1. http://www.csc.gatech.edu/copeland/jac/8843/ Prof. John A. Copeland john.copeland@ece.gatech.edu 404 894-5177 fax 404 894-0035 Office: GCATT Bldg 579 email or call for office visit, or call Kathy Cheek, 404 894-5696 Chapter 5b - Secure/Multipurpose Internet Mail Extensions S/MIME

2. MIME Headers Multipurpose Internet Mail Extensions (MIME) RFC 1341 and RFC 1521 MIME -Version:version number Content-Description: human-readable string Content-ID:unique identifier Content-Transfer-Encoding:body encoding >ASCII (Plain, quoted-printable, or Richtext) >Binary (base64) Content-Type:nature of the message >Image (gif, jpeg), Video (mpeg), >Application (Postscript, octet-stream > A.S.Tanenbaum, "Computer Networks," (3rd ed.) p.653 2

3. Simple Mail Transfer Protocol (SMTP, RFC 822) SMTP Limitations - Can not transmit, or has a problem with: executable files, or other binary files (jpeg image). “national language” characters (non-ASCII) messages over a certain size ASCII to EBCDIC translation problems lines longer than a certain length (72 to 254 characters) MIME Defined Five New Headers MIME-Version. Must be “1.0” -> RFC 2045, RFC 2046 Content-Type. More types being added by developers (application/word) Content-Transfer-Encoding. How message has been encoded (radix-64) Content-ID. Unique identifying character string. Content Description. Needed when content is not readable text (e.g.,mpeg) Carnonical Form: Standard format for use between systems ( not a “native” format - GIF). 3

4. Secure/MIME Can “sign” and/or encrypt messages Functions: Enveloped Data: Encrypted content and encrypted session keys for recipients. Signed Data: Message Digest encrypted with private key of “signer.” Clear-Signed Data: Signed but not encrypted. Signed and Enveloped Data: Various orderings for encrypting and signing. Algorithms Used Message Digesting: SHA-1 and MDS Digital Signatures: DSS Secret-Key Encryption: Triple-DES, RC2/40 (exportable) Public-Private Key Encryption: RSA with key sizes of 512 and 1024 bits, and Diffie-Hellman (for session keys). 4

5. S/MIME - User Agent Role S/MIME uses Public-Key Certificates - X.509 version 3 signed by Certification Authority Functions: Key Generation - Diffie-Hellman, DSS, and RSA key-pairs. Registration - Public keys must be registered with X.509 CA. Certificate Storage - Local (as in browser application) for different services. Signed and Enveloped Data: Various orderings for encrypting and signing. Example: Verisign (www.verisign.com) Class-1 Buyer’s email address confirmed by emailing vital info. Class-2 Postal address is confirmed as well, and data checked against diectories. Class-3 Buyer must appear in person, or send notarized documents. 5

6. General Email Problems SNMP Headers Can be used to check email routing, but not reliable (spoofing, NAT,...) Can reveal your IP address, mail server to receipients Content Poisons: Attachments that are executable files (viruses, Worms, Back Doors,...) HTML encoded mail has all the threats of an untrusted Web site Links can execute code FTP links can give away your email address, if used as password Hidden keys can identify the address of the message, ID of receipient Spammers use unwitting mail servers for exploding and relaying email, hiding their identity This requires “Relaying Prohibited,” makes sending email harder from the road 6

7. Received: from gatech.edu (gatech.edu [130.207.244.244]) by mail.ee.gatech.edu (8.12.9/8.12.9) with ESMTP id h7JMHlYk014613 for ; Tue, 19 Aug 2003 18:43:22 -0400 (EDT) Received: from STUDENT235 (registration15.pbf.gatech.edu [130.207.41.235]) by gatech.edu (8.12.9/8.12.9) with ESMTP id h7JKhbpf022649 for ; Tue, 19 Aug 2003 16:43:39 -0400 (EDT) Message-Id: From: To: Subject: Re: Re: My details Date: Tue, 19 Aug 2003 16:42:16 --0400 X-MailScanner: Found to be clean X-Mailer: Microsoft Outlook Express 6.00.2600.0000 MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="_NextPart_000_01EA719F" X-Virus-Scanned: by amavisd-new X-SPAM: NO See the attached file for details Content-Type: application/octet-stream; name="movie0045.pif" Attachment converted: movie0045.mov.pif 7

