http://www.csc.gatech.edu/copeland/jac/8843/ Prof. John A. Copeland [email protected] 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 MIME Headers Multipurpose Internet Mail Extensions (MIME) RFC 1341 and RFC 1521 • MIME -Version: • Content-Description: version number 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 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 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 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 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 Received: from gatech.edu (gatech.edu [22.214.171.124]) by mail.ee.gatech.edu (8.12.9/8.12.9) with ESMTP id h7JMHlYk014613 for <[email protected]>; Tue, 19 Aug 2003 18:43:22 -0400 (EDT) Received: from STUDENT235 (registration15.pbf.gatech.edu [126.96.36.199]) by gatech.edu (8.12.9/8.12.9) with ESMTP id h7JKhbpf022649 for <[email protected]>; Tue, 19 Aug 2003 16:43:39 -0400 (EDT) Message-Id: <[email protected]> From: <[email protected]> To: <[email protected]> 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 Return-Path: <[email protected]> Received: from hubert.mail.atl.earthlink.net (hubert.mail.atl.earthlink.net [188.8.131.52]) by mail.ee.gatech.edu (8.12.10/8.12.9) with ESMTP id h8T36j6w021206 for <[email protected]>; Sun, 28 Sep 2003 23:06:46 -0400 (EDT) Received: from 12-240-168-97.client.attbi.com ([184.108.40.206]) by carus.mspring.net (Earthlink Mail Service) with SMTP id 1a3OmZ7xt3Nl5tW0 for <[email protected]>; Sun, 28 Sep 2003 23:06:41 -0400 (EDT) Received: from [220.127.116.11] by 12-240-168-97.client.attbi.com with SMTP; Mon, 29 Sep 2003 03:03:44 Message-ID: [email protected] From: "Jerrold Hedrick" <[email protected]> To: <[email protected]> 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 ggsbwmzsdg hpb duqicsj qtsaxym ae zizssn vs tqcjbfmmgyogkpkn h nxw http://www.broadcastemailing.com 8 # nslookup 18.104.22.168 [IP address from “Rcvd:” header] *** eeserv.ee.gatech.edu can't find 22.214.171.124: Non-existent host/domain [from www.geektools.com] Final results for 126.96.36.199 obtained from whois.arin.net. OrgName: DoD Network Information Center OrgID: DNIC Address: 7990 Science Applications Ct Address: M/S CV 50 City: Vienna StateProv: VA [false email source address] ------------------------------------------------------------------------# nslookup www.broadcastemailing.com [from content] Name: www.broadcastemailing.com Address: 188.8.131.52 inetnum: 184.108.40.206 - 220.127.116.11 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 [actual Web location] 9 From: "Citibank Support" <[email protected]> To: "Jacom" <[email protected]> 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: <http://18.104.22.168/verification/>] 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. Note the lack of the “Padlock” symbol. HTTPS (TLS) is not being used because they have no X509 certificate. Look at Page Source Code - check links: (note directory named “scam”) <td height="66"> <p><img src="citi44a.gif" width="61" height="44"> <img src="file:///F|/scam/scripts2/scripts/w4_0.gif" width="80" height="25"> <img src="file:///F|/scam/scripts2/scripts/m4_1.gif" width="77" height="25” <p><font color="#0000CC"><b><font size="2" color="#000099">HOME | ACCOUNTS | PAYMENTS & TRANSFERS | INVESTMENTS | ACCOUNT SERVICING</font></b></font> </p></td> whois.apnic.net. Results:% Whois data copyright terms http://www.apnic.net/db/dbcopyright.html inetnum: 22.214.171.124 - 126.96.36.199 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: [email protected] 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: [email protected] trouble: send spam reports to [email protected] trouble: and abuse reports to [email protected] trouble: Please include detailed information and trouble: times in GMT+8 Received: from capitalgroup.ru ([188.8.131.52]) Date: Wed, 22 Sep 2004 15:01:44 +0000 To: [email protected] From: "Lillie Haywood" <[email protected]> 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: <http://TNIKHMCYV.adwarebde.com/?id=02025><img src="http://www.adwarebde.com/m2.gif"> 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. % nslookup -sil www.ad-eliminator.com Name: www.ad-eliminator.com Address: 184.108.40.206 whois.apnic.net. [ results from www.geektools.com 220.127.116.11 ] Results: % [whois.apnic.net node-2] % Whois data copyright terms http://www.apnic.net/db/dbcopyright.html inetnum: 18.104.22.168 - 22.214.171.124 netname: UNICOM descr: China United Telecommunications Corporation descr: Beijing Railway Station East Avenue country: CN mnt-lower: MAINT-CN-CNNIC-UNICOM changed: [email protected] 20010817 changed: [email protected] 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: [email protected] Email Relaying (should be prohibited) MS or sender earthlink.com MS MS receiver gatech.edu aol.com Allowed Email Forwarding MS sender MS sender receiver earthlink.com gatech.edu MS receiver aol.com MS = Mail Server 15 Data Compression (as in V.21bis modems) “the_thin_thinker” t - 84 h - 104 th - 256 he - 257 hi- 264 e - 101 _ - 32 i - 105 n - 110 e_ - 258 _t - 259 in - 261 n_ - 262 _th - 263 ink - 265 thi - 260 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. “84, 104, 101, 32, 256, 105,110, 259, 104, 261 . . .” 16 Security Wire Perspectives, Sept 20, 2004 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.