January 3, 2024 at 06:18AM
A new exploitation technique called SMTP smuggling allows threat actors to send malicious emails with fake sender addresses, bypassing security measures. The method exploits vulnerabilities in messaging servers from Microsoft, GMX, and Cisco, impacting SMTP implementations from Postfix and Sendmail. Cisco users are advised to change settings to avoid receiving spoofed emails.
Based on the meeting notes, the key takeaways are:
1. A new exploitation technique called Simple Mail Transfer Protocol (SMTP) smuggling has been identified as a means for threat actors to send spoofed emails with fake sender addresses while bypassing security measures.
2. The technique exploits vulnerabilities in messaging servers from companies such as Microsoft, GMX, and Cisco to send forged emails that appear to be originating from legitimate senders, bypassing security checks like DKIM, DMARC, and SPF.
3. While Microsoft and GMX have addressed the issues, Cisco considers the findings to be a feature rather than a vulnerability and has not changed the default configuration, leaving inbound SMTP smuggling to Cisco Secure Email instances still possible. A recommended fix for Cisco users is to change their settings from “Clean” to “Allow” to avoid receiving spoofed emails with valid DMARC checks.
These clear takeaways summarize the main points discussed in the meeting notes regarding the cyber threat related to SMTP smuggling and email security.