8. Return-Path: Received: from hubert.mail.atl.earthlink.net (hubert.mail.atl.earthlink.net [207.69.200.45]) by mail.ee.gatech.edu (8.12.10/8.12.9) with ESMTP id h8T36j6w021206 for ; Sun, 28 Sep 2003 23:06:46 -0400 (EDT) Received: from 12-240-168-97.client.attbi.com ([12.240.168.97]) by carus.mspring.net (Earthlink Mail Service) with SMTP id 1a3OmZ7xt3Nl5tW0 for ; Sun, 28 Sep 2003 23:06:41 -0400 (EDT) Received: from [22.239.60.151] by 12-240-168-97.client.attbi.com with SMTP; Mon, 29 Sep 2003 03:03:44 -0100 Message-ID: y52v0-v-s7-5$2fa-sf-kchf@q8mu3zfs.5.jsw From: "Jerrold Hedrick" To: Subject: Re: Email Advertise to 0.8 Million People - $87 Date: Mon, 29 Sep 03 03:03:44 GMT X-Mailer: eGroups Message Poster MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="B70E7F2___1DED4_.____0E" X-Virus-Scanned: by amavisd-new X-SPAM: NO Content-Type: text/plain; Broadcast Email Advertise to 28.9 Million People - $129 http://www.broadcastemailing.com ggsbwmzsdg hpb duqicsj qtsaxym ae zizssn vs tqcjbfmmgyogkpkn h nxw 8

9. # nslookup 22.239.60.151 [IP address from “Rcvd:” header] *** eeserv.ee.gatech.edu can't find 22.239.60.151: Non-existent host/domain [from www.geektools.com ] Final results for 22.239.201.237 obtained from whois.arin.net. OrgName: DoD Network Information Center [false email source address] OrgID: DNIC Address: 7990 Science Applications Ct Address: M/S CV 50 City: Vienna StateProv: VA ------------------------------------------------------------------------- # nslookup www.broadcastemailing.com [from content] Name: www.broadcastemailing.com Address: 202.63.201.237 inetnum: 202.63.192.0 - 202.63.223.255 [actual Web location] descr: CubeXS Private Limited descr: Internet Service Provider descr: Data Entry descr: Software House descr: 310-311 Kassam Court descr: B.C. 9, Block 5, Clifton descr: Karachi, Pakistan 9

10. From: "Citibank Support" To: "Jacom" Subject: ATTN: Security Update from Citibank MsgID# 92309245 Date: Wed, 22 Sep 2004 03:10:44 +0100 CITIBANK(R) “Phishing” Dear Citibank Customer: Recently there have been a large number computer terrorist attacks over our database server. In order to safeguard your account, we require that you update your Citibank ATM/Debit card PIN. This update is requested of you as a precautionary measure against fraud. Please note that we have no particular indications that your details have been compromised in any way. This process is mandatory, and if not completed within the nearest time your account may be subject to temporary suspension. Please make sure you have your Citibank ATM/Debit card and your login details at hand. To securely update your Citibank ATM/Debit card PIN please go to: Customer Verification Form [Note: the actual link is to: ] Please note that this update applies to your Citibank ATM/Debit card - which is linked directly to your checking account, not Citibank credit cards. Regards, Customer Support MsgID# 92309245 (C)2004 Citibank. Citibank, N.A., Citibank, F.S.B., Citibank (West), FSB. Member FDIC.Citibank and Arc Design is a registered service mark of Citicorp.

11. Look at Page Source Code - check links: (note directory named “scam”) <img src="file:///F|/scam/scripts2/scripts/m4_1.gif" width="77" height="25” HOME | ACCOUNTS | PAYMENTS & TRANSFERS | INVESTMENTS | ACCOUNT SERVICING Note the lack of the “Padlock” symbol. HTTPS (TLS) is not being used because they have no X509 certificate.

