A dictionary attack is an attempt to literally use every word in the dictionary as a means of identifying the password associated with an encrypted message or to gain control of a business network or even an email account. The idea is that by launching this sort of hacking strategy, the hacker can gain control of those resources and utilize them for whatever purpose he or she desires. While this approach can be very effective when a single word is used for the account security, the method is much less likely to succeed if the account owner has utilized a somewhat complicated pass phrase as security for the account.
The basic purpose of a dictionary attack is to engage in what is known as password cracking. For example, the attack may be launched to isolate the password associated with a specific email account. Once this is accomplished, the hacker can access the address book associated with that account and replicate the process with those addresses. The result of this email harvesting can be the creation of lists that are sold to marketers, or possibly use of those email accounts to create spam campaigns or spread viruses through means of seemingly innocuous attachments that appear to be from a trusted source.
In order to increase the potential for success, hackers will attempt to utilize as many words as possible when planning a dictionary attack. This means along with a traditional dictionary, the words found in various types of technical or industry related dictionaries and glossaries are added to the database used in the attempt. In addition, dictionaries for different languages are also added to the resource, which serves to increase the chances for associating a password with an email account or message.
A second process associated with a dictionary attack involves using software to scramble the contents of the dictionary as a means of locking in on what would seem to be random collections of letters. In some cases, the hacker may also include numbers and various types of punctuation in this random mix, making the chances of identifying more complex passwords a possibility.
An alternative form of a dictionary attack does not focus on identifying passwords as a means of gaining access to email accounts or networks. Instead, the hacker utilizes software to generate volumes of potential email addresses, then uses those addresses in some type of spam campaign. The idea is that while some of those generated addresses may not exist, others will be active and capable of receiving the spam message. This strategy may be used as a marketing ploy, or used as a way to spread viruses through an attachment to the spam email.