Pharming

:"For pharming in genetics, see pharming (genetics)." "For pharming in drug abuse, see pharming parties."

Pharming (pronounced farming) is a hacker's attack aiming to redirect a website's traffic to another, bogus website. Pharming can be conducted either by changing the hosts file on a victim’s computer or by exploitation of a vulnerability in DNS server software. DNS servers are computers responsible for resolving Internet names into their real addresses — they are the "signposts" of the Internet. Compromised DNS servers are sometimes referred to as "poisoned". The term pharming is a word play on farming and phishing. The term phishing refers to social engineering attacks to obtain access credentials such as user names and passwords. In recent years both pharming and phishing have been used to steal identity information. Pharming has become of major concern to businesses hosting ecommerce and online banking websites. Sophisticated measures known as anti-pharming are required to protect against this serious threat. Antivirus software and spyware removal software cannot protect against pharming.

Pharming vulnerability at home

While malicious domain name resolution can result from compromises in the large numbers of trusted nodes that participate in a name lookup, the most vulnerable points of compromise are near the leaves of the internet. For instance, incorrect entries in a desktop computer's "Hosts file", which circumvents name lookup with its own local name to IP address mapping, is a popular target for malware. Once rewritten, a legitimate request for a sensitive website can direct the user to a fraudulent copy. Desktops are often better targets for pharming because they receive poorer administration than most internet servers.

More worrisome than host file attacks is the compromise of a local network router. [cite news
url=http://www.cs.indiana.edu/~atsow/mal-router
title=Can You Trust a Wireless Router?
date=February 24, 2006
publisher=Indiana University Bloomington] Since most routers specify a trusted DNS to clients as they join the network, misinformation here will spoil lookups for the entire LAN. Unlike host file rewrites, local router compromise is difficult to detect. Routers can pass bad DNS information in two ways: malconfiguration of existing settings or wholesale rewrite of embedded software (aka firmware). Nearly every router allows its administrator to specify a particular trusted DNS in place of the one suggested by an upstream node (e.g., the ISP). An attacker could specify a DNS server under his control instead of a legitimate one. All subsequent resolutions will go through the bad server. A scenario involving malicious JavaScript that changes the router's DNS server is called Drive-By Pharming and realized by Stamm, Ramzan and Jakobsson in a December 2006 technical report. [cite news
url=http://www.cs.indiana.edu/cgi-bin/techreports/TRNNN.cgi?trnum=TR641
title=Drive-By Pharming
date=December 13, 2006
publisher=Indiana University Bloomington]

Alternatively, many routers have the ability to replace their firmware (i.e. the internal software that executes the device's more complex services). Like malware on desktop systems, a firmware replacement can be very difficult to detect. A stealthy implementation will appear to behave the same as the manufacturer's firmware; the administration page will look the same, settings will appear correct, etc. Pharming is only one of many attacks that malicious firmware can mount; others include eavesdropping, active man in the middle attacks, and traffic logging. Like misconfiguration, the entire LAN is subject to these actions.

By themselves, these pharming approaches have only academic interest. However, the ubiquity of consumer grade wireless routers present a massive vulnerability. Administrative access is available wirelessly on most of these devices. Moreover, since these routers often work with their default settings, administrative passwords are commonly unchanged. Even when altered, many are guessed quickly through dictionary attacks, since most consumer grade routers don't introduce timing penalties for incorrect login attempts. Once administrative access is granted, all of the router's settings including the firmware itself may be altered. These factors conspire to make drive-by router compromise a clear and present threat. These attacks are difficult to trace because they occur outside the home or small office "and" outside the internet.

Instances of pharming

In January 2005, the domain name for a large New York ISP, Panix, was hijacked to point to a site in Australia. No financial losses are known.

In January 2008, Symantec reported a drive-by pharming incident directed against a Mexican bank in which the DNS settings on a customer's home router was changed after receipt of an e-mail that appeared to be from a legitimate Spanish-language greeting card company. [cite news
url=http://www.networkworld.com/news/2008/012208-drive-by-pharming.html
last=Messmer
first=Ellen
title=First case of "drive-by pharming" identified in the wild
date=January 22, 2008
publisher=Network World]

Controversy over the use of the term

The term "pharming" is controversial within the field. At a conference organized by the Anti-Phishing Working Group, Phillip Hallam-Baker denounced the term as "a marketing neologism designed to convince banks to buy a new set of security services."

ee also

* Anti-pharming
* Page hijacking
* Phishing
* DNS cache poisoning
* Mutual authentication

References

* cite news | url=http://www.windowsitpro.com/Article/ArticleID/46789/46789.html?Ad=1
title=Security: Phishing and Pharming
date=June 22, 2005
publisher=Windows IT Pro Magazine
* cite news | url=http://www.csoonline.com/talkback/071905.html
title=How Can We Stop Phishing and Pharming Scams?
date=July 20, 2005
publisher=CSO Magazine

External links

* [http://www.trusteer.com/docs/bind9dns.html BIND 9 DNS Cache Poisoning (DNS Pharming Attack)] - Discovered by Amit Klein (Trusteer)
* [http://www.digitalstakeout.com DigitalStakeout: Anti-Pharming Service Provider]
* [http://www.ngssoftware.com/papers/ThePharmingGuide.pdf "The Pharming Guide" by Gunter Ollmann]
* [http://reviews.zdnet.co.uk/software/internet/0,39024165,39188617,00.htm ZD Net Article "Alarm over "Pharming" Attacks]
* [http://www.wired.com/news/infostructure/0,1377,66853,00.html Wired News: Pharming Out-Scams Phishing]
* [http://www.networkworld.com/columnists/2005/062705edit.html Network World Article on New Anti-Pharming Technology]
* [http://www.eweek.com/article2/0,1759,1791152,00.asp eWeek article on the Hushmail.com DNS pharming attack]
* [http://www.pharming.org pharming.org: Describes current state of the art in solutions to the pharming problem, and also has a list of sites that are and are not Pharming Conscious (PhC)]
* [http://www.csoonline.com/read/100105/pharm.html After Phishing? Pharming!]
* [http://www.safetyoninternet.com Safety on Internet]