12. whois.apnic.net. Results:% Whois data copyright terms http://www.apnic.net/db/dbcopyright.html inetnum: 219.138.0.0 - 219.140.255.255 netname: CHINANET-HB descr: CHINANET hubei province network descr: China Telecom descr: A12,Xin-Jie-Kou-Wai Street descr: Beijing 100088 country: CN admin-c: CH93-AP tech-c: CHA1-AP mnt-by: MAINT-CHINANET mnt-lower: MAINT-CN-CHINANET-HB changed: hostmaster@ns.chinanet.cn.net 20020521 status: ALLOCATED NON-PORTABLE source: APNIC role: CHINANET HB ADMIN address: 8th floor of JinGuang Building address: #232 of Macao Road address: HanKou Wuhan Hubei Province address: P.R.China country: CN phone: +86 27 82862199 fax-no: +86 27 82861499 e-mail: ip_admin_hb@public.wh.hb.cn trouble: send spam reports to spam_hb@public.wh.hb.cn trouble: and abuse reports to abuse_hb@public.wh.hb.cn trouble: Please include detailed information and trouble: times in GMT+8

13. Date: Wed, 22 Sep 2004 15:01:44 +0000 To: jacopeland3@mindspring.com From: "Lillie Haywood" Subject: Better than Norton, and Symantec for spyware z5 X-ELNK-AV: 0 dodd compriest stiffing thwacks. designer azyme glebous outgrowths unconsonant unsoluble dyscrasic. phylactery docking javeline uncommandedness palmitinic checkrowed findal teretial. misshaped diabolarch aprication marsupia parallelotropism. Clicking on the “Scan” button (or anywhere in the image) takes you to: Notice that the serial code “02025” or system “TNIKHMCY” could be codes which may validate your IP address. The random words in the text are to get past a Basian spam filter. They could not actually “scan” my Macintosh computer, which has no spyware. Received: from capitalgroup.ru ([221.192.242.56])

14. whois.apnic.net. [ results from www.geektools.com 61.240.131.217 ] Results: % [whois.apnic.net node-2] % Whois data copyright terms http://www.apnic.net/db/dbcopyright.html inetnum: 61.240.0.0 - 61.243.255.255 netname: UNICOM descr: China United Telecommunications Corporation descr: Beijing Railway Station East Avenue country: CN mnt-lower: MAINT-CN-CNNIC-UNICOM changed: hostmaster@apnic.net 20010817 changed: ipas@cnnic.net.cn 20010828 status: ALLOCATED PORTABLE source: APNIC person: RenYong Xu address: 911 Room,Xin Tong Center,No.8 address: Beijing Railway Station East Avenue, address: Beijing,PRC. country: CN phone: +86-10-6527-8866 fax-no: +86-10-6526-0124 e-mail: ip_address@cnuninet.com % nslookup -sil www.ad-eliminator.com Name: www.ad-eliminator.com Address: 61.240.131.217

15. earthlink.comgatech.edu aol.com MS MS or sender MS MS = Mail Server receiver Email Relaying (should be prohibited) 15 earthlink.comgatech.edu aol.com MS sender MS receiver Allowed Email Forwarding receiver sender MS

16. Data Compression (as in V.21bis modems) “the_thin_thinker” 16 t - 84h - 104 th - 256 e - 101_ - 32 he - 257e_ - 258_t - 259 “84, 104, 101, 32, 256, 105,110, 259, 104, 261...” thi - 260 i - 105 in - 261 n - 110 n_ - 262 _th - 263 hi- 264 ink - 265 Dictionary has 4096 entries (12-bit tokens). Entries 0 to 255 represent a single byte (permanent). Other entries are filled after a string match: = string plus first unmatched character. Message is encoded (compressed) by sending 12-bit tokens represent multiple bytes. Note that tokens 256, 259, and 261 below represent 2 bytes (16 bits) by a 12-bit token.

17. In fact, of the targeted attacks Symantec detected in the last six months, the majority were against e-commerce companies, including financial institutions. Small business received the second highest number of attacks. "We're no longer talking strictly about the male teenager with the low moral compass, or the hactivist, who defaces sites or uses malicious code or worms against those on one side in a political conflict," said Vincent Weafer, senior director of Symantec Security Response. "These people are targeting e-commerce, and they are often backed by organized crime.” The average time period between the disclosure of a vulnerability and its first exploit by hackers collapsed from several weeks in past reports to less than six days in the first half of 2004. Security Wire Perspectives, Sept 20, 2004