Phishing

URL Obscuring

COEN 252 Computer ForensicsPhishingThomas Schwarz, S.J. 2006

URL ObscuringInternet based criminal activity that subverts web technology:Phishing (fraud)Traffic redirectionHosting of illegal sitesChild pornography

URL ObscuringInternet based fraud is gaining quickly in importance.Phishing: The practice of enticing victims with spoofed email to visit a fraudulent webpage.http://www.antiphishing.org/

URL ObscuringTechnical Subterfuge:Plants crimeware onto PCs.Example: Vulnerable web browser executes remote script at a criminal website.Just staying away from porn no longer protects you.Payload:Use Trojan keylogger spyware.Search for financial data and send it to an untraceable email addressURL ObscuringSocial Engineering:Target receives e-mail pretending to be from an institution inviting to go to the institutions website.Following the link leads to a spoofed website, which gathers data.It is possible to establish a web-presence without any links:Establish website with stolen / gift credit card.Use email to send harvested information to an untraceable account, etc.Connect through public networks.URL ObscuringPhishingTargets general populationThrives even with very low success rateSpear PhishingTargets individualsMore sophisticated and more expensiveIndividual success has higher valueURL Obscuring: Phishing Example

Visible Link: https://www.usa.visa.com/personal/secure_with_visa/index.html?t=h1_/index.html Actual Link: http://www.verified-web-us.com/Visa%20USA%20%20Personal%20%20Protect%20Your%20Card.htmActual website IP: 209.35.123.41 Uses Java program to overwrite the visible address bar in the window:URL Obscuring:Phishing Example

Phishing TendenciesPhishs currently are very unsophisticatedSophistication does not yield much better success rateURL ObscuringPhishs need to hide web-serversURL ObscuringJavascript or other active web-technology overwrites URL fieldno longer possible in latest browsersOther techniques to hide web-server address Use hosts fileHiding illegal web-server at legal siteHijacking site to host pages.

URL BasicsPhishs can use obscure features of URL.URL consists of three parts:ServiceAddress of serverLocation of resource.

http://www.cse.scu.edu/~tschwarz/coen252_03/Lectures/URLObscuring.htmlURL BasicsScheme, colon double forward slash.An optional user name and password. The internet domain name RCF1037 format IP address as a set of four decimal digits.Port number in decimal notation. (Optional)Path + communication data. http://tschwarz:[email protected]/~tschwarz/coen252_03/Lectures/URLObscuring.html http://www.google.com/search?hl=en&ie=UTF-8&q=phishingObscuring URL AddressesEmbed URL in other documentsUse features in those documents to not show complete URLhttp://[email protected]/~tschwarz/coen252_03/index.html URL rules interpret this as a userid.Hide this portion of the URL.Obscuring URL AddressesUse the password field.www.scu.edu has IP address 129.210.2.1.Some browsers accept the decimal value 129*256**3 + 210*256**2 + 2*256 + 1 = 2178023937 for the IP address.http://www.usfca.edu@2178023937 Works as a link.Does not work directly in later versions of IEObscuring URL Addresseshttp://[email protected] works.Hide the ASCI encoding of @:http://www.usfca.edu%40129.210.2.1Or just break up the name:http://www.usfca.edu%40%127%167w.scu.eduOr use active page technologies (javascript, ) to create fake links.

Obscuring URL AddressesIDN International Domain NamesNon-english Unicode characters are encoded as basic ASCII strings:punycodepunycode examplebcher.ch encoded as xn- - bcher kva.chHomographs: Characters from different alphabets look the samePotential URL Obscuring Register paypal.com, where one a comes from a different alphabet.

Obscuring URL AddressesPadding URLs.. means go up create directory http://129.210.2.1/.../../.../../.../../.../error.html

Obscuring URL AddressesRedirectionDirect target redirects to main siteChances of main site getting shut down is lessTechnologiesPage-based redirectionAdd meta tag to head section

Server-based redirectionApache: httpd.conf with a redirect statementRedirection via vulnerable websites2006 eBay run a script that redirected based on query string to any site.'Enroll your card with Verified By Visa program'2004 Phish sends SPAM consisting of a single image:

'Enroll your card with Verified By Visa program'The whole text is a single image, linked to the correct citi URL.If the mouse hovers over the image, it displays the correct citi URL.But surrounded by an HTML box that leads to the phishing website.'Enroll your card with Verified By Visa program'Target webpage has an address bar that is overwritten with a picture with a different URL.Go to www.antiphishing.org .

PhishingPhishers now use bogus https techniques.Exploiting browser flaws to display secure icon.Hacking legitimate sites or frames from these sites directly.Purchase and present certificates for sites that are named in resemblance of the target sites.The SSL lock icon is no longer a guarantee for a legitimate site.

Registrar Impersonation Phishing AttacksPhisher sets up a bogus registrar customer portalPhisher composes email correspondence from registrarPhisher sends email to the contact email addresses for a domain nameVictims visit bogus registrar customer portal and disclose login credentialsPhisher collects account credentials for subsequent misuseRegistrar Impersonation Phishing AttacksDomain name registration information is open to the publicE.g. whois for windows or linux/unixAdversary can use this information (plus web) in order to target potential victimsFor example, those whose registration is close to expirationThe information is also used to enhance the credibility of the messageUse whois

Registrar Impersonation Phishing AttacksOnce authentication information is obtainedModify DNS records to point to name servers under attackers controlMX: Points to mail hosts under attackers control and use them to send spam, The victim was trustedAAAA or A: To point to systems under attacker controlTo host phony contentTo provide false authentication portals

Registrar Impersonation Phishing AttacksFast Flux attacksFully qualified domain name has multiple (hundreds or even thousands) IP addresses assigned to it.Registrar Impersonation Phishing AttacksCounter measures taken:Registrars limit open information severelyShould not use email to communicate with clientsHiding HostsName Look-Up:OS checks HOST file first.Can use HOST file to block out certain sitesadserversAffects a single machine.

OSLocationLinux/etc/hostsWin95/98/MEC:\windows\hostsWin NT/2000/XP ProC:\winnt\systems32\etc\hostsWin XP HomeC:\windows\system32\drivers\etc\hosts

Subverting IP Look-UpIn general, not used for phishing.Economic DamageHillary for Senate campaign attack.Hiding illegal websites. (Kiddie Porn)DNS Server Sabotage IP Forwarding

Subverting IP Look-UpPort ForwardingURLs allow port numbers.Legitimate business at default port number.Illegitimate at an obscure port number.Screen clicksEmbed small picture.Single pixel.Forward from picture to the illegitimate site.Easily detected in HTML source code.Password screensDepending on access control, access to different sites.

Phisher-FinderCarefully investigate the message to find the URL.Do not expect this to be successful unless the phisher is low-tech.Capture network traffic with Ethereal to find the actual URL / IP address.Use Sam Spade or similar tools to collect data about the IP address.Phisher-FinderCapture network traffic with Ethereal when going to the site.This could be dangerous.Disable active webpages.Do not use IE (too popular).Look at the http messages actually transmitted.Expect some cgi etc. script.

Phisher-FinderInvestigation now needs to find the person that has access to the website.This is were you can expect to loose the trace.The data entered can be transmitted in various forms, such as anonymous email.For example, they can be sent to a free email account.IPS usually has the IP data of the computer from which the account was set up and from which the account was recently accessed.Perpetrator can use publicly available computers and / or unencrypted wireless access points.Investigator is usually left with vague geographical data.