Table of contents
Security Detections
After loading a capture the analyzer runs a set of heuristic detections. Their results appear in the Security tab and in every report. Each finding has a severity, a description, the source and target, when it happened, the evidence, a recommendation, and a display filter that selects the evidence packets.
Detections are heuristics. Treat a finding as a lead to verify, not as proof: an authorised vulnerability scanner also triggers "port scan".
What is detected
| Finding | Severity | Triggered when |
|---|---|---|
| TCP port scan | High | one host sends SYNs to many different ports of another host (default 25+) |
| Network sweep | Medium | one host sends SYNs to the same port on many hosts (default 15+) |
| ICMP ping sweep | Medium | echo requests to many different addresses (default 15+) |
| SYN flood | High | many handshakes to one service never complete (default 200+, mostly failed) |
| ARP spoofing | High | one IP address is announced by more than one MAC address |
| Several DHCP servers | High | DHCP offers/ACKs come from more than one server |
| ICMP redirect | Medium | ICMP redirect messages are seen |
| Credentials in clear text | High | logins over FTP, Telnet, POP3, IMAP, SMTP AUTH PLAIN or HTTP Basic authentication |
| Unencrypted protocol in use | Low | established Telnet, FTP, TFTP, POP3, IMAP, rlogin or rsh sessions |
| DNS tunnelling | High | a client sends many queries with very long or random-looking labels under one domain |
| Many failed DNS lookups | Medium | a client receives many NXDOMAIN answers (DGA malware, misconfiguration) |
| Beaconing | Medium | repeated connections to the same Internet endpoint at a regular interval (low jitter) |
| Large upload | Medium | an internal host sends a lot of data to an external host (default 5 MB) |
| Outdated TLS | Medium | SSL 3.0 / TLS 1.0 / TLS 1.1 negotiated, or a weak cipher (RC4, 3DES, NULL, EXPORT) |
| Suspicious port | Medium | a connection to a port typical of backdoors or botnets (4444, 31337, 6667, ...) |
| Form data over HTTP | Low | a POST/PUT to an external server over plain HTTP |
Captured passwords are masked (W*********!) unless masking is disabled in the settings or
with --no-mask on the command line.
Tuning
Analysis → Detection Settings changes the thresholds (ports for a scan, hosts for a sweep, failed handshakes for a flood, query count and label length for DNS tunnelling, beaconing interval and jitter, upload size...). The capture is re-analysed immediately. Restore Defaults resets them.
Internal and external addresses
Private (RFC 1918), CGNAT, link-local, loopback and IPv6 ULA / link-local addresses count as internal; everything else as external. Beaconing and large-upload detections only consider traffic to external hosts.
