STARTTLS
An extension mechanism in the SMTP protocol that upgrades a session from plaintext to TLS encryption. It begins in plaintext and then negotiates the upgrade, which introduces a risk of downgrade attacks.
Timeline (last 90 days)
STARTTLS initiates an upgrade request within an SMTP session to switch a plaintext connection to a TLS encrypted channel, rather than encrypting as soon as the connection is established.
STARTTLS carries a downgrade attack risk: an attacker can intercept the upgrade request and force both parties back to plaintext communication, often without the user noticing at all.
STARTTLS has an opportunistic encryption problem: a man-in-the-middle stripping the STARTTLS directive causes communication to silently downgrade to plaintext transmission.
All Facts (3)
STARTTLS initiates an upgrade request within an SMTP session to switch a plaintext connection to a TLS encrypted channel, rather than encrypting as soon as the connection is established.
50%UnverifiedSTARTTLS carries a downgrade attack risk: an attacker can intercept the upgrade request and force both parties back to plaintext communication, often without the user noticing at all.
50%UnverifiedSTARTTLS has an opportunistic encryption problem: a man-in-the-middle stripping the STARTTLS directive causes communication to silently downgrade to plaintext transmission.
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