I am getting dozens of 404 errors on my site that are requests for gif's with apparently random names, like 4273uaqa.gif and 5pwowlag.gif.

I see that most of them are coming from one user. I assume something is happening in the background on her machine without her knowledge -- a malware thing on the client.

Have you seen this behavior before, and do you know what sort of malware might cause it?

Would love to advise my customer that s/he has an issue. I'd also like to stop getting these 404 reports.

(reposted from main Stack Overflow)