The "No Network is 100% Secure" series
- Phishing -
A White Paper
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What is phishing?: Phishing is an attempt to steal personal data. 
The term comes from "Fishing for information".
SMS phishing:  SMSishing) occurs when you receive an SMS message that is 
purportedly sent from a reputable source, such as your bank, asking for personal 
details.
How is phishing accomplished?: 
Several popular methods are used to illegally acquire sensitive or private 
information such as bank details, login information or personal details. The 
delivery method is usually via electronic e-mail. These messages usually direct 
victims to a spoofed web site or otherwise get you to divulge private information 
(e.g., password, credit card, or other information). The perpetrators then 
use this private information to commit various types of fraud such as identity theft.
Why do people fall for these phishing scams?: 
Phishing scams are social engineering tools designed to induce panic in the 
reader. These scams attempt to trick recipients into responding or clicking 
immediately, by claiming they will lose something (e.g., email, bank account). Such 
a claim is always indicative of a phishing scam, as responsible companies and 
organizations will never take these types of actions via email.
How does one avoid becoming a phishing victim?: Most people tend to be 
trusting of their fellow man.  But most people do not understand that the Internet 
is like the old Wild West...  totally lawless with robbers, thugs and highway men at 
every turn. Until computer users become "street smart" and understand that 
the rules of polite society do not apply on the Internet, there will be 
victims a-plenty for the World's cyber criminals. The first rule of self-protection 
is "trust no one and nothing that comes to you via the Internet".  Ignore this 
rule at your peril
Here are a few specifics: 
Always be suspicious of any email message that asks you to enter or verify personal 
information, through a web site or by replying to the message itself. Never reply 
to or click the links in a message. If you feel the message may be legitimate, go 
directly to the company's web site (i.e., type the real URL into your browser) or 
contact the company to see if you really do need to take the action described in 
the email message. Avoid providing any information on web sites that can not be 
authenticated with a Verisign certificate.  If you don't know what this is, my advice 
would be to never provide any personal information to any web site period.
When you recognize a phishing message, delete the email message from your Inbox, 
and then empty it from the deleted items folder to avoid accidentally accessing 
the web sites it points to.
Always read your email as plain text. Phishing messages often contain clickable 
images that look legitimate; by reading messages in plain text, you can see the 
URLs that any images point to. Additionally, when you allow your mail client to 
read HTML or other non-text-only formatting, attackers can take advantage of your 
mail client's ability to execute code, which leaves your computer vulnerable to 
viruses, worms, and Trojans. 
Cautionary notes: Reading email as plain text is a general best practice 
that, while avoiding some phishing attempts, won't avoid them all. Some legitimate 
sites use redirect scripts that don't check the redirects. Consequently, phishing 
perpetrators can use these scripts to redirect from legitimate sites to their fake 
sites.
Another tactic is to use a homograph attack, which, due to International Domain Name 
(IDN) support in modern browsers, allows attackers to use different language 
character sets to produce URLs that look remarkably like the authentic ones. 
This deception uses a technology known as punycode. These web sites may very 
well have Verisign certificates and could look completely legitimate.
Bottom line: Trust has gone out the window when you follow links in email or 
on Web sites. There's no longer a way to be sure that the domain name you're visiting 
is the one you think you are unless you check the URL out in Terminal or have 
multiple anti-spoofing and anti-phishing browser plug-ins installed. When it comes to 
entering personal information on a web site when asked to do so, my advice would be: 
just don't do it!
Why should IT Managers care about phishing?: Phishing is typically a one-on-one 
attack.  So why would an enterprise network manager care about these activities? 
Phishing is often geared towards obtaining a legitimate username and password 
in a computer network somewhere. And as you may know, the best way to defend against 
hackers is to never allow them to gain access to your network.  Once a miscreant 
gains login access to your network, they are half way there to gaining root access. 
This is particularly problematic in large networks that use login 
authentication methods such as 
NIS, active directory, pam and so on. Once they are "inside", they can bypass 
protections such as firewalls and intrustion detection systems (IDS) making 
it much easier to wreak havoc in your network.
My ISP has tens of thousands of users and even if only two or three fall for a 
phishing scam, it can cause major problems for them.  For example, having a legit 
username and password allows them to access the ISP mail server for the purpose 
of sending bulk spam e-mail.  At the very least, this causes the victim e-mail 
server(s) to be blacklisted (blocked) by most larger ISPs and company networks, 
greatly interfering with your ability to conduct business. And depending on how 
robust your mail server hardware is, the attack could also result in a DoS preventing 
legitimate e-mail to or from your company from being delivered.
With a username and password, hackers can also upload web site content that 
sends web surfers to porn sites and other web servers run by criminals.  And if 
your file protections are weak, hackers can also deface and otherwise compromise 
your company web site!  Just do a Google search on "porn sex midgets" or something 
like that and see how many government web sites, libraries, church sites, 
businesses and so on show up in the listing that host one or more porn site pages! 
Embarrassing, to say the least!
Can these attacks be seen?: If you don't have a professionally staffed, 
proactive NOC and/or if you 
are not actively monitoring server log files, probably not.  You're first indication 
may well be vague complaints by users that "the network is slow".  Depending 
on the severity of the break-in, your users may start seeing mail bouncing 
messages or other symptoms that will eventually be reported to IT support. Without 
the proper tools, these cyber criminals could be having a fine old time for hours or 
even days before you actually realize what's going on.  And by that time, 
the damage has been done and it's all over but the crying.
What symptoms should I look for?: A substantial increase in the server 
load average or the length of the mail queue would be two indications.
From my ISP: how do you spot if a phishing attack was successful?  You 
look in the maillogs and see two patterns:
1) A series of emails going to alphabetically-arranged usernames in a single domain.
2) A whole bunch of NDRs (non-delivery report), usually from messages sent to 
nonexistent addresses.
If you see those two, you're pretty sure you've got a spammer in your network.  
From there, it's a matter of tracking them down and knowing whether or not your 
users were recently targeted with a phishing email.
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Monitoring Basics 101 White Paper
Monitoring Basics 102 White Paper
Monitoring Basics 103 White Paper
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Shelfware White Paper
Outsourced IT White Paper
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Last modified March 25, 2009
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