What it does. 'Detects early-stage ransomware indicators in network traffic before Part of mukul975/Anthropic-Cybersecurity-Skills (817 security skills) (mukul975/Anthropic-Cybersecurity-Skills).

Upstream	mukul975/Anthropic-Cybersecurity-Skills
Skill file	skills/detecting-ransomware-precursors-in-network/SKILL.md
License	Apache-2.0 (skill folder LICENSE)
Author	mukul975
Fetched	2026-09-10

Install

• npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill detecting-ransomware-precursors-in-network, or copy the skill folder into ~/.claude/skills/detecting-ransomware-precursors-in-network/.
• Raw file: curl -sL https://raw.githubusercontent.com/mukul975/Anthropic-Cybersecurity-Skills/HEAD/skills/detecting-ransomware-precursors-in-network/SKILL.md

SKILL.md (verbatim)

name: detecting-ransomware-precursors-in-network
description: 'Detects early-stage ransomware indicators in network traffic before
  encryption begins, including initial access broker activity, command-and-control
  beaconing, credential harvesting, reconnaissance scanning, and staging behavior.
  Uses network detection tools (Zeek, Suricata, Arkime), SIEM correlation rules, and
  threat intelligence feeds to identify ransomware precursor patterns such as Cobalt
  Strike beacons, Mimikatz network signatures, and RDP brute-force attempts. Activates
  for requests involving pre-ransomware detection, network-based ransomware indicators,
  or early warning ransomware monitoring.

  '
domain: cybersecurity
subdomain: ransomware-defense
tags:
- ransomware
- detection
- network-security
- incident-response
- defense
version: 1.0.0
author: mahipal
license: Apache-2.0
nist_csf:
- PR.DS-11
- RS.MA-01
- RC.RP-01
- PR.IR-01
mitre_attack:
- T1078
- T1190
- T1059
- T1003
- T1110
mitre_f3:
  version: '1.1'
  tactics:
  - initial-access
  - positioning
  - monetization
  techniques:
  - id: T1110
    name: Brute Force
    tactic: initial-access
    source: attack
  - id: T1219
    name: Remote Access Tools
    tactic: positioning
    source: attack
  - id: T1650
    name: Acquire Access
    tactic: resource-development
    source: attack
  - id: F1018
    name: Convert to Cryptocurrency
    tactic: monetization
    source: f3

Detecting Ransomware Precursors in Network Traffic

When to Use

• Building detection rules for pre-ransomware network activity (the average time from Cobalt Strike deployment to encryption is 17 minutes)
• Monitoring for initial access broker (IAB) indicators that precede ransomware deployment
• Creating SIEM correlation rules that chain multiple precursor events into high-confidence alerts
• Tuning network detection systems to distinguish ransomware staging from normal administrative activity
• Investigating suspicious network patterns that may indicate ransomware operators have established a foothold

Do not use for post-encryption response (see recovering-from-ransomware-attack). This skill focuses on the pre-encryption detection window where containment can prevent data loss.

Prerequisites

• Network detection platform (Zeek/Bro, Suricata, or Arkime/Moloch) deployed on network TAP or SPAN ports
• SIEM platform (Splunk, Elastic Security, Microsoft Sentinel, or QRadar) ingesting network logs
• Threat intelligence feeds covering ransomware IOCs (CISA, abuse.ch, OTX, MISP)
• Network flow data (NetFlow/IPFIX) from core routers and firewalls
• DNS query logging from internal resolvers
• Full packet capture capability for incident investigation

Workflow

Step 1: Identify Ransomware Kill Chain Phases in Network Traffic

Map network-observable indicators to each pre-encryption phase:

Kill Chain Phase	Network Indicators	Detection Source
Initial Access	RDP brute force, VPN credential stuffing, phishing callback	Firewall logs, IDS, proxy logs
C2 Establishment	Cobalt Strike beacons (HTTPS/DNS), Sliver/Brute Ratel callbacks	Zeek SSL/HTTP logs, DNS logs
Credential Harvesting	NTLM relay, Kerberoasting, DCSync traffic	Zeek Kerberos/NTLM logs, DC logs
Reconnaissance	Internal port scanning, AD enumeration (LDAP/SMB)	Zeek conn.log, flow data
Lateral Movement	PsExec/WMI/WinRM traffic, RDP pivoting, SMB file copies	Zeek SMB/DCE-RPC logs
Staging	Data aggregation, archive creation, cloud upload prep	Proxy logs, DNS logs, DLP

