The goal of email spoofing is to trick the user into thinking an email is from a known and trusted source. Spoofing is done through the manipulation of email elements that are visible to the recipient, primarily the “Body From” field.
A spoofed email can be partial or full:
Partial Spoof: A partial spoof occurs when only the “Body From” is masked, with the Envelope Sender being set to something else. This spoof type can be managed with Domain-based Message Authentication, Reporting & Conformance (DMARC), which is an email authentication, policy, and reporting protocol.
Full Spoof: A full spoof occurs when both the “Body From” and Envelope Sender are spoofed. This spoof type can be managed with Sender Policy Framework (SPF). SPF is an email-validation system designed to detect email spoofing by providing a mechanism to allow mail exchangers to check that incoming mail comes from an authorized host.
However, there are certain technical circumstances where the use of either SPF or DMARC is not possible. This may be due to the number of valid sources extending beyond the capacity of SPF, a technical constraint, or your own DMARC infrastructure. This leaves you exposed to spoofing.
Table: Unknown, untrusted spoof examples
Bad Partial Spoof (unknown or malicious source):
Bad Full Spoof (unknown or malicious source):
X-Originating-IP: [184.108.40.206] X-Env-Sender: email@example.com From: <firstname.lastname@example.org> To: <email@example.com>
X-Originating-IP: [220.127.116.11] X-Env-Sender: firstname.lastname@example.org From: <email@example.com> To: <firstname.lastname@example.org>
In both spoof examples, the IP addresses are unknown sources, which are not allowed to spoof you). The Body From is masked to look like your domain; the Envelope Sender may or may not be masked to match your domain.
Table: Known, trusted spoof examples
Good Partial Spoof (valid or approved source):
Good Full Spoof (valid or approved source):
X-Originating-IP: [18.104.22.168] X-Env-Sender: email@example.com From: <firstname.lastname@example.org> To: <email@example.com>
X-Originating-IP: [22.214.171.124] X-Env-Sender: firstname.lastname@example.org From: <email@example.com> To: <firstname.lastname@example.org>
Spoofed email does not necessarily mean that the email you receive is spam or bad; it can be legitimate and important to you. Today’s businesses rely heavily on legitimate spoofing for their business to function. Common email marketing services like MailChimp, Amazon SES, and Zoho Campaigns are typical mail service providers for sending newsletters.
Table: Ghost spoof examples
Bad Ghost Spoof (unknown or malicious source):
Good Ghost Spoof (valid or approved source):
X-Originating-IP: [126.96.36.199] X-Env-Sender: email@example.com From: “firstname.lastname@example.org” <email@example.com> To: <firstname.lastname@example.org>
X-Originating-IP: [188.8.131.52] X-Env-Sender: email@example.com From: “firstname.lastname@example.org” <email@example.com> To: <firstname.lastname@example.org>
A third type of spoof—which we refer to as a ghost spoof— is not technically spoofing, but it does exploit an element of the Body From. This element is the Display Name field.
A ghost spoof deals with an open text field that is not controlled in any way. Your email client will only show the display when one exists, especially if the display name matches the internal naming scheme. Your users would see the text inside the ” “, but not the Body From email. This varies between email clients.
Email headers contain important information about the origin and path an email took before arriving at its final destination, including the sender’s IP address, internet service provider, email client, and even location. The information could be used to block future emails from the sender (in the case of spam) or to determine the legitimacy of a suspicious email. A review of the headers can also help to identify “header spoofing,” a strong indication the email was sent with malicious intent.
Understanding the Header Fields
Email headers are read chronologically from the bottom up and can be broken down into three main categories: 1) Message Information 2) X-Headers and 3) Server Relay Information. There is a convenient tool for analyzing headers available online at http://mxtoolbox.com/EmailHeaders.aspx. Simply copy and paste the headers into the tool, and it will analyze the server relays and convert the headers into an easy to read format.
Message Information: Includes commonly recognized email header fields, such as To:, From:, Subject:, Date:, To:, as well as useful fields like Message-ID:, Return-Path:, ReplyTo:, among others. These fields are the most easily spoofed because they are specified by the sender’s mail client. They are usually found near the bottom of the headers as they are the first to be added.
Figure 1: Headers – Message Info
X-Headers: These fields are added to the email by security devices such as email anti-virus scanners as it traverses the internet and internal networks. The X-Headers may not be in order and are often intermixed within the Message Info and Server Relay headers. Not all X-Headers will be present in every case. In the example below there is an X-Originating-Email: that reveals the true sender was email@example.com and not firstname.lastname@example.org. Sometimes there is an X-Originating-IP as well. The headers below also show that the email was scanned by Agari Email Security and IronPort devices.
