Web Scanning Sonicwall for CVE-2021-20016
There was a post initially published in January 2022 showing an exploitable "probable zero-day vulnerabilities"[1] for Sonicwall but looking back in what has been submitted in the past year to ISC, this past week was the first time we have been getting some reports. The activity occured on the 23 April 2025 between 18:00 - 19:00 UTC but since then based on activity reported to DShield (see graphs below) has been happening almost daily:
The DShield sensors (2) captured a significant probe for 3 URL from IPs 45.227.255.93 141.98.80.125. The 3 URLs are as follows:
Path Scanned
A review of the data submitted to DShield shows this activity for the first time on the 22 April 2023
/__api__/v1/config/domains [3]
/__api__/v1/logon [4]
Indicator
45.227.255.89
45.227.255.93
141.98.80.125
141.98.80.146
[1] https://es-la.tenable.com/blog/cve-2021-20016-zero-day-vulnerability-in-sonicwall-secure-mobile-access-sma-exploited
[2] https://cow-prod-www-v3.azurewebsites.net/publications/security-advisories/2021-006/pdf
[3] https://isc.sans.edu/weblogs/urlhistory.html?url=L19fYXBpX18vdjEvY29uZmlnL2RvbWFpbnM=
[4] https://isc.sans.edu/weblogs/urlhistory.html?url=L19fYXBpX18vdjEvbG9nb24=
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Guy Bruneau IPSS Inc.
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Twitter: GuyBruneau
gbruneau at isc dot sans dot edu
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