Can Comment Spam Be Stopped?

By Larry Seltzer  |  Posted 2005-01-20 Print this article Print

Opinion: "Nofollow" is not a comment-spam killer, but it should help—although perhaps not as much as some other solutions.

I didnt need to learn about comment spam by reading Ive gotten waves of it in my own blogs comments. You may have noticed that you now have to fill in one of those challenge entries asking you to type in the text portrayed in a nearby graphic (a "captcha"), and this has largely stopped the spammers. Now Google, MSN, Yahoo and Six Apart have gotten together to propose an interesting change to their practices aimed at fighting comment spam. They will not index links that contain rel=nofollow in the anchor tag. Here are the links to the announcements by Google, MSN and Yahoo.

The motivation for comment spam has never been to get people to click on the links, but rather to get search engines that scan the blogs to scan and follow the links. As the famous Dave Winer says, "Comment spammers want the PageRank."

One price that is paid for this is that blog software writers need to modify their software to include rel=nofollow in the links. This has already begun with Movable Type. The second price paid is that legitimate links wont get followed either. Perhaps more sophisticated versions of blog software could allow some users to include links without rel=nofollow. Anyway, losing the indexing of such links seems a small prices to pay if nofollow helps, which I expect it will.

But we already know that spammers will go ahead and spam dead e-mail addresses and perform other useless endeavors because the cost of doing so is near-zero, and its probably easier for them to keep the waste in their systems than to spend the time cleaning out their address databases. So, unless the whole blogosphere adopts nofollow, nofollow-enabled blogs can expect to get more comment spam. They will need to adopt other techniques.

Heres an interesting one, and you might have seen it message boards elsewhere: Require a delay, maybe 10 seconds, between the time the user views a message and the time they post a response to it. The idea is that posting comment spam will become too expensive in terms of time. I wonder whether this would stop a clever spammer. Unlike the Penny Black project, which attempts to use time delays to make e-mail spam expensive by requiring the sender to perform some work and proof of it, a simple delay allows the spammer to put the spamming thread to sleep. In other words, have the program pause for the required delay, and have multiple spamming threads run at once.

Once the spammer is multithreading, other defenses become possible, such as flood detection, blacklists and keyphrase blocking. And if youre using WordPress, you can use Spam Karma, a plug-in that runs a series of tests on every comment.

Sounds like an arms race. Distasteful. And even if comment spam in its current form were disincentivized out of existence, spammers would find some new way to abuse blogs. Some people cant see something good without finding a way to ruin it. They wont go down easily.

Check out eWEEK.coms for the latest security news, reviews and analysis. And for insights on security coverage around the Web, take a look at Security Center Editor Larry Seltzers Weblog. More from Larry Seltzer
Larry Seltzer has been writing software for and English about computers ever since—,much to his own amazement—,he graduated from the University of Pennsylvania in 1983.

He was one of the authors of NPL and NPL-R, fourth-generation languages for microcomputers by the now-defunct DeskTop Software Corporation. (Larry is sad to find absolutely no hits on any of these +products on Google.) His work at Desktop Software included programming the UCSD p-System, a virtual machine-based operating system with portable binaries that pre-dated Java by more than 10 years.

For several years, he wrote corporate software for Mathematica Policy Research (they're still in business!) and Chase Econometrics (not so lucky) before being forcibly thrown into the consulting market. He bummed around the Philadelphia consulting and contract-programming scenes for a year or two before taking a job at NSTL (National Software Testing Labs) developing product tests and managing contract testing for the computer industry, governments and publication.

In 1991 Larry moved to Massachusetts to become Technical Director of PC Week Labs (now eWeek Labs). He moved within Ziff Davis to New York in 1994 to run testing at Windows Sources. In 1995, he became Technical Director for Internet product testing at PC Magazine and stayed there till 1998.

Since then, he has been writing for numerous other publications, including Fortune Small Business, Windows 2000 Magazine (now Windows and .NET Magazine), ZDNet and Sam Whitmore's Media Survey.

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