Figure 2: Headers – X-Headers
Server Relay Information: Each time a server relay receives an SMTP message, it will add a new Received: line at the beginning of the header block. A typical email received by a user on a corporate network will show many server relays both before and after being delivered to the corporate email servers (companyserver.com). These will be in chronological order starting from the bottom up.
Figure 3: Headers: Server Relay
By analyzing the server relay information in chronological order from the bottom-up, you can get a picture of where the message travelled. Each receiving mail server adds the name and IP address of the server that delivered the message. The server name may reveal the domain of the sender relay, and a Who-Is lookup of the IP may give you a geographic location. In the case of messages sent via Gmail and other large email service providers, this may only lead you back to the location of the email servers or even the corporate headquarters of the provider (i.e. Mountain View, CA). If you are lucky, the headers will include an X-Originating-IP that may reveal the sender’s internet service provider and narrow down the sender’s location.
If you are looking at spam email headers from a network security perspective, it is important to identify the IP address/domain that delivered the email to your frontline email server, the security device in front of your email server. This is called the “originating IP” (not the same as X-Originating-IP). It is the first field added to the headers that can be 100% trusted because it was added by your own security device/server. The server relay header will read “Received: from some.external.domain ([some.IP]) by your.company.device ([your.IP]).” Potentially, everything before this entry could be spoofed, but, as your server is reporting it received an email from some.external.domain ([some.IP]) and is the one adding it to the headers, you should be able to trust it. Once you know which external IP delivered the message, there is a free reputation service provided by Cisco at https://www.senderbase.org/. The service gives IP addresses and domains a reputation rating (Known spammer IP’s and domains received “Poor” reputations). The originating IPs can be blocked at the externally facing firewalls on a case by case basis, by reputation, or both. Figure 4 shows an email received by msg2.companyserver.com and the originating IP/domain is highlighted. Figure 5 shows the “Poor” rating the IP received from SenderBase.org.
Figure 4: Headers – Originating IP
Figure 5: SenderBase.org – Reputation Rating
It is important to look for evidence of spoofing or alteration of header data in the Message Information headers. The spammer can easily alter these headers within their email client or by using specialized software. The most common field to spoof is the From: field. In the example in Figure 2, the sender changed the From: field to display “Mike McDuck <email@example.com>” but the true sender was revealed by the X-Originating-Email field. It is not uncommon for spammers to use the recipient’s own name and email address in the From: field in order to increase the chances the recipient will open the email (“Why did I send this email to myself?”). The spammer will use any trick he or she can think of to deceive the recipient. Keep in mind the Return-Path: and Reply-To: can also be spoofed, depending on whether the spammer wants to receive the reply messages or not. Sometimes the To: field will also be altered to hide the intended recipient’s address.
The Message-ID is another good place to identify spoofing. The Message-ID is a unique identifier of digital messages and is difficult to alter as it is added by the mail server that processes the email. Because it has to be unique, it is common for message systems to use a date/time stamp followed by the sender’s domain name (example: CAF4Ths+hsd84G9sedaD@mail.gmail.com). If the sender domain in the From: field does not match the Message-ID, you might be dealing with a spoofed message.
The majority of spam emails are generated by servers capable of producing millions of messages per day. Sometimes those servers are running programs that populate the “X-Mailer” field with the name of the mail client that was used. Legitimate emails will usually include a known mail client (i.e. Microsoft Outlook 16.0, Outlook Express, iPad Mail), but the spammer mail clients may be something less common (see Figure 6) or even obscured through random, nonsense characters.
Figure 6: Headers – Mail Client
At first glance, email headers can seem confusing and overwhelming. Once you begin to understand the fields in the headers and what they can reveal about the message, you will find very useful information buried in the seemingly endless lines of text. The next step will be determining what you can do with the evidence you find. Stay tuned to for future blog posts on using the headers to identify/block spam and to detect targeted phishing emails.
When sending from a Mobile device via the ActiveSync service the device fails to send.
Some devices may return an error indicating that “The message that was sent to the server was rejected because the message was too large”. (Apple iPad iOS). Not all mobile devices behave this way and may just keep the message in the outbox folder and retried until removed from the folder.
Ther are number of reasons, couple of them listed below.
First one I have found is ActiveSync limit set to 10MB (%ExchangeInstallPath%ClientAccess\Sync\web.config maxRequestLength=”10240″)
A global IIS restriction preventing uploads larger than 49152 Bytes.
IIS 7.5 sets a default value of 49152 Bytes for the “UploadReadAheadSize” value which limits the amount of bytes allowed in the entity body of a request and the number of bytes a Web server will read into a buffer and pass to an ISAPI extension.
Navigate within IIS to the “Sites” node.
Determine the ID for the “MailEnable Protocols” website
Next navigate to the IIS log files path: C:\inetpub\logs\LogFiles
Locate the W3SVC(ID) folder, where ID is the number of the website ID above in step 2.
