UDP Monitoring

Port 514 (Syslog)

Learn about port 514 (Syslog) - security risks, vulnerabilities, and common uses. Find devices with port 514 open.

Quick Info

Port Number

514

Protocol

UDP

Service

Syslog

IANA Name

Syslog

Service Description

Network port 514 (UDP) is predominantly known for its use by the Syslog protocol. Syslog is a standard protocol for message logging. It allows networked devices to send event notifications across IP networks to event message collectors. This enables centralized logging, which is crucial for security auditing, system debugging, and general system monitoring. The protocol itself is relatively simple: a device generates a log message, formats it according to the Syslog standard (which includes priority, facility, hostname, and message content), and sends it via UDP to a designated Syslog server listening on port 514. The server then processes and stores these messages for later analysis. The simplicity of Syslog and its widespread adoption have made it a cornerstone of network management.

Originally developed in the 1980s, Syslog's initial implementations lacked robust security features. The reliance on UDP, a connectionless protocol, means that messages are not guaranteed to be delivered, nor is their origin authenticated. The inherent trust relationship, where the Syslog server assumes the authenticity of the sender, makes it vulnerable to spoofing and data injection attacks. Modern implementations often use TCP for increased reliability and TLS for encryption and authentication, addressing some of these original shortcomings. However, UDP port 514 remains a common target for reconnaissance and exploitation, especially in legacy systems where security updates are lacking or non-existent.

## Firewall Recommendations

When deciding whether to allow or block UDP port 514, consider the following: If you are using Syslog for centralized logging, you will need to allow inbound traffic on this port from your network devices. However, it is strongly recommended to restrict access to this port to only trusted IP addresses or networks. If Syslog is not in use, blocking this port is the most secure option. For improved security, consider using TCP with TLS encryption (TCP port 6514) instead of UDP. Implement rate limiting to mitigate DoS attacks, and regularly monitor logs for suspicious activity. Ensure that your Syslog server and client software are up-to-date with the latest security patches.

Security Information

UDP port 514 is inherently susceptible to several security risks due to the lack of authentication and encryption in its basic form. A primary concern is IP address spoofing, where an attacker can forge the source IP address of a Syslog message to inject malicious log entries. These entries can be used to mask real attacks, flood the logging system, or even manipulate reports generated from the logs. Another risk is denial-of-service (DoS) attacks, where an attacker floods the server with Syslog messages, overwhelming its resources and preventing it from processing legitimate logs. Because UDP is connectionless, it's easier for attackers to generate a large volume of fake messages. Furthermore, the unencrypted nature of the standard UDP-based Syslog means that sensitive information contained within log messages can be intercepted by eavesdroppers. Attackers often target this port to gather reconnaissance information about the network, identify vulnerabilities, or compromise systems.

Known Vulnerabilities

CVE	Name	Severity	Description
CVE-2019-14900	rsyslog: Crafted messages can crash rsyslogd	Medium	rsyslogd can crash if it receives a specially crafted message, leading to a denial of service.
CVE-2017-16809	syslog-ng: Heap-based buffer overflow in IPv6 parsing	High	A heap-based buffer overflow vulnerability exists in syslog-ng when parsing IPv6 addresses in log messages, potentially allowing for arbitrary code execution.
CVE-2013-2065	rsyslog: Input Validation Vulnerability	Medium	rsyslog contains an input validation vulnerability in the imuxsock module which may allow an attacker to execute arbitrary code.
CVE-2008-0640	syslog-ng: Format String Vulnerability	High	syslog-ng contains a format string vulnerability that allows remote attackers to execute arbitrary code.
CVE-2021-44228	Log4Shell	Critical	Although technically a vulnerability in the Log4j library, it heavily impacts applications that use Log4j to process Syslog messages, allowing remote code execution via crafted log entries.