How do I verify that SNS messages sent to HTTP and HTTPS endpoints are authentic?

Resolution

It's a best practice to use certificate-based signature validation when you verify the authenticity of an Amazon SNS notification. For more information, see Verifying the signatures of Amazon SNS messages.

To help prevent spoofing attacks when you verify Amazon SNS message signatures, complete the following actions:

• Always use HTTPS to get the certificate from Amazon SNS.
• Validate the authenticity of the certificate.
• Verify that Amazon SNS sent the certificate.
• Use one of the supported AWS SDKs for Amazon SNS to validate and verify messages when possible.

Example message body

The following is an example message payload string sent from Amazon SNS:

{"Type" : "Notification",
"MessageId" : "e1f2a232-e8ce-5f0a-b5d3-fbebXXXXXXXX",
"TopicArn" : "arn:aws:sns:us-east-1:XXXXXXXX:SNSHTTPSTEST",
"Subject" : "Test",
"Message" : "TestHTTPS",
"Timestamp" : "2021-10-07T18:55:19.793Z",
"SignatureVersion" : "1",
"Signature" : "VetoDxbYMh0Ii/87swLEGZt6FB0ZzGRjlW5BiVmKK1OLiV8B8NaVlADa6ThbWd1s89A4WX1WQwJMayucR8oYzEcWEH6//VxXCMQxWD80rG/NrxLeoyas4IHXhneiqBglLXh/R9nDZcMAmjPETOW61N8AnLh7nQ27O8Z+HCwY1wjxiShwElH5/+2cZvwCoD+oka3Gweu2tQyZAA9ergdJmXA9ukVnfieEEinhb8wuaemihvKLwGOTVoW/9IRMnixrDsOYOzFt+PXYuKQ6KGXpzV8U/fuJDsWiFa/lPHWw9pqfeA8lqUJwrgdbBS9vjOJIL+u2c49kzlei8zCelK3n7w==",
"SigningCertURL" : "https://sns.us-east-1.amazonaws.com/SimpleNotificationService-7ff5318490ec183fbaddaa2aXXXXXXXX.pem",
"UnsubscribeURL" : "https://sns.us-east-1.amazonaws.com/?Action=Unsubscribe&SubscriptionArn=arn:aws:sns:us-east-1:XXXXXXXX:SNSHTTPSTEST:b5ab2db8-7775-4852-bd1a-2520XXXXXXXX",
"MessageAttributes" : {
"surname" : {"Type":"String","Value":"SNSHTTPSTest"}
}
}

For more information, see Parsing Amazon SNS message formats.

Related information

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