Step 2: Deploy Network Detection Rules

Suricata rules for common ransomware precursors:

# Cobalt Strike default HTTPS beacon profile detection
alert tls $HOME_NET any -> $EXTERNAL_NET any (msg:"RANSOMWARE PRECURSOR - Cobalt Strike Default TLS Certificate"; tls.cert_subject; content:"Major Cobalt Strike"; sid:3000001; rev:1;)

# Cobalt Strike DNS beacon
alert dns $HOME_NET any -> any 53 (msg:"RANSOMWARE PRECURSOR - Cobalt Strike DNS Beacon Pattern"; dns.query; pcre:"/^[a-z0-9]{3}\.[a-z]{4,8}\./"; threshold:type both, track by_src, count 50, seconds 60; sid:3000002; rev:1;)

# Mimikatz network signature (DCSync - DRS GetNCChanges)
alert tcp $HOME_NET any -> $HOME_NET 135 (msg:"RANSOMWARE PRECURSOR - Possible DCSync/Mimikatz"; content:"|05 00 0b|"; offset:0; depth:3; content:"|e3 51 4d 2b 4b 47 15 d2|"; sid:3000003; rev:1;)

# Internal network scanning (many connections, few bytes)
alert tcp $HOME_NET any -> $HOME_NET any (msg:"RANSOMWARE PRECURSOR - Internal Port Scan"; flags:S; threshold:type both, track by_src, count 100, seconds 10; sid:3000004; rev:1;)

# PsExec service installation over SMB
alert tcp $HOME_NET any -> $HOME_NET 445 (msg:"RANSOMWARE PRECURSOR - PsExec Service Install"; content:"|ff|SMB"; content:"PSEXESVC"; nocase; sid:3000005; rev:1;)

# RDP brute force from internal host (lateral movement)
alert tcp $HOME_NET any -> $HOME_NET 3389 (msg:"RANSOMWARE PRECURSOR - Internal RDP Brute Force"; flow:to_server,established; threshold:type both, track by_src, count 20, seconds 60; sid:3000006; rev:1;)

# Large SMB file transfer (data staging)
alert tcp $HOME_NET any -> $HOME_NET 445 (msg:"RANSOMWARE PRECURSOR - Large SMB Transfer Possible Staging"; flow:to_server,established; dsize:>60000; threshold:type both, track by_src, count 100, seconds 300; sid:3000007; rev:1;)

Zeek scripts for behavioral detection:

# detect_ransomware_precursors.zeek
# Detect high volume of failed SMB connections (credential testing)

@load base/protocols/smb

module RansomwarePrecursor;

export {
    redef enum Notice::Type += {
        SMB_Brute_Force,
        Suspicious_Internal_Scan,
        Excessive_DNS_Queries,
        SMB_Admin_Share_Access,
    };

    const smb_fail_threshold = 10 &redef;
    const scan_threshold = 50 &redef;
    const dns_query_threshold = 200 &redef;
}

global smb_fail_count: table[addr] of count &default=0 &create_expire=5min;
global conn_count: table[addr] of set[addr] &create_expire=1min;

event smb2_message(c: connection, hdr: SMB2::Header, is_orig: bool) {
    if (hdr$status != 0) {
        ++smb_fail_count[c$id$orig_h];
        if (smb_fail_count[c$id$orig_h] >= smb_fail_threshold) {
            NOTICE([$note=SMB_Brute_Force,
                    $msg=fmt("Host %s has %d failed SMB attempts", c$id$orig_h, smb_fail_count[c$id$orig_h]),
                    $src=c$id$orig_h,
                    $identifier=cat(c$id$orig_h)]);
        }
    }
}

event new_connection(c: connection) {
    if (c$id$orig_h in Site::local_nets && c$id$resp_h in Site::local_nets) {
        if (c$id$orig_h !in conn_count)
            conn_count[c$id$orig_h] = set();
        add conn_count[c$id$orig_h][c$id$resp_h];
        if (|conn_count[c$id$orig_h]| >= scan_threshold) {
            NOTICE([$note=Suspicious_Internal_Scan,
                    $msg=fmt("Host %s connected to %d internal hosts in 1 min", c$id$orig_h, |conn_count[c$id$orig_h]|),
                    $src=c$id$orig_h,
                    $identifier=cat(c$id$orig_h)]);
        }
    }
}

