Difference between pages "Cell phones" and "Email Headers"

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The following links provide information regarding various technologies and operating systems. Again, feel free to contribute and/or edit.
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'''Email Headers''' are lines of [[metadata]] attached to each [[email]] that contain lots of useful information for a [[forensic investigator]]. However, email headers can be easily forged, so they should never be used as the only source of information.
  
== Quick Links ==
+
== Making Sense of Headers ==
+
[[CDMA]]
+
  
[[GSM]]
+
There is no single way to make sense of email headers. Some examiners favor reading from the bottom up, some favor reading from the top down. Because information in the headers can be put there by the user's [[Mail User Agent|MUA]], a server in transit, or the recipient's [[Mail User Agent|MUA]], it can be difficult to determine when a line was added.
  
[[iDEN]]
+
=== Mail User Agents ===
 +
{{main|List of MUA Header Formats}}
 +
Every [[Mail User Agent|MUA]] sets up the headers for a message slightly differently. Although some headers are required under the applicable [http://www.faqs.org/rfcs/rfc2822.html RFC], their format and ordering can vary by client. Almost all clients, however, add their headers in a fixed format and order.
 +
The examiner can use the format and order for each client to show that messages were forged, but not that they were legitimate. For example, if a message purports to be from [[Apple Mail]] but the order or the headers do not match the [[Apple Mail Header Format]], the message has been forged. If the headers of the message do match that format, however, it does not guarantee that the message was sent by that program.
  
[[GPRS]]
+
=== Servers in Transit ===
  
[[SIM Cards]]
+
Mail servers can add lines onto email headers, usually in the form of "Received" lines, like this:
 +
<pre>Received: by servername.recipeienthost.com (Postfix, from userid 506)
 +
id 77C30808A; Sat, 24 Feb 2007 20:43:56 -0500 (EST)</pre>
  
[[RIM Blackberry]]
+
== Message Id Field ==
  
[[Microsoft PocketPC]]
+
According to the current guidelines for email [http://www.faqs.org/rfcs/rfc2822.html RFC 2822]), every email should have a Message-ID field:
 +
<pre>  The "Message-ID:" field provides a unique message identifier that
 +
  refers to a particular version of a particular message.  The
 +
  uniqueness of the message identifier is guaranteed by the host that
 +
  generates it (see below).  This message identifier is intended to be
 +
  machine readable and not necessarily meaningful to humans.  A message
 +
  identifier pertains to exactly one instantiation of a particular
 +
  message; subsequent revisions to the message each receive new message
 +
  identifiers.
  
[[Microsoft Windows Mobile]]
+
  ...
  
[[Palm]]
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  The message identifier (msg-id) itself MUST be a globally unique
 +
  identifier for a message.  The generator of the message identifier
 +
  MUST guarantee that the msg-id is unique.  There are several
 +
  algorithms that can be used to accomplish this.  Since the msg-id has
 +
  a similar syntax to angle-addr (identical except that comments and
 +
  folding white space are not allowed), a good method is to put the
 +
  domain name (or a domain literal IP address) of the host on which the
 +
  message identifier was created on the right hand side of the "@", and
 +
  put a combination of the current absolute date and time along with
 +
  some other currently unique (perhaps sequential) identifier available
 +
  on the system (for example, a process id number) on the left hand
 +
  side.  Using a date on the left hand side and a domain name or domain
 +
  literal on the right hand side makes it possible to guarantee
 +
  uniqueness since no two hosts use the same domain name or IP address
 +
  at the same time.  Though other algorithms will work, it is
 +
  RECOMMENDED that the right hand side contain some domain identifier
 +
  (either of the host itself or otherwise) such that the generator of
 +
  the message identifier can guarantee the uniqueness of the left hand
 +
  side within the scope of that domain.</pre>
  
[[Symbian]]
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Where known, the Message-ID algorithms for known programs are [[List of MUA Header Formats|given on the separate pages for those programs]].
  
[[Linux]]
+
== Sample Header ==
 +
 
 +
This is an (incomplete) excerpt from an email header:
 +
 
 +
Received: from lists.securityfocus.com (lists.securityfocus.com [205.206.231.19])
 +
        by outgoing2.securityfocus.com (Postfix) with QMQP
 +
        id 7E9971460C9; Mon,  9 Jan 2006 08:01:36 -0700 (MST)
 +
Mailing-List: contact forensics-help@securityfocus.com; run by ezmlm
 +
Precedence: bulk
 +
List-Id: <forensics.list-id.securityfocus.com>
 +
List-Post: <mailto:forensics@securityfocus.com>
 +
List-Help: <mailto:forensics-help@securityfocus.com>
 +
List-Unsubscribe: <mailto:forensics-unsubscribe@securityfocus.com>
 +
List-Subscribe: <mailto:forensics-subscribe@securityfocus.com>
 +
Delivered-To: mailing list forensics@securityfocus.com
 +
Delivered-To: moderator for forensics@securityfocus.com
 +
Received: (qmail 20564 invoked from network); 5 Jan 2006 16:11:57 -0000
 +
From: YJesus <yjesus@security-projects.com>
 +
To: forensics@securityfocus.com
 +
Subject: New Tool : Unhide
 +
User-Agent: KMail/1.9
 +
MIME-Version: 1.0
 +
Content-Disposition: inline
 +
Date: Thu, 5 Jan 2006 16:41:30 +0100
 +
Content-Type: text/plain;
 +
  charset="iso-8859-1"
 +
Content-Transfer-Encoding: quoted-printable
 +
Message-Id: <200601051641.31830.yjesus@security-projects.com>
 +
X-HE-Spam-Level: /
 +
X-HE-Spam-Score: 0.0
 +
X-HE-Virus-Scanned: yes
 +
Status: RO
 +
Content-Length: 586
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Lines: 26
 +
 
