What is the motive of sending spam text [duplicate]

Question

Possible Duplicate:
Strange spam posts not making sense

I've many sites online and regularly I get the following type of spam text through "contact us" form even when containing Captchas. What could be the motive of sending such garbage? :

Submitted on Tuesday, October 11, 2011 - 10:43 Submitted by anonymous user: [188.143.232.33] Submitted values are:

Your Name: vlgktopsy Email-id: xoqvxh@hdqsrh.com Subject: QQLBMucIxgHjkAZxE Comments/Questions/Feedback: BqjVXf ujfyjtshjwos, [url=http://hwnjbrwibfme.com/]hwnjbrwibfme[/url], [link=http://rsxwknbdppsi.com/]rsxwknbdppsi[/link], http://tpbftnbgarqv.com/

Answer 1

Usually, this kind of behavior can be explained in two ways:

First, it can be a test to discover vulnerabilities of your site, your application or your server. Forms can be really dangerous, they can open the door to your software or your server configuration. Several attacks try to guess whether your system is vulnerable by sending you requests including malicious code or strings.

But in your case, because I can see several [URL= strings, chances are the reason is pure SPAM. This is the typical spam request that is sent to forum, blog and guestbook modules.

In fact, the [URL= string is part of BB code, a common markup language used in blogs and forums used to post URLs. Spammers performs a high number of post request including URLs to generate back-links to their websites or to their clients' websites.

Chances are your contact form has been flagged as a kind of forum or blog.