Step 3: Create SIEM Correlation Rules

Splunk correlation for ransomware precursor chain:

| tstats count FROM datamodel=Network_Traffic
  WHERE earliest=-24h All_Traffic.dest_port IN (445, 135, 139, 3389, 5985, 5986)
    AND All_Traffic.src_ip IN 10.0.0.0/8
    AND All_Traffic.dest_ip IN 10.0.0.0/8
  BY All_Traffic.src_ip, All_Traffic.dest_port, _time span=1h
| stats dc(All_Traffic.dest_port) as port_count,
        values(All_Traffic.dest_port) as ports,
        count as total_conns
  BY All_Traffic.src_ip
| where port_count >= 3 AND total_conns > 50
| rename All_Traffic.src_ip as src_ip
| lookup threat_intel_ioc ip as src_ip OUTPUT threat_type
| eval risk_score = case(
    port_count >= 5 AND total_conns > 200, "CRITICAL",
    port_count >= 3 AND total_conns > 50, "HIGH",
    1=1, "MEDIUM")
| table src_ip, ports, port_count, total_conns, risk_score, threat_type

Microsoft Sentinel KQL - Ransomware precursor correlation:

let timeframe = 24h;
let RDPBruteForce = SecurityEvent
| where TimeGenerated > ago(timeframe)
| where EventID == 4625
| where LogonType == 10
| summarize FailedRDP = count() by TargetAccount, IpAddress, bin(TimeGenerated, 1h)
| where FailedRDP > 10;
let SuspiciousSMB = SecurityEvent
| where TimeGenerated > ago(timeframe)
| where EventID == 5145
| where ShareName has "ADMIN$" or ShareName has "C$" or ShareName has "IPC$"
| summarize AdminShareAccess = count() by SubjectUserName, IpAddress, bin(TimeGenerated, 1h)
| where AdminShareAccess > 5;
let ServiceInstalls = SecurityEvent
| where TimeGenerated > ago(timeframe)
| where EventID == 7045
| where ServiceName has_any ("PSEXESVC", "meterpreter", "beacon");
RDPBruteForce
| join kind=inner SuspiciousSMB on IpAddress
| project TimeGenerated, IpAddress, TargetAccount, FailedRDP, SubjectUserName, AdminShareAccess
| extend AlertTitle = "Ransomware Precursor: RDP Brute Force + Admin Share Access"

Step 4: Integrate Threat Intelligence

Configure automated IOC feeds for known ransomware infrastructure:

# Download and update ransomware C2 blocklists
# abuse.ch Feodo Tracker (Cobalt Strike, TrickBot, BazarLoader C2s)
curl -s https://feodotracker.abuse.ch/downloads/ipblocklist.csv | \
  grep -v "^#" | cut -d, -f2 > /opt/threat-intel/feodo_ips.txt

# abuse.ch URLhaus (malware distribution URLs)
curl -s https://urlhaus.abuse.ch/downloads/csv_recent/ | \
  grep -v "^#" | cut -d, -f3 > /opt/threat-intel/urlhaus_urls.txt

# abuse.ch ThreatFox (ransomware IOCs)
curl -s https://threatfox.abuse.ch/export/csv/recent/ | \
  grep -i "ransomware" | cut -d, -f3 > /opt/threat-intel/ransomware_iocs.txt

# CISA Known Exploited Vulnerabilities (initial access vectors)
curl -s https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json | \
  python3 -c "import json,sys; data=json.load(sys.stdin); [print(v['cveID'],v['vendorProject'],v['product']) for v in data['vulnerabilities'] if 'ransomware' in v.get('knownRansomwareCampaignUse','').lower()]"

Step 5: Establish Alert Triage and Escalation

Define triage procedures based on precursor confidence level:

