'Smishing' Attack Uses AWS SNS To Impersonate USPS

Security researchers have identified a first-of-its-kind "smishing" attack that uses Amazon Web Services' Simple Notification Service, or SNS.

"Smishing" refers to an attack in which phishing messages are sent in bulk via SMS. This particular attack, which was recently described by researchers at SentinelLabs (which is owned by security firm SentinelOne), sent messages that "often [took] the guise of a message from the United States Postal Service (USPS) regarding a missed package delivery," with the goal of stealing customers' payment card details, addresses and other personally identifiable information.

SentinelLabs identified the culprit as a Python-based script called "SNS Sender." Its success relies on access to compromised AWS SNS credentials from accounts that have opted out of AWS' SNS sandbox security measures. It may be the first such script to do so, based on the researchers' findings.

"SNS Sender is the first script we encountered using AWS SNS to send spam texts," they said in a blog post last week. "While other tools like AlienFox have used business to customer (B2C) communications platforms such as Twilio to conduct SMS spamming attacks, we are unaware of existing research that details tools abusing AWS SNS to conduct such attacks."

The attack only works if the AWS SNS account holder is not using the protected sanbox option. The SNS sandbox, which AWS implements by default, lets users test their SMS messages by first sending them to a limited number of verified recipients. That limit only gets removed after the account holder petitions AWS to move out of the sandbox and into production.

More detailed information about SNS Sender's inner workings is in the SentinelLabs blog. To protect their AWS SNS credentials, the researchers recommend that account holders review AWS' guidance for moving out of the sandbox and "how to change sending limits."

In addition, "Identity and Access Management (IAM) administrators should review identity best practices to optimize their organization's security posture."

About the Author

Gladys Rama (@GladysRama3) is the editorial director of Converge360.


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