Threat Level: green Handler on Duty: Jan Kopriva

SANS ISC: A Quick Look at Some Current Comment Spam SANS ISC InfoSec Forums

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A Quick Look at Some Current Comment Spam

As pretty much everybody else allowing comments, our site is getting its fair share of spam. Over the years, we implemented a number of countermeasures, so it is always interesting to see what makes it past these countermeasures. There are a number of recurring themes when it comes to spam:

  • VPN advertisements (we also get A LOT of offers from individuals asking us to post their latest VPN comparison)
  • Outlook file converters. Odd how often they show up.

One recent technique is the use of excerpts from the article as a comment. The intention may be to bypass various spam filters by hitting the right keywords. I was interested to see if I can learn a bit more about how these spam messages are submitted.

The particular comment I looked at advertised a "Wordpress Security Blog". A search of a random text snippet from the site shows about 100 copies of the content indexed by Google. The comment was left earlier today, at 9:38am UTC. The account was actually created about 4 1/2 hrs earlier and used a Protonmail e-mail address. The user agent is plausible:

Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:69.0) Gecko/20100101 Firefox/69.0

This points to Firefox 69 on Windows 7. So this is a current version of Firefox on a bit an older (but still used) version of Windows. The IP address the comment was posted from appears to be located in India, but the email address suggests a Russian user. All hits for this user came from the same IP address.

What's a bit odd: As you sign up for an account to the site, your email needs to be verified. I counted 4 email verification attempts. Only one attempt was made to leave a comment, which of course never got approved.

The weblog entries left by the user match a normal browser. All images, style sheets, fonts, and similar files are loaded. The only odd thing is that the first hit is for a password reset URL. It took about 40 seconds from loading the diary post to leaving a comment, which is about "normal". If this is a script, then it does a good job in delaying its actions to look more real. In some cases, it may be a bit too precise. The spammer also left two comments in our glossary, which were exactly one minute appart (ok. 62 seconds). 

So this looks like a likely at least semi-manual (or "machine-assisted") spam campaign. Here are a couple of things we do to keep spam to a minimum:

  • You need to log in to leave a comment. This is probably the largest deterrent.
  • To set up an account, we verify an email address.
  • we use a stupid simple captcha for the signup process (I find them to work better than standard captchas)
  • New user's comments need to be approved.

With these countermeasures, the spam comments are very manageable. If you ever see that there are "x" comments for a post, but less are visible: This indicates a comment may be waiting to be approved or got marked as spam. Have to fix that counter sometime.

---
Johannes B. Ullrich, Ph.D., Dean of Research, SANS Technology Institute
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I will be teaching next: Defending Web Applications Security Essentials - SANS San Francisco Spring 2020

Johannes

3693 Posts
ISC Handler
> If you ever see that there are "x" comments for a post, but less are visible: This indicates a comment may be waiting to be approved or got marked as spam.

Wouldn't it be simpler for readers if clicking the link from a notification email opened the post in a view that displayed the comments following the post?

Now, after I read the post, if the comment count is not zero, I click to display the post once again, and this time drag the slider down to see if really there are any (approved) comments to read.
Dick Rawson

18 Posts
hm. that may be a simple fix. Let me see if I can add that.
Johannes

3693 Posts
ISC Handler

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