Alert Type	Confidence	Response Time	Action
Confirmed Cobalt Strike beacon	High	15 minutes	Isolate host immediately, trigger IR
DCSync/Kerberoasting from non-DC	High	15 minutes	Disable account, isolate host, trigger IR
Internal port scan + admin share access	Medium-High	30 minutes	Investigate source host, check EDR telemetry
RDP brute force from internal host	Medium	1 hour	Verify if legitimate admin activity, check host
Unusual DNS query volume	Low-Medium	4 hours	Check for DNS tunneling, correlate with other alerts

Key Concepts

Term	Definition
Ransomware Precursor	Network activity that precedes ransomware encryption, including C2 communication, lateral movement, and data staging
Dwell Time	Time between initial compromise and ransomware deployment, averaging 21 days but sometimes as short as 17 minutes
Initial Access Broker (IAB)	Threat actors who sell compromised network access to ransomware operators on dark web markets
Beaconing	Periodic C2 callbacks from implants (Cobalt Strike, Sliver) that can be detected by analyzing connection timing patterns
Kerberoasting	Credential harvesting technique requesting Kerberos service tickets for offline cracking, detectable via unusual TGS-REQ patterns
DCSync	Technique using Directory Replication Service to extract password hashes from domain controllers, critical ransomware precursor

Tools & Systems

• Zeek (formerly Bro): Network analysis framework generating structured logs for SMB, Kerberos, DNS, HTTP, and TLS connections
• Suricata: High-performance IDS/IPS with protocol analysis and multi-threading support for ransomware signature detection
• Arkime (formerly Moloch): Full packet capture and search platform for deep forensic investigation of network events
• RITA (Real Intelligence Threat Analytics): Open-source tool for detecting beaconing, DNS tunneling, and long connections in Zeek logs
• AC-Hunter: Network threat hunting platform from Active Countermeasures for beacon detection and C2 identification

Common Scenarios

Scenario: Detecting LockBit Precursors in a Manufacturing Network

Context: A manufacturing company's SOC receives an alert for unusual SMB traffic from a workstation (10.1.5.42) in the engineering department. The workstation connected to 47 internal hosts on port 445 within 5 minutes at 2:00 AM.

Approach:

1. Zeek conn.log analysis shows 10.1.5.42 initiated connections to 47 unique internal IPs on port 445, 135, and 3389 between 01:55-02:05
2. Zeek ssl.log reveals an outbound HTTPS connection to 185.x.x.x every 60 seconds with consistent 48-byte payloads (Cobalt Strike beacon pattern)
3. RITA beacon analysis confirms high beacon score (0.96) for the external IP with 60-second jitter
4. Zeek kerberos.log shows TGS-REQ for multiple SPN accounts from 10.1.5.42 (Kerberoasting)
5. SMB tree_connect events show access to ADMIN$ shares on 12 hosts (lateral movement staging)
6. Containment: Host isolated, credentials for engineering user reset, blocking rule for C2 IP deployed
7. Full IR initiated before ransomware deployment could begin

Pitfalls:

• Dismissing internal port scans as vulnerability scanner activity without verifying the source is an authorized scanner
• Not correlating individual low-severity alerts (DNS anomaly + SMB access + failed logins) into a high-severity chain
• Setting detection thresholds too high to avoid false positives, missing low-and-slow reconnaissance
• Ignoring encrypted traffic analysis (JA3/JA4 fingerprinting) that can identify Cobalt Strike even in TLS tunnels

Output Format

## Ransomware Precursor Detection Alert

**Alert ID**: [SIEM-generated ID]
**Detection Time**: [Timestamp]
**Source Host**: [IP / Hostname]
**Confidence**: [High / Medium / Low]
**Kill Chain Phase**: [Initial Access / C2 / Credential Harvest / Recon / Lateral Movement / Staging]

### Indicators Detected
| Indicator | Source | Detail | MITRE ATT&CK |
|-----------|--------|--------|--------------|
| [Type] | [Zeek/Suricata/SIEM] | [Description] | [T-ID] |

### Correlation Chain
1. [Timestamp] - [Event 1]
2. [Timestamp] - [Event 2]
3. [Timestamp] - [Event 3]

### Recommended Actions
- [ ] Isolate source host from network
- [ ] Check EDR telemetry for host-based indicators
- [ ] Reset credentials for affected user accounts
- [ ] Block identified C2 infrastructure
- [ ] Escalate to incident response team

