|Lesson 6||SPAM |
|Objective||Identify the traits of email SPAM. |
What is Spam Email?
Email spam, commonly referred to as "junk mail," is unsolicited, often irrelevant or inappropriate messages sent over the Internet, typically to a large number of users, for the purposes of advertising, phishing, spreading malware, or other such objectives. The phenomenon is pervasive due to the relatively low cost of sending email compared to traditional mail, the ease of distributing to a large number of recipients, and the anonymity it offers the sender. Various traits and characteristics distinguish email spam from legitimate correspondence:
- Generic Salutations: Spam emails often employ generic greetings like "Dear User" or "Dear Customer," lacking personalized identification.
- Manipulative Phrasing: These emails may use urgent language ("Act now," "Immediate attention required") to create a sense of urgency.
- Promotional Content: Spam is frequently promotional in nature, often advertising products, services, or investment opportunities. 7
- Spelling and Grammar Errors: Poor syntax, spelling mistakes, and grammatical errors are commonplace, potentially to evade spam filters.
- URL Redirection: The email often includes hyperlinks that redirect to websites different from what they appear to represent, usually for phishing or malware deployment.
- Attachment Types: Suspicious file types such as `.exe`, `.zip`, or `.scr` may be included, often carrying malware.
- Header Anomalies: The header information might contain inconsistencies, such as a mismatch between the 'From' email address domain and the 'Reply-To' address.
- Bulk Addresses: Emails sent to a large number of recipients, often visible in the 'To' or 'CC' fields, are indicative of spam.
- IP Blacklisting: The originating IP address may be listed on public spam blacklists.
- Payload Analysis: The body content often includes base64-encoded data or obfuscated text aimed at bypassing text-based spam filters.
- HTML Malformation: Spam emails may contain poorly formed HTML tags or unnecessary HTML elements intended to obfuscate the message content.
- Frequency: Spam emails are typically sent in large volumes within a short time frame to maximize reach.
- Lack of Unsubscribe Option: Contrary to regulations like the CAN-SPAM Act in the United States, spam emails may not provide an option to unsubscribe.
- Evasion Tactics: Techniques like 'snowshoeing,' where spam is spread across many IPs and domains to dilute reputation metrics, are commonly employed.
- Sporadic Communication: Unlike legitimate services that have regular communication patterns, spam emails are often sent sporadically and unpredictably.
Understanding these traits is critical for both end-users and administrators in implementing effective anti-spam measures, which often involve multi-layered approaches combining content filtering, behavioral analysis, and continuously updated blacklists to adapt to evolving spam tactics.
Though not an acronym, SPAM does stand for something. To most users, SPAM stands for "annoyance," and for many users, "theft." In truth, SPAM is unsolicited email, usually commercial, delivered in bulk to a large number of users. SPAM, in addition to being unsolicited, has other problems. It wastes Internet bandwidth, because the same message is delivered to vast numbers of Internet users. It costs money for unwilling recipients who pay for Internet access, because they must download the email unnecessarily. Finally, it wastes computational time delivering the mail, and the storage space to hold it.
A spammer is anyone who sends SPAM. Spammers compile their mailing lists in a variety of ways; sometimes they purchase lists, but more often they simply harvest email addresses from Web sites and newsgroups.
Spammers import their email address lists into bulk mailing software. This software is able to deliver vast quantities of email extremely rapidly, often through short-term, free email accounts. They repeat this process hundreds of times a day,
and as you might suspect, the number of emails they send grows enormously.
Often spammers will forge their email headers so their mailings appear to come from other sources.
If the recipients retaliate, for example by complaining to their ISP, innocent sites might be held responsible for the spammers' actions.
Spammers who are more ethical use an "opt-in" methodology: rather than receiving an email out of nowhere, you must first request it.
The next lesson lists methods to combat SPAM.