Securing 7 Layers of Insecurity
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Handling Unwanted Email What Are the Main Sources of Junk Email?
Handling unwanted email Almost entirely based on a presentation by Brian Candler What are the main sources of junk email? · Spam Unsolicited, bulk email Often fraudulent ± penis enlargement, lottery scams, close relatives of African presidents, etc. Low response rate => high volume sent · Viruses, Trojan horses Infected machine sends out mails without the owner 's knowledge · Malicious bounces These are called ªcollateral spamº or ªJoe-jobsº Junk mail is sent with forged MAIL FROM Accepted by some intermediate MTA, but later it bounces Bounces go to innocent third party 1 What are the costs? · Important messages can be accidentally discarded The more junk, the higher the risk · Wasted time Deleting junk Setting up and maintaining ®lters Checking discarded mail for false positives · Wasted bandwidth and disk space Especially for users on modems Viruses and spam attachments can be large · Annoyance, offence, even fraud There are no easy answers! 2 Where can you ®lter? · At the end-user hosts ✓ Each client has full control and customization ✓ Distributes the processing cost ✗ Client must still download each message · On the ISP's mail server ✓ Easier for users ✓ Sometimes can be rejected before receiving the body ✓ Saves disk space on the server ✗ Hard to make ¯exible for users to customize The Joe-job problem · Don't accept a message and then bounce it later If its sender is forged, we are creating a Joe-job · Much better to reject at RCPT TO or DATA stages A real MTA sender will create a bounce Spamware will ignore the rejection · For -
What Is SPF? Introduction
Valimail White Paper February 2018 What is SPF? Introduction Sender Policy Framework (SPF) is a Work on SPF started in 2003, and domains cornerstone of email authentication, and is the have been deploying it increasingly widely first of several standards established for that since then. SPF was published as RFC 4408 purpose. in 2006, and became an officially proposed Internet standard via RFC 7208 in 2014. In a simplistic sense, SPF lets you create a whitelist for IP addresses. If a mail server SPF is widely used by major and minor with an IP address that’s not on your list tries receivers of email (Google, Microsoft, Yahoo, to send email using your domain, it won’t etc.) as well as all Secure Email Gateways pass the SPF authentication test. (SEGs). How It Works The way SPF works is quite simple in principle: For instance, we examined the SPF records for all 62 sponsors of the 2017 1. Domain owners publish SPF records to RSA Conference. We found 58 who had the Domain Name System (DNS) that spell published SPF records, but 17 of those out the rule sets for their domains. An had records with errors in them. That’s SPF record is plain text, and it can be a nearly 30 percent failure rate — and as simple as a single line listing the IP that’s among security companies. addresses that are allowed to send email on the domain’s behalf. Companies that don’t have a lot of expertise in cybersecurity in general (and email 2. When an email server receives an incoming security in particular) often find SPF email, it examines the domain shown in even more tricky. -
Electronic Mail
CSECSE 265:265: SystemSystem andand NetworkNetwork AdministrationAdministration ● Electronic Mail – Mail systems – Addressing, mail headers – Client/server philosophy, mail homes – Aliases, mail routing, mailing list software – sendmail – Security – Performance Spring 2016 CSE 265: System and Network Administration ©2004-2016 Brian D. Davison MailMail systemssystems ● Four components – Mail user agent (MUA) to read and compose mail – Mail transport agent (MTA) route messages – Delivery agent that stores messages for later retrieval by users – Optional access agent to connect user agent to message store Spring 2016 CSE 265: System and Network Administration ©2004-2016 Brian D. Davison TheThe bigbig picturepicture Spring 2016 CSE 265: System and Network Administration ©2004-2016 Brian D. Davison UserUser agentsagents ● Provide means to read and compose email – Outlook, Thunderbird, Eudora, pine, elm, IMP, /bin/mail, emacs, web-based gmail, and more ● Often have system-wide and personal configuration files ● Multipurpose Internet Mail Extensions (MIME) encoding for different text formats and attachments Spring 2016 CSE 265: System and Network Administration ©2004-2016 Brian D. Davison TransportTransport agentsagents ● Transport agents accept mail from a user agent, and deliver mail to the correct hosts – PMDF, postfix, smail, Exim, sendmail ● Speak the Simple Mail Transport Protocol (SMTP) or Extended SMTP (ESMTP) ● Run on port 25 (unencrypted) Spring 2016 CSE 265: System and Network Administration ©2004-2016 Brian D. Davison DeliveryDelivery agentsagents – Accepts mail from a transport agent, and delivers to the local recipient – Delivery can be to ● a person's mailbox ● a mailing list ● a file ● a program – Agents include ● /bin/mail for local users ● /bin/sh for programs ● /usr/bin/procmail for user-configurable delivery Spring 2016 CSE 265: System and Network Administration ©2004-2016 Brian D. -