Other files in this skill

• LICENSE
• assets/template.md
• references/api-reference.md
• references/standards.md
• references/workflows.md
• scripts/agent.py
• scripts/process.py

assets/template.md (verbatim)

Ransomware Precursor Detection Deployment Template

Network Sensor Placement

Sensor Location	TAP/SPAN	Sensor Type	Protocols Monitored
Internet Edge		Zeek + Suricata	All outbound
DC Segment		Zeek	Kerberos, LDAP, SMB, DNS
Server VLAN		Zeek + Suricata	SMB, RDP, WMI, WinRM
Workstation VLAN		Zeek	SMB, HTTP/S, DNS

Detection Rules Deployed

Rule ID	Category	Description	Severity	Status
	C2 Beaconing
	Credential Harvest
	Internal Scanning
	Lateral Movement

Threat Intelligence Feeds

Feed	Source	Update Frequency	IOC Types
Feodo Tracker	abuse.ch	Hourly	IPs (C2)
ThreatFox	abuse.ch	Hourly	IPs, domains, hashes
ET Open Rules	Proofpoint	Daily	Suricata signatures
CISA KEV	CISA	As published	CVEs

Alert Triage SLAs

Category	Priority	Triage SLA	Escalation Path
Confirmed C2	CRITICAL	15 min	SOC -> IR Team -> CISO
Credential Harvest	CRITICAL	15 min	SOC -> IR Team
Internal Scanning	HIGH	30 min	SOC -> IR Team
Admin Share Enum	HIGH	30 min	SOC -> IR Team
RDP Anomaly	MEDIUM	1 hour	SOC Tier 2
DNS Anomaly	LOW	4 hours	SOC Tier 1

Detection Tuning Log

Date	Rule	Change	Reason	FP Rate Before	FP Rate After

references/api-reference.md (verbatim)

API Reference — Detecting Ransomware Precursors in Network Traffic

Zeek (Bro) Log Fields

conn.log

Field	Type	Description
ts	time	Connection start timestamp (Unix epoch)
id.orig_h	addr	Source IP address
id.orig_p	port	Source port
id.resp_h	addr	Destination IP address
id.resp_p	port	Destination port
proto	enum	Transport protocol (tcp/udp/icmp)
orig_bytes	count	Bytes sent by originator
resp_bytes	count	Bytes sent by responder
conn_state	string	Connection state (SF=normal, S0=no reply, REJ=rejected)
duration	interval	Duration of connection

smb_files.log

Field	Type	Description
action	enum	SMB action (SMB_FILE_OPEN, SMB_FILE_WRITE, SMB_FILE_DELETE)
path	string	Full UNC path accessed
name	string	Filename
size	count	File size in bytes
id.orig_h	addr	Source host (accessor)
id.resp_h	addr	Target host

kerberos.log

Field	Type	Description
request_type	string	KRB_AS_REQ, KRB_TGS_REQ
client	string	Client principal
service	string	Service principal (SPN)
success	bool	Whether request succeeded
error_msg	string	Error type (e.g., KDC_ERR_PREAUTH_REQUIRED)

Suricata CLI

Start in IDS mode

suricata -c /etc/suricata/suricata.yaml -i eth0

Start in IPS mode (NFQUEUE)

suricata -c /etc/suricata/suricata.yaml -q 0
# Configure iptables to send traffic to NFQUEUE:
iptables -I FORWARD -j NFQUEUE --queue-num 0

Run on pcap file

suricata -c /etc/suricata/suricata.yaml -r capture.pcap -l /var/log/suricata/

Update rules with suricata-update

suricata-update                          # Update all enabled sources
suricata-update list-sources             # List available rule sources
suricata-update enable-source et/open    # Enable Emerging Threats Open
suricata-update enable-source ptresearch/attackdetection  # PT Research rules
suricata-update update-sources           # Refresh source index
suricata-update --no-reload              # Update without live reload

Reload rules without restart

kill -USR2 $(pidof suricata)
# Or via Unix socket:
suricatasc -c reload-rules

Query eve.json for alerts

# Ransomware-related alerts in last hour
jq 'select(.event_type=="alert") | select(.alert.signature | test("ransomware|cobalt|mimikatz|psexec";"i"))' \
  /var/log/suricata/eve.json | jq -r '[.timestamp,.src_ip,.dest_ip,.alert.signature] | @tsv'

