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Microsoft warns of a surge in phishing attacks exploiting ...
csoonline.com
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The fault is with how receiving mail servers interpret incoming messages. When MX records lead to complex mail paths, such as on-premises systems or third-party relays before Microsoft 365, standard spoof protection checks like SPF hard-fail and strict DMARC enforcement may not be applied correctly. “In some cases, attackers change the sender name to make the message appear more convincing, while the “From” field is set to a valid internal email address.” Combined with permissive or absent DMARC and SPF policies, these messages may bypass spam filters and land directly in users’ inboxes.
“Internal” routing and weak policies are at fault “When MX records lead to complex mail paths, such as on-premises systems or third-party relays before Microsoft 365, standard spoof protection checks like SPF hard-fail and strict DMARC enforcement may not be applied correctly.” In these cases, a phishing email can arrive with the recipient’s own address in both the “To” and “From” fields, a spoofed message that appears internal at a glance. In some cases, attackers change the sender name to make the message appear more convincing, while the “From” field is set to a valid internal email address.
The fault is with how receiving mail servers interpret incoming messages. When MX records lead to complex mail paths, such as on-premises systems or third-party relays before Microsoft 365, standard spoof protection checks like SPF hard-fail and strict DMARC enforcement may not be applied correctly. “In some cases, attackers change the sender name to make the message appear more convincing, while the “From” field is set to a valid internal email address.” Combined with permissive or absent DMARC and SPF policies, these messages may bypass spam filters and land directly in users’ inboxes.