Summary:
Millions of nearly undetectable phishing emails impersonating well-known companies spread daily in the first half of 2024 due to certain features in Microsoft 365 and Proofpoint's email protection service. Proofpoint's secure email gateway (SEG) acts as a firewall for corporate emails, filtering incoming messages and authenticating outgoing ones. However, researchers from Guardio discovered a campaign exploiting a "super-permissive misconfiguration flaw" to send scam emails that appeared to come from legitimate corporate accounts.


Jeremy Fuchs from Check Point Software explained that the basic infrastructure of email has not changed much, making it relatively easy to spoof sender addresses. In the EchoSpoofing campaign, attackers used their own SMTP server to send emails with forged "From" headers, appearing to come from major corporations like Disney and IBM. Proofpoint's SEG had a setting that trusted any emails routed through Microsoft Office 365, which is widely used among businesses. Attackers took advantage of this by sending emails through Microsoft 365 to known Proofpoint customers, who would then unknowingly receive these malicious emails as legitimate ones.


Security Officer Comments:
The EchoSpoofing campaign began in January and was first discovered by Proofpoint in late March. Despite initial remediation efforts, the forged emails continued to increase, averaging three million per week and occasionally surpassing ten million. The attackers demonstrated keen operational awareness by switching domains and Office365 accounts to stay under the radar.

EchoSpoofing seems to have diminished recently after Proofpoint introduced a vendor-specific header for outgoing emails, allowing customers to restrict the 365 accounts allowed to send emails on their behalf. However, despite Proofpoint's efforts to alert Microsoft, the attackers' malicious Office365 accounts remained active months later. This incident highlights the need for organizations to implement secure email controls like DMARC monitoring to prevent such attacks and underscores the importance of diligent email security practices to protect against more sophisticated threats.


Suggested Corrections:

IOCs:
https://labs.guard.io/echospoofing-...nts-email-protection-to-dispatch-3dd6b5417db6


Users should always be cautious of individuals or organizations that ask for personal information. Most companies will not ask for sensitive data from its customers. If in doubt, users should verify with the company itself to avoid any potential issues.


Users should always take a close look at the sender’s display name when checking the legitimacy of an email. Most companies use a single domain for their URLs and emails, so a message that originates from a different domain is a red flag.


As a general rule, users should not click links or download files even if they come from seemingly “trustworthy” sources.


Check for mismatched URLs. While an embedded URL might seem perfectly valid, hovering above it might show a different web address. In fact, users should avoid clicking links in emails unless they are certain that it is a legitimate link.


Users should always be on the lookout for any grammatical errors and spelling mistakes. Legitimate companies will often employ proofreaders and editors who ensure that the materials they send out are error-free.


Users should not be frightened or intimidated by messages that have an alarmist tone. They should double check with the company if they are uncertain about the status of their accounts.


Phishing emails are designed to be sent to a large number of people, so they need to be as impersonal as possible. Users should check whether the message contains a generic subject and greeting, as this can be a sign of a phishing attempt.


Although not every end user has access to advanced anti-phishing software, they can still use the built-in protection of their email clients to filter messages. One example is setting the email client to block all images unless approved.


Legitimate companies will never send confirmation emails unless there are specific reasons for doing so. In fact, most companies will avoid sending unsolicited messages unless it’s for company updates, newsletters, or advertising purposes.


Users should always take the context of an email or message into account. For example, most online accounts do away with viewable member numbers, so users should be wary if they receive emails containing a “member number” for services that generally don’t use them.


It is important to take note of unusual information in the text of the message. Any mentions of operating systems and software that are not typically used by consumers can often be indicators of a phishing attempt.


If it seems suspicious, it probably is. Users should always err on the side of caution when it comes to sending out personally identifiable information through messages and emails.


Link(s):
https://www.darkreading.com/cloud-security/disney-nike-ibm-signatures-3m-fake-emails https://labs.guard.io/echospoofing-...nts-email-protection-to-dispatch-3dd6b5417db6