detecting-lateral-movement-with-zeek

name	detecting-lateral-movement-with-zeek
description	Detect lateral movement in network traffic using Zeek (formerly Bro) log analysis. Parses conn.log, smb_mapping.log, smb_files.log, dce_rpc.log, kerberos.log, and ntlm.log to identify SMB file transfers, NTLM account spray activity, remote service execution, and anomalous internal connections. . Use when working with detecting lateral movement with zeek.
domain	cybersecurity
tags	["zeek","lateral-movement","smb","dce-rpc","ntlm-spray","network-forensics"]
subdomain	network-security
version	1.0
author	oyi77
license	Apache-2.0
nist_csf	["PR.IR-01","DE.CM-01","ID.AM-03","PR.DS-02"]

Detecting Lateral Movement With Zeek

Overview

Cybersecurity skill for detecting lateral movement with zeek. Follows industry best practices and security standards.

When to Use

Trigger phrases:

• "detecting lateral movement with zeek"

• "Detect lateral movement in network traffic using Zeek (formerly Bro) log analysi"

• Hunting for lateral movement after an initial compromise indicator is found on one endpoint

• Investigating suspected NTLM account spray or Pass-the-Ticket attacks across the internal network

• Monitoring SMB traffic for unauthorized file transfers to admin shares (C$, ADMIN$, IPC$)

• Detecting remote service execution via DCE/RPC (PsExec, schtasks, WMI lateral patterns)

• Building alerting rules for internal network anomalies in a Zeek-based NSMP deployment

• Performing post-incident timeline reconstruction using Zeek logs as a network-level evidence source

Do not use as a standalone detection mechanism. Zeek sees network traffic only; combine with endpoint telemetry (Sysmon, EDR) for full visibility. Encrypted SMB3 traffic may limit Zeek's visibility into file-level details.

When NOT to Use

• When you lack proper authorization for testing
• For production systems without change management
• When the task requires legal or compliance expertise beyond technical scope

Prerequisites

• Zeek 6.0+ deployed on a network tap or SPAN port monitoring internal VLAN traffic
• Zeek SMB analyzer enabled (loaded by default: @load base/protocols/smb)
• Zeek DCE/RPC analyzer enabled (@load base/protocols/dce-rpc)
• Zeek Kerberos analyzer enabled (@load base/protocols/krb)
• Python 3.8+ (standard library only)
• Access to Zeek log directory (default: /opt/zeek/logs/current/)
• Familiarity with Zeek TSV log format (fields separated by \t, header lines prefixed with #)

Workflow

# Example: IOC detection
import re

IOC_PATTERNS = {
    "ip": r"\b(?:\d{1,3}\.){3}\d{1,3}\b",
    "domain": ,
    : ,
    : ,
}

 () -> :
     {k: re.findall(v, text)  k, v  IOC_PATTERNS.items()}