# Top 10 alert signatures
jq -r 'select(.event_type=="alert") | .alert.signature' /var/log/suricata/eve.json | \
  sort | uniq -c | sort -rn | head -10

RITA (Real Intelligence Threat Analytics)

Import Zeek logs and analyze

rita import --input /var/log/zeek/current/ --database my_network
rita analyze my_network

Beacon detection output

rita show-beacons my_network --human-readable
# Columns: Score | Source | Dest | Connections | Avg Bytes | TS Delta
# Score 0.9+ = high confidence beacon

DNS tunneling detection

rita show-exploded-dns my_network | head -20
rita show-long-connections my_network --human-readable

Splunk SPL — Ransomware Precursor Queries

Internal lateral movement via SMB/RDP/WinRM

index=zeek sourcetype=zeek_conn
  id.resp_p IN (445, 135, 3389, 5985, 5986)
  id.orig_h IN 10.0.0.0/8
  id.resp_h IN 10.0.0.0/8
| stats dc(id.resp_h) as targets count as conns by id.orig_h
| where targets >= 10
| sort -targets

Detect beaconing (regular connection intervals)

index=zeek sourcetype=zeek_conn
| bucket _time span=1m
| stats count as conns by id.orig_h, id.resp_h, id.resp_p, _time
| stats stdev(conns) as jitter avg(conns) as avg_conns count as minutes
    by id.orig_h, id.resp_h, id.resp_p
| where minutes > 10 AND jitter < 2 AND avg_conns > 0
| eval beacon_score = round(1 - (jitter / (avg_conns + 0.001)), 2)
| where beacon_score > 0.8
| sort -beacon_score

abuse.ch Threat Intelligence Feeds

Feodo Tracker (C2 IPs — Cobalt Strike, BazarLoader)

# CSV format: first_seen,dst_ip,dst_port,c2_status,malware
curl -s https://feodotracker.abuse.ch/downloads/ipblocklist.csv | \
  grep -v "^#" | awk -F, '{print $2}' > /tmp/c2_ips.txt

ThreatFox IOC API

# Query recent ransomware IOCs
curl -s -X POST https://threatfox-api.abuse.ch/api/v1/ \
  -H "Content-Type: application/json" \
  -d '{"query":"get_iocs","days":7,"tag":"ransomware"}' | \
  jq '.data[] | [.ioc_value,.ioc_type,.malware,.confidence_level] | @tsv' -r

MITRE ATT&CK Ransomware Precursor Techniques

Technique	ID	Network Indicator
Remote Services: SMB/WMI	T1021.002	SMB port 445 traffic to many hosts
OS Credential Dumping: DCSync	T1003.006	DRS GetNCChanges from non-DC
Kerberoasting	T1558.003	TGS-REQ for many SPNs
Command & Control	T1071.001	Regular HTTPS beaconing
Lateral Tool Transfer	T1570	Large SMB file writes across hosts
Network Service Scanning	T1046	Port sweeps on 445/3389/135

references/standards.md (verbatim)

Standards & References - Detecting Ransomware Precursors

MITRE ATT&CK Mapping

Initial Access (TA0001)

• T1078: Valid Accounts (compromised credentials from IABs)
• T1133: External Remote Services (VPN/RDP exploitation)
• T1566: Phishing (email-based initial access)

Command and Control (TA0011)

• T1071.001: Application Layer Protocol: Web (HTTPS beacons)
• T1071.004: Application Layer Protocol: DNS (DNS tunneling)
• T1573: Encrypted Channel (C2 over TLS)
• T1090: Proxy (redirectors and relay infrastructure)

Credential Access (TA0006)

• T1558.003: Kerberoasting
• T1003.006: DCSync
• T1557: Adversary-in-the-Middle (NTLM relay)

Discovery (TA0007)

• T1046: Network Service Discovery (port scanning)
• T1018: Remote System Discovery (AD enumeration)
• T1087: Account Discovery

Lateral Movement (TA0008)

