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Phishing via "com-" prefix domains

Published: 2025-02-05. Last Updated: 2025-02-05 17:50:33 UTC
by Johannes Ullrich (Version: 1)
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Phishing is always a "whack the mole" like game. Attackers come up with new ways to fool victims. Security tools are often a step behind. Messages claiming to collect unpaid tolls are one current common theme among phishing (smishing?) messages. I just received another one today:

Screenshot of a smishing message claiming to alert the recipient of unpaid tolls

The FBI's Internet Crime Complaint Center warned of these types of messages last April [1]. The message was pretty easily identified as fraud by the "From" number, a phone number in the Phillipines. But I found the domain clever.

Florida's toll system is commonly referred to as "Sunpass", and the legitimate website is sunpass.com. The scammer attempted to emulate this name by using a domain that starts with "com-". An unsuspecting user may consider this a valid sunpass.com address.

So I looked at our "newly registered domains" data to see how many "com-*" domains we have, and this prefix looks indeed popular, usually followed by a few random characters:

Here are a few example:

com-typopn.top
com-tyuiop.top
com-uilqsc.top
com-vfgbnj.top
com-wsxder.top
com-xyuoph.top
com-ywbl.top
com-yzgv.top
com-zfrulb.top pish

Looking at the Top 10 TLDs used for these domains, the usual "dirty" gTLDs like "top" and "XYZ" stick out, but "com", "info" and "us" are also included:

TLD Count
top 16,606
com 12,293
xyz 3005
info 2731
cfd 2413
vip 2217
sbs 1461
xin 1453
us 1245
online 1140

The registrations vary over time, but as of November last year, the registrations have increased somewhat.

Overall, it is likely worthwhile to add a query to your DNS logs to review lookups for these domains. I found 10% of the domains from the last few days in Phishtank. Many of the remaining were confirmed malicious as well. Luckily, many appear to have already been taken down. However, I have not spotted a valid side among the last 1,000 registered domains.

[1] https://www.ic3.gov/PSA/2024/PSA240412

 

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Johannes B. Ullrich, Ph.D. , Dean of Research, SANS.edu
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