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Port Intelligence Profile

Port 143: IMAP

Analyze default service protocols, historical security vulnerabilities, hardening methods, and firewall rules for port 143.

Default Service
IMAP
Protocol
TCP
Risk Level
Medium
Port Range
System (1-1023)

1. Port Purpose & Usage

Internet Message Access Protocol (IMAP) is a standard protocol used by email clients to retrieve messages from a mail server. Unlike POP3, IMAP leaves mail on the server, permitting access from multiple devices.

Common Service Implementations

Dovecot

A secure, high-performance IMAP and POP3 server for Linux systems.

Courier-IMAP

Fast, secure IMAP mail server.

2. Security Risks & Vulnerability Profiles

IMAP traffic on port 143 is unencrypted by default. Mailboxes, folders, and access credentials can be harvested by attackers on the network path.

Historical CVE References

CVE-2019-11500

Dovecot Buffer Overflow. An issue in the IMAP login process allowed authenticated users to trigger memory corruption and execute arbitrary code.

3. Hardening & Mitigation Checklist

1
Disable port 143 and force IMAPS (IMAP over SSL/TLS) on port 993.
2
Enforce strong authentication policies and limit connection counts per host IP.

4. Firewall Command Examples

Use the following system configurations to restrict open port exposure on Linux hosts:

# UFW: Deny public IMAP access ufw deny 143/tcp
# iptables: Drop all incoming TCP packets on port 143 iptables -A INPUT -p tcp --dport 143 -j DROP

Further Analysis

Email Infrastructure Ports

Ports often operate in clusters. When analyzing a service on Port 143, security engineers typically check the status of these related ports.