SMTP:
Exploitation
Guides on relay abuse, spoofed email delivery, and auth brute force
SMTP Credential Attacks
Exploiting SMTP authentication weaknesses via brute force, credential stuffing, and relay abuse to gain unauthorized mail server access.
SMTP exploitation turns a mail server into an attack platform. Open relay abuse lets you send spoofed emails from the target's own domain, bypassing SPF checks for internal phishing. Credential brute-forcing with Hydra or nxc against AUTH LOGIN and AUTH PLAIN can hand you valid mailbox credentials, especially when password policies are weak.
Known CVEs in MTAs like Exim (CVE-2019-10149 for RCE), Haraka (command injection through email headers), and older Postfix/Sendmail builds provide direct remote code execution when the version is right. Shellshock-era SMTP vectors exploited bash through mail delivery scripts. Always check the MTA version from enumeration against public exploit databases.
Successful exploitation here gives you email access for credential harvesting, a relay for further phishing, or a full shell on the mail server itself.