• T1021.002: Remote Services: SMB/Windows Admin Shares
• T1021.001: Remote Services: RDP
• T1047: Windows Management Instrumentation (WMI)
• T1569.002: System Services: Service Execution (PsExec)

Industry References

CISA Advisories

• AA23-136A: #StopRansomware - BianLian Ransomware Group
• AA23-158A: #StopRansomware - CL0P Ransomware Gang
• AA24-131A: #StopRansomware - Black Basta
• AA23-165A: Understanding Ransomware Threat Actors: LockBit

NIST

• SP 800-94 Rev 1: Guide to Intrusion Detection and Prevention Systems
• SP 800-86: Guide to Integrating Forensic Techniques into Incident Response
• IR 8374: Ransomware Risk Management

Threat Intelligence Sources

• abuse.ch Feodo Tracker: https://feodotracker.abuse.ch/
• abuse.ch ThreatFox: https://threatfox.abuse.ch/
• CISA Known Exploited Vulnerabilities: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• Emerging Threats Ruleset: https://rules.emergingthreats.net/

references/workflows.md (verbatim)

Workflows - Detecting Ransomware Precursors in Network

Workflow 1: Network Sensor Deployment

Start
  |
  v
[Identify network chokepoints] --> Core switches, internet edge, DC segments
  |
  v
[Deploy network TAPs or configure SPAN ports]
  |
  v
[Install Zeek sensor] --> Configure local.zeek with site-specific networks
  |
  v
[Install Suricata IDS] --> Load ET Open + custom ransomware rules
  |
  v
[Configure log forwarding to SIEM]
  |-- Zeek: conn.log, ssl.log, dns.log, smb.log, kerberos.log, notice.log
  |-- Suricata: eve.json (alerts, flow, dns, tls)
  |
  v
[Deploy RITA for beacon analysis] --> Schedule hourly Zeek log imports
  |
  v
[Load threat intelligence feeds] --> Feodo, ThreatFox, CISA KEV
  |
  v
[Validate detection with controlled Cobalt Strike beacon test]
  |
  v
End

Workflow 2: Alert Triage for Ransomware Precursors

Alert Received
  |
  v
[Classify alert type]
  |-- C2 Beaconing --> Priority: CRITICAL, SLA: 15 min
  |-- Credential Harvesting --> Priority: CRITICAL, SLA: 15 min
  |-- Internal Scanning --> Priority: HIGH, SLA: 30 min
  |-- Admin Share Access --> Priority: HIGH, SLA: 30 min
  |-- RDP Brute Force --> Priority: MEDIUM, SLA: 1 hour
  |-- DNS Anomaly --> Priority: LOW, SLA: 4 hours
  |
  v
[Check for correlated alerts on same source IP]
  |-- Multiple categories? --> Elevate to CRITICAL regardless
  |-- Single category? --> Proceed with category SLA
  |
  v
[Verify source host context]
  |-- Known admin workstation? --> Check if scheduled activity
  |-- Server? --> Check for authorized maintenance window
  |-- Standard workstation? --> Likely compromise indicator
  |
  v
[Decision: True Positive or False Positive?]
  |
  TP --> [Contain host: network isolation via NAC/EDR]
  |       |
  |       v
  |       [Trigger incident response playbook]
  |
  FP --> [Document FP reason]
          |
          v
          [Update detection rule to reduce FP rate]
          |
          v
          End

Workflow 3: Beacon Detection with RITA

Hourly Cron Job
  |
  v
[Import latest Zeek logs into RITA database]
  $ rita import /opt/zeek/logs/current rita-db
  |
  v
[Analyze beacons]
  $ rita show-beacons rita-db --human-readable
  |
  v
[Filter results by beacon score > 0.7]
  |
  v
[For each high-score beacon:]
  |-- Look up destination IP in threat intel
  |-- Check JA3/JA4 hash against known C2 fingerprints
  |-- Verify beacon interval and jitter pattern
  |
  v
[Score > 0.9 AND matches threat intel?]
  |
  Yes --> [Generate CRITICAL alert]
  |
  No --> [Score > 0.7?]
          |
          Yes --> [Generate MEDIUM alert for analyst review]
          |
          No --> [Log and continue monitoring]
  |
  v
End

Back to mukul975/Anthropic-Cybersecurity-Skills (817 security skills) or Agent skills.