inflict mail traffic Other examples Images that contain no text, but has infected contents on the page source that is very hard for scanners to check. Content has a link (often leading to really bad stuff), the rest of message is random ramblings that do not make sense. Sometimes hidden. Messages that appear to come from friends that ask you to follow a link, or open an attachment. Beware!

6 Top countries that are mostly infected by SPAM WORLD'S WORST SPAM HAVEN COUNTRIES FOR ENABLING SPAM (2017) Source:

7 How does SPAM / SPOOFED s affect your environment? Can cause major traffic and server performance issues. Worse, legitimate s can be damaged. Can degrade your internet domain s credibility. (getting blacklisted) Can exploit and open a gateway to your internal network. Can affect user s personal files and contents. One of the worst case identified recently that can be caused by SPAM / Spoofed mails are RANSOMWARE attacks.

8 Verifying a SPAM / SPOOFED Anatomy of a Spam / Spoofed Notice the unique HTTP string? This string is used to confirm that you read the message, but only if you load the images.

9 Verifying a SPAM / SPOOFED Looking at the page source: Received: from lpms.beantowntech.com ([ ]) by newfrontier.beantowntech.com with ESMTP id ; Wed, 23 Mar :39: Received: from localhost by lpms.beantowntech.com with LPMS BeanTownTech ESMTP for <john@beantowntech.com> from <SafeTubs@appleeleganto.top>; Wed, 23 Mar :39: Received: from 00b7be99.appleeleganto.top ( ) by lpms.beantowntech.com ( ) with LPMS BeanTownTech ESMTP; Wed, 23 Mar :07: Received: from 00b7be99.9x91f.appleeleganto.top (amavisd, port 8813) by 9x91f.appleeleganto.top with ESMTP id 00VFOHJLDFB7BEJNNROOHJ99; for <john@beantowntech.com>; Wed, 23 Mar :07: Date: Wed, 23 Mar :07: To: <john@beantowntech.com> From: "Safe Tubs" <SafeTubs@appleeleganto.top> Subject: [SPAM] The Best Walk In Tubs, Browse Ads For Them Here MIME-Version: 1.0 X-ISS-IPR: 1001:218 1:57 ( )

10 Verifying a SPAM / SPOOFED Cross Checking the internet domain and IP of the unknown sender Useful Links: html

11 Anti-SPAM / Anti- spoofing basic techniques User education and awareness. Up to date security patches for your Operating System and Domino environment. Enabling network / firewall for spam prevention capabilities NOTE: The best recommended choice to prevent spam / spoofed is by setting up a third party anti-spam application in front of or on the Domino server. Domino was not designed to be a spam appliance. It has capabilities that can prevent light spam attacks but does not have the full functional feature of a Spam Appliance. Using of Spam Filter Gateway or Servers, like IBM s Lotus Protector For Mail Security or others from 3 rd party vendors. Utilizing Domino s configuration.

12 Locking down your Domino environment to prevent SPAM / SPOOF attacks The following settings are not applicable should your Domino server be the second hop into your Domain. Domino should ONLY have these setting set in gateway mode; where Domino is listening directly from the internet. Domino can be configured to prevent some spam s as follows: Locking down Domino as a Relay Server Enable Blacklisting Enable RDNS, and verification of senders Domain in DNS Enable recipient verification on your Domino address book Creating a server mail rule Using FullName Lookup for recipients on your address book

13 Locking down Domino as a Relay Server By default, Domino allows SMTP servers on the same subnet to relay thru the server. To change this and only allow specific systems of ranges, Set the following fields in the Configuration Document - -> Router/SMTP tab --> Restrictions and Controls --> SMTP inbound controls to:

14 Enable Blacklisting You can choose from a number of publicly available and/or private paid subscription services that maintain DNS black lists where Domino can check external connecting hosts. Please refer to the URL below for a list of DNS Black lists. You can enter the text of the error message returned when denying a connection when the connecting host is black listed ( the default error message indicates that the connection was denied for policy reasons) You can use the format specifier %s to specify the IP address of the denied host and a second %s will display the DNS blacklist site where Domino found the host listed. For example: Your IP %s has been Black Listed. For more information contact %s Your IP has been Black Listed. For more information contact examplednsbl.net

15 Enable Blacklisting

16 Verify connecting hostname in DNS You can also enable Domino to check the connecting host name / IP if they have a valid DNS record by setting Configuration Document --> Router/SMTP tab --> Restrictions and Controls --> SMTP inbound controls > Inbound Connection Controls 1. Enabled - Domino verifies the name of the connecting host by performing a reverse DNS lookup. If Domino cannot determine the name of the remote host, it does not allow the host to transfer mail NOTE: Internet SMTP hosts are not required to have PTR entries in DNS. As a result, when this field is enabled, the SMTP task may reject connections from valid SMTP hosts. 2. Disabled - (default) Domino does not check DNS to verify the name of the connecting host.

17 Verify that local domain recipients exist in the Domino Directory Specifies whether the SMTP listener checks recipient names specified in RCPT TO commands against entries in the Domino Directory Choose one: 1. Enabled - If the domain part an address specified in an SMTP RCPT TO command matches one of the configured local Internet domains, the SMTP listener checks all configured directories to determine whether the specified recipient is a valid user but if no matching user name is found, the SMTP server returns a 550 permanent failure response indicating that the user is unknown, for example, 550 bad_user@yourdomain.com... No such user. NOTE: When this setting is enabled and there is an entry in the "Local Internet domain smart host" field, messages that cannot be resolved are not accepted. Therefore, they are not forwarded to the smart host. 2. Disabled - (default) The SMTP listener does not check whether local domain recipients specified in the RCPT TO command are listed in the Domino Directory.

18 Setting Full Name Only It is also advisable to set Fullname only in the configuration document s address lookup field. This will avoid accepting messages for part of a user name, like Joe, or Smith. Setting the field to Fullname only also shuts of the use of soundex which will send a message to a person that has a similar sounding name(soundex value from $Users view).

19 Setting a Server Rule Configuration Document --> Router/SMTP tab --> Restrictions and Controls --> Rules Note that using server mail rules may slow down mail routing depending on the rule created. The more rules that are in place, the more of an impact this will have on routing performance. A server rule could be beneficial for preventing Zero day viruses. This is considering its file type or uniqueness(subject line, sender, body of message) that is identified that can be blocked. Please keep in mind using the " set rule " command at the server console to register the system rule. Also, when disabling a rule, to prevent a ghost rule. Disable the rule first, issue the set rule command, and then you may safely delete the rule.

20 Setting a Server Rule

21 Common questions on how Domino controls SPAM / SPOOFED s Can Domino scan the content of images? documents? attachments? Answer: Domino cannot scan what is in the documents or attachments,but can prevent incoming mail w/ the use of file extensions. Can Domino do settings like quarantine? Answer: If you are aware of certain types of mails that you need to inspect first, Domino can utilize its server mail rule to move messages in a designated location or database for the admin s review. Can we mask our IP or addresses that are already known or exploited by attackers? Answer: Domino can add up or alter it s SMTP banner when doing handshakes to the internet to make it more secure, but as long as an attacker already knows your internal network or internal IP, the changes should be done on the Network level. For an IBM solution to SPAM and Antivirus please see:

22 References:

23 Franzes Francisco Manila IBM Domino Server Crash and Messaging

24 Questions?