Sort the log files by “Date Modified’ and then open the latest log files in respect to the date/time you sent the message from the mobile device.
maxAllowedContentLength="30000000 bytes" Not present by default (see comments).
<add key="MaxDocumentDataSize" value="10240000">
Comments on ActiveSync limits
By default, there is no maxAllowedContentLength key in the web.config files for ActiveSync. However, the maximum message size for ActiveSync is affected by the maxAllowedContentLength value that is applied to all web sites on the server. The default value is 30000000 bytes (30 MB). To see these values for ActiveSync on Client Access Servers and Mailbox servers in IIS Manager, perform the following steps:
Do one of the following steps:
On Client Access servers, open IIS Manager, navigate to Sites > Default Web Site and select Microsoft-Server-ActiveSync.
On Mailbox servers, open IIS Manager, navigate to Sites > Exchange Back End and select Microsoft-Server-ActiveSync.
Verify Features View is selected, and double-click Configuration Editor in the Management section.
Click the dropdown arrow in the Section field, navigate to system.webServer > security and select requestFiltering.
In the results, expand requestLimits, and you’ll see maxAllowedContentLength and the default value 30000000 (bytes).
To change the maxAllowedContentLength value, enter a new value in bytes, and click Apply. You need to change the value on Client Access servers and on Mailbox servers. After you change the value in IIS Manager, a new maxAllowedContentLength key is written to the corresponding web.config file (%ExchangeInstallPath%FrontEnd\HttpProxy\Sync\web.config on Client Access servers, and %ExchangeInstallPath%ClientAccess\Sync\web.config on Mailbox servers).
To change the maximum message size for ActiveSync clients, you need to change the value of maxRequestLength in the web.config file on Client Access servers and Mailbox servers, MaxDocumentDataSize in the web.config file on Mailbox servers, and maxAllowedContentLength in IIS Manager on Client Access servers and Mailbox servers.
RESOLUTION – 2
Open a Windows command prompt with administrator rights and navigate to the following location: C:\inetpub\AdminScripts
Run the following command: cscript adsutil.vbs set w3svc/14/uploadreadaheadsize 51200000
Where “14” in the above command is the website ID
RESOLUTION – 3
Check the virtual directory authentication settings in the Exchange server for EWS (Default Web Site), it should be Integrated windows authentication only and for
Microsoft-Server-ActiveSync (Default Web Site) authentication set to Basic authentication and ignore client certificate
If you are an Exchange administrator, then using the Set-MailboxAutoReplyConfiguration Exchange PowerShell command is the supported and native way to go to enable Automatic Replies without logging on to the mailbox itself.
So onto the printer side. Open the webpage to configure the device (Enhanced web Service, shortened from here on as EWS)
EWS > Connectivity > SMTP
Which will show you this (normally I would pre-fill this with your settings, but since I don’t know your settings because of your SMTP server not showing them on its website, I’m using GMAIL as my example.
1. Device Email and SMTP AUTH user name have to match
2. The 2 password boxes are pretty self-evident.
3. Validation Type absolutley needs to be set to On Device
4. SMTP server address is whatever Media Temple says to use from the link above, the port number too, and the Connection Security (maybe called Encryption) too.
Of course the SMTP server name can be the IP address or the hostname of the server, but to use the hostname, you have to make sure DNS is correct on the printer EWS > Connectivity > Ethernet > DNS > Edit
And if HTTPS is enabled on the printer, or SSL/TLS/STARTTLS is being used for Encryption, then the time must be correct to within 3 minutes EWS > System > Date& Time
If you set it up correctly and get odd faults (017-714 for instance, try updating the firmware, the launch firmware has issues with SHA-2), you can get the latest firmware right here
Open up SSMS RUN AS ADMINISTRATOR and connect here:\\.\pipe\MICROSOFT##WID\tsql\query
Open a query window, run this query:
SELECT TOP 1000 [Id],[Name] FROM [RDCms].[rds].[Server]
Look at the list of servers in the NAME column. Find your dead server and note the ID number in the ID column. For this example, lets say my id is “5”. The ID for your system will most likely be different so don’t just copy and paste the below commands, make sure you change the ID to what you actually need to remove.
—-MAKE SURE YOU HAVE A DATABASE BACKUP OR SYSTEM CHECKPOINT OR SYSTEM BACKUP OR SOMETHING BEFORE PROCEEDING—-
Run the following query to remove the dead SESSION HOST server from the database:
use RDCms; delete from rds.RoleRdsh where ServerID = ‘5’;
I also needed to remove the server from the rds.Server table:
use RDCms; delete from rds.Server where Id = ‘5’;
Note, the above covers the session host role. If you have a server with other roles there are other tables you can look at and delete by id. Just right-click on the table (after drilling down in object explorer in to the RDCms database) and “Select Top 1000 rows” to see if your server ID is listed there.