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== External Links ==
 +
 
 +
* http://en.wikipedia.org/wiki/Computer_forensics#E-mail_Headers
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* http://www.forensictracer.com software for forensic analysis of internet resources

Revision as of 08:48, 19 March 2007

Email Headers are lines of metadata attached to each email that contain lots of useful information for a forensic investigator. However, email headers can be easily forged, so they should never be used as the only source of information.

Making Sense of Headers

There is no single way to make sense of email headers. Some examiners favor reading from the bottom up, some favor reading from the top down. Because information in the headers can be put there by the user's MUA, a server in transit, or the recipient's MUA, it can be difficult to determine when a line was added.

Mail User Agents

Every MUA sets up the headers for a message slightly differently. Although some headers are required under the applicable RFC, their format and ordering can vary by client. Almost all clients, however, add their headers in a fixed format and order. The examiner can use the format and order for each client to show that messages were forged, but not that they were legitimate. For example, if a message purports to be from Apple Mail but the order or the headers do not match the Apple Mail Header Format, the message has been forged. If the headers of the message do match that format, however, it does not guarantee that the message was sent by that program.

Servers in Transit

Mail servers can add lines onto email headers, usually in the form of "Received" lines, like this:

Received: by servername.recipeienthost.com (Postfix, from userid 506)
	id 77C30808A; Sat, 24 Feb 2007 20:43:56 -0500 (EST)

Message Id Field

According to the current guidelines for email RFC 2822), every email should have a Message-ID field:

   The "Message-ID:" field provides a unique message identifier that
   refers to a particular version of a particular message.  The
   uniqueness of the message identifier is guaranteed by the host that
   generates it (see below).  This message identifier is intended to be
   machine readable and not necessarily meaningful to humans.  A message
   identifier pertains to exactly one instantiation of a particular
   message; subsequent revisions to the message each receive new message
   identifiers.

   ...

   The message identifier (msg-id) itself MUST be a globally unique
   identifier for a message.  The generator of the message identifier
   MUST guarantee that the msg-id is unique.  There are several
   algorithms that can be used to accomplish this.  Since the msg-id has
   a similar syntax to angle-addr (identical except that comments and
   folding white space are not allowed), a good method is to put the
   domain name (or a domain literal IP address) of the host on which the
   message identifier was created on the right hand side of the "@", and
   put a combination of the current absolute date and time along with
   some other currently unique (perhaps sequential) identifier available
   on the system (for example, a process id number) on the left hand
   side.  Using a date on the left hand side and a domain name or domain
   literal on the right hand side makes it possible to guarantee
   uniqueness since no two hosts use the same domain name or IP address
   at the same time.  Though other algorithms will work, it is
   RECOMMENDED that the right hand side contain some domain identifier
   (either of the host itself or otherwise) such that the generator of
   the message identifier can guarantee the uniqueness of the left hand
   side within the scope of that domain.

Where known, the Message-ID algorithms for known programs are given on the separate pages for those programs.

Sample Header

This is an (incomplete) excerpt from an email header:

Received: from lists.securityfocus.com (lists.securityfocus.com [205.206.231.19])
        by outgoing2.securityfocus.com (Postfix) with QMQP
        id 7E9971460C9; Mon,  9 Jan 2006 08:01:36 -0700 (MST)
Mailing-List: contact forensics-help@securityfocus.com; run by ezmlm
Precedence: bulk
List-Id: <forensics.list-id.securityfocus.com>
List-Post: <mailto:forensics@securityfocus.com>
List-Help: <mailto:forensics-help@securityfocus.com>
List-Unsubscribe: <mailto:forensics-unsubscribe@securityfocus.com>
List-Subscribe: <mailto:forensics-subscribe@securityfocus.com>
Delivered-To: mailing list forensics@securityfocus.com
Delivered-To: moderator for forensics@securityfocus.com
Received: (qmail 20564 invoked from network); 5 Jan 2006 16:11:57 -0000
From: YJesus <yjesus@security-projects.com>
To: forensics@securityfocus.com
Subject: New Tool : Unhide
User-Agent: KMail/1.9
MIME-Version: 1.0
Content-Disposition: inline
Date: Thu, 5 Jan 2006 16:41:30 +0100
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
Message-Id: <200601051641.31830.yjesus@security-projects.com>
X-HE-Spam-Level: /
X-HE-Spam-Score: 0.0
X-HE-Virus-Scanned: yes
Status: RO
Content-Length: 586
Lines: 26

External Links

Retrieved from "http://forensicswiki.org/index.php?title=Cell_phones&oldid=2826"