Realizando Forense de Rede com Wireshark

Quando Usar

• Ao analisar tráfego de rede capturado (arquivos PCAP) de um incidente de segurança
• Para identificar comunicações de comando e controle (C2) em tráfego capturado
• Ao reconstruir atividades de exfiltração de dados a partir de capturas de pacotes
• Durante a análise de malware para identificar indicadores de comprometimento de rede
• Para extrair arquivos, credenciais e artefatos transferidos pela rede

Pré-requisitos

• Wireshark ou tshark instalados para análise de pacotes
• Arquivos PCAP/PCAPNG de capturas de rede (tcpdump, Wireshark, TAP de rede)
• NetworkMiner para extração automatizada de artefatos
• RAM suficiente para arquivos de captura grandes (PCAPs de 1GB+ precisam de 8GB+ de RAM)
• Compreensão dos protocolos TCP/IP, HTTP, DNS, TLS
• Bancos de dados GeoIP para geolocalização de IP

Fluxo de Trabalho

Passo 1: Preparar e Validar o Arquivo de Captura

# Install Wireshark and tshark
sudo apt-get install wireshark tshark

# Verify the PCAP file
capinfos /cases/case-2024-001/network/capture.pcap

# Output includes: file type, packet count, capture duration, data size
# Example output:
# File name:           capture.pcap
# File type:           Wireshark/tcpdump/... - pcap
# Number of packets:   1,245,678
# File size:           856 MB
# Data size:           823 MB
# Capture duration:    3600.123456 seconds
# First packet time:   2024-01-15 14:00:00.000000
# Last packet time:    2024-01-15 15:00:00.123456

# Hash the PCAP for integrity
sha256sum /cases/