Which of the following is an outputspreading technique that spammers use to manipulate reputation scores and
defeat filters? (Select the best answer.)

A.
phishing

B.
snowshoe spam

C.
waterfalling

D.
listwashing

Explanation:
Of the available choices, snowshoe spam is an outputspreading technique that spammers use to manipulate
reputation scores and defeat filters. Snowshoe spammers establish many false company names and identities,
often with unique post office addresses and telephone numbers, so that reputation filters do not perceive the
source of the spam as a threat. In addition, the spam output is spread across multiple IP addresses and
domain names in order to defeat blacklists.
The Cisco Context Adaptive Scanning Engine (CASE) on a Cisco Email Security Appliance (ESA) is a
contextual analysis technology that is intended to detect email threats, such as snowshoe spam, as they are
received. CASE checks the reputation of email senders, scans the content of email messages, and analyzes
the construction of email messages. As part of this process, CASE submits the email sender to the Cisco
SenderBase Network, which contains data on hundreds of thousands of email networks. The sender is
assigned a score based on this information. The content of the email messaging is scanned because it could
contain language, links, or a call to action that is indicative of a phishing scam.
Phishing is a social engineering technique in which a malicious person uses a seemingly legitimate electronic
communication, such as email or a webpage, in an attempt to dupe a user into submitting personal information,
such as a Social Security number (SSN), account login information, or financial information. To mitigate the
effects of a phishing attack, users should use email clients and web browsers that provide phishing filters. In
addition, users should also be wary of any unsolicited email or web content that requests personal information.
The CASE on a Cisco ESA appliance is capable of detecting phishing scams.
Listwashing is a spammer technique of cleaning lists of email recipients who complain about spam but without
stopping the spam from being sent to other recipients who do not complain. Listwashing is similar to an optout
address policy, meaning that email addresses are included in the list without the permission of the email
address owner and only removed if the owner complains.
Waterfalling is a spammer technique of cleaning lists of email recipients by sending the lists through multiple
email service providers. Spammers with bad lists use this technique to uncover email addresses that bounce or
that result in complaints against the spammer. The spammer can then remove those email addresses from the
list, which increases the likelihood that spam will be delivered to the remaining recipients.

Cisco: Cisco Email Security Appliance Data Sheet
Spamhaus: Frequently Asked Questions (FAQ): Snowshoe Spamming