Presentations Made by Senders
SES ���� ��� � �� � � � � � � � ������������� DomainKeys ��������� SPF ��������������������� ���������� ����������������� ������������������������������������������������ Contents Introduction 3 Deployment: For Email Receivers 6 Audience 3 Two Sides of the Coin 6 How to Read this White Paper 3 Recording Trusted Senders Who Passed Authentication 6 A Vision for Spam-Free Email 4 Whitelisting Incoming Forwarders 6 The Problem of Abuse 4 What To Do About Forgeries 6 The Underlying Concept 4 Deployment: For ISPs and Enterprises 7 Drivers; or, Who’s Buying It 4 Complementary considerations for ISPs 7 Vision Walkthrough 5 Deployment: For MTA vendors 8 About Sender Authentication 8 Which specification? 8 An Example 8 Conformance testing 8 History 8 Perform SRS and prepend headers when forwarding 8 How IP-based Authentication Works 9 Add ESMTP support for Submitter 8 The SPF record 9 Record authentication and policy results in the headers 8 How SPF Classic Works 9 Join the developers mailing list 8 How Sender ID works 9 Deployment: For MUA vendors 9 How Cryptographic Techniques Work 0 Displaying Authentication-Results 9 Using Multiple Approaches Automatic switching to port 587 9 Reputation Systems Deployment: For ESPs 20 Deployment: For Email Senders 2 Don’t look like a phisher! 20 First, prepare. 2 Delegation 20 Audit Your Outbound Mailstreams 2 Publish Appropriately 20 Construct the record 2 Deployment: For Spammers 2 Think briefly about PRA and Mail-From contexts. 3 Two Types of Spammers 2 Test the record, part 3 Publish SPF and sign with DomainKeys. 2 Put the record in DNS 3 Stop forging random domains. 2 Test the record, part 2 4 Buy your own domains. 2 Keep Track of Violations 4 Reuse an expired domain. -
DMARC: Monitor & Secure Your Email Delivery
Guide DMARC: Monitor & secure your email delivery Chris Nagele Founder of Wildbit postmarkapp.com Read the web version. Do you know every source of email for your domain? Are spammers trying to spoof your email domain for hacking or fraud opportunities? Are you complying with the best email practices to ensure inbox delivery? These are the questions that DMARC answers, giving you full control of email delivery for your company’s domain. At Postmark, email authentication has been extremely important to us from day one. We believe that anyone should be able to easily send emails with proper infrastructure, tools, and email standards without having to pay enterprise prices. DMARC, and our support of it, is a big part of this mission. 2 What is DMARC? DMARC (Domain-based Message Authentication, Reporting & Conformance) is a standard that prevents spammers from using your domain to send email without your permission — also known as spoofing. Spammers can forge the “From” address on messages so the spam appears to come from a user in your domain. A good example of this is PayPal spoofing, where a spammer sends an email to you pretending to be PayPal in an effort to obtain your account information. DMARC ensures these emails get blocked before you even see them in your inbox. In addition, DMARC gives you great visibility and reports into who is sending email on behalf of your domain, ensuring only legitimate email is received. The good news is that DMARC is open and free for anyone to use, allowing you to secure your domain’s emails and gain control of your email delivery. -
Set up Mail Server Documentation 1.0
Set Up Mail Server Documentation 1.0 Nosy 2014 01 23 Contents 1 1 1.1......................................................1 1.2......................................................2 2 11 3 13 3.1...................................................... 13 3.2...................................................... 13 3.3...................................................... 13 4 15 5 17 5.1...................................................... 17 5.2...................................................... 17 5.3...................................................... 17 5.4...................................................... 18 6 19 6.1...................................................... 19 6.2...................................................... 28 6.3...................................................... 32 6.4 Webmail................................................. 36 6.5...................................................... 37 6.6...................................................... 38 7 39 7.1...................................................... 39 7.2 SQL.................................................... 41 8 43 8.1...................................................... 43 8.2 strategy.................................................. 43 8.3...................................................... 44 8.4...................................................... 45 8.5...................................................... 45 8.6 Telnet................................................... 46 8.7 Can postfix receive?.......................................... -
Messagelabs Email Security Services Administrator Guide
Email Security Services Administrator Guide For Microsoft Exchange® Environments Licensed Customer Confidential Licensed Customer Confidential Legal Notices Copyright© 1998-2009 Dell MessageOne, Inc. All Rights Reserved. Information in this document is subject to change without notice. All names of companies, organizations, persons, or other entities, and all sample data used in content and examples is fictitious and not meant to represent any real company, organization, person, or actual data. No part of this publication may be reproduced, modified, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise without the prior written permission of Dell MessageOne, Inc. Reproduction prohibitions do not extend to distribution among the employees of licensed customers or for use in activities conducted by Dell MessageOne partners in the course of sales, marketing, training, or support. MessageOne is a registered trademark and “Business Continuity that makes Business Sense,” EMS, SyncManager, RedirectorSink, RedirectorController, RecoveryManager, and OneSwitch are trademarks of Dell MessageOne, Inc. MessageLabs® and the MessageLabs logo are trademarks of MessageLabs Ltd. Research in Motion, RIM, and BlackBerry are trademarks/registered trademarks of Research in Motion Limited. All other trademarks are the property of their respective owners. This product uses certain third-party software. Relevant licensing information is provided in the MESSAGEONE LICENSE file in the installation directory. Dell -
Using Dmarc to Improve Your Email Reputation Zink
USING DMARC TO IMPROVE YOUR EMAIL REPUTATION ZINK USING DMARC TO IMPROVE up with ways to mitigate this problem using two primary technologies. YOUR EMAIL REPUTATION Terry Zink 1.1 Terminology Microsoft, USA In email, people naturally thing that the sender of the message is the one in the From: fi eld – the one that they see in their email Email [email protected] client. For example, suppose that you are a travel enthusiast and you receive the email shown in Figure 3. You received the message ‘from’ [email protected], right? Wrong. ABSTRACT In email, there are two ‘From’ addresses: In 2012, the world of email fi ltering created a new tool to combat 1. The SMTP MAIL FROM, otherwise known as the RFC spam and phishing: DMARC [1, 2]. DMARC, or Domain-based 5321.MailFrom [3]. This is the email address to which the Message Authentication, Reporting & Conformance, is a technology that is designed to prevent spammers from From [email protected] <[email protected]> forging the sender, thus making brands more resistant to Subject Receipt for your Payment to Penguin Magic abuse. However, its most powerful feature is the built-in To Me reporting mechanism that lets brand owners know they are being spoofed. June 10, 2014 08:42:54 PDT DMARC has its upsides, and it is very useful for Transaction ID: 8KAHSL918102341 preventing spoofi ng, but it also has some drawbacks – it will fl ag some legitimate email as spam, and it will Hello Terry Zink, cause some short-term pain. You sent a payment of $427.25 USD to Penguin Magic. -
Permanent Email • Spam and Spoofing
CU eComm Program Permanent Email • Spam and Spoofing We get a lot of inquiries regarding SPAM. As a result, we have compiled a list of the most frequently asked questions with explanations for each. See below. I hope you find this information helpful. SPAM FAQ Is the alumni association sending me spam? No. Neither the alumni association nor Harris Internet Services, who host the Alumni Connections servers that maintain the email forwarding service, are the source of the spam. We respect your privacy and do not sell, or otherwise distribute, alumni email addresses; nor have they been stolen. How did the spammers get my address? Unfortunately, there are many ways that spammers obtain email addresses: addresses compiled by commercial entities from web commerce; web crawlers searching for specific domain names (such as @alumni.anyschool.edu) on any web site where contact information might be listed; and a practice sometimes called "blind spamming" or "dictionary spamming" in which spammers simply guess at the username before the @ sign and send literally thousands of messages. This is why you may see a message addressed to "albert@, allen@, andrew@ ...," etc. The spammers run what is basically a dictionary of usernames against a domain • those that don't immediately bounce are kept and reused. This can give the false impression that the spammer has access to the list of user accounts. Viruses can also generate unwanted email and harvest addresses for spammers. Even if your computer is not infected, if someone else has your address in their address book and their computer becomes infected, viruses will often send multiple messages to everyone in the address book. -
Email Sender Authentication Development and Deployment
EMAIL SENDER AUTHENTICATION DEVELOPMENT AND DEPLOYMENT (PROJECT CHEESEPLATE) Volume I Technical and Management Proposal pobox.com IC Group, Inc. [email protected] v1.01 20041217 Full Proposal Control Number EB8A Email Sender Authentication OFFICIAL TRANSMITTAL LETTER IC Group, Inc., a New York State corporation, doing business as pobox.com, respectfully submits a proposal in response to solicitation BAA04-17 for Cyber Security Research and Development. It is submitted under Category 3, Technical Topic Area 7, Technologies to Defend Against Identity Theft, for consideration as a Type II Prototype Technology. Solicitation Title: BAA 04-17 Topic Title: Technologies to Defend Against Identity Theft Type Title: Type II (Prototype Technologies) Full Proposal Control Number: EB8A Proposal Title: Email Sender Authentication A companion proposal, Reputation System Clearinghouse (1RGT), is also being submitted under the same category and type. We request that these two proposals be read together. This proposal should be read first. This proposal was authored by Meng Weng Wong, Founder and Chief Technology Officer for Special Projects. He can be contacted at [email protected]. Meng Weng Wong IC Group, Inc. 1100 Vine St Ste C8 Philadelphia, PA 19107 December 15th 2004 EIN: 113236046 Central Contractor Registration: 3EKUCT Email Sender Authentication 2 EXECUTIVE SUMMARY Pobox.com aims to fight phishing by adding sender authentication “Phishing” is a class of high-tech scam that functionality to the Internet email system. First we will build a library uses fraudulent e-mail to deceive consum- ers into visiting fake replicas of familiar to implement a useful set of recently devised anti-forgery specifica- Web sites and disclosing their credit card tions, including ip-based approaches such as SPF and crypto-based numbers, bank account information, Social approaches such as DomainKeys. -
Abkürzungs-Liste ABKLEX
Abkürzungs-Liste ABKLEX (Informatik, Telekommunikation) W. Alex 1. Juli 2021 Karlsruhe Copyright W. Alex, Karlsruhe, 1994 – 2018. Die Liste darf unentgeltlich benutzt und weitergegeben werden. The list may be used or copied free of any charge. Original Point of Distribution: http://www.abklex.de/abklex/ An authorized Czechian version is published on: http://www.sochorek.cz/archiv/slovniky/abklex.htm Author’s Email address: [email protected] 2 Kapitel 1 Abkürzungen Gehen wir von 30 Zeichen aus, aus denen Abkürzungen gebildet werden, und nehmen wir eine größte Länge von 5 Zeichen an, so lassen sich 25.137.930 verschiedene Abkür- zungen bilden (Kombinationen mit Wiederholung und Berücksichtigung der Reihenfol- ge). Es folgt eine Auswahl von rund 16000 Abkürzungen aus den Bereichen Informatik und Telekommunikation. Die Abkürzungen werden hier durchgehend groß geschrieben, Akzente, Bindestriche und dergleichen wurden weggelassen. Einige Abkürzungen sind geschützte Namen; diese sind nicht gekennzeichnet. Die Liste beschreibt nur den Ge- brauch, sie legt nicht eine Definition fest. 100GE 100 GBit/s Ethernet 16CIF 16 times Common Intermediate Format (Picture Format) 16QAM 16-state Quadrature Amplitude Modulation 1GFC 1 Gigabaud Fiber Channel (2, 4, 8, 10, 20GFC) 1GL 1st Generation Language (Maschinencode) 1TBS One True Brace Style (C) 1TR6 (ISDN-Protokoll D-Kanal, national) 247 24/7: 24 hours per day, 7 days per week 2D 2-dimensional 2FA Zwei-Faktor-Authentifizierung 2GL 2nd Generation Language (Assembler) 2L8 Too Late (Slang) 2MS Strukturierte -
Canit-PRO User's Guide
CanIt-PRO User’s Guide for Version 10.2.5 AppRiver, LLC 13 September 2018 2 CanIt-PRO — AppRiver, LLC Contents 1 Introduction 13 1.1 Organization of this Manual.............................. 13 1.2 Definitions........................................ 14 2 The Simplified Interface 19 3 The My Filter Page 21 3.1 Sender Rules...................................... 21 3.2 The Quarantine..................................... 22 3.3 Online Documentation................................. 22 4 The CanIt-PRO Quarantine 23 4.1 Viewing the Quarantine................................. 23 4.1.1 Message Summary Display........................... 23 4.1.2 Sort Order.................................... 24 4.1.3 Message Body Display............................. 25 4.1.4 Summary of Links............................... 25 4.2 Message Disposition.................................. 25 4.2.1 Quick Spam Disposal.............................. 26 4.3 Reporting Phishing URLs................................ 27 4.4 Viewing Incident Details................................ 27 4.4.1 Basic Details.................................. 28 4.4.2 Address Information.............................. 29 4.4.3 History..................................... 29 4.4.4 Spam Analysis Report............................. 29 4.5 Viewing Other Messages................................ 30 4.6 Viewing Specific Incidents............................... 30 CanIt-PRO — AppRiver, LLC 3 4 CONTENTS 4.7 Searching the Quarantine................................ 30 4.8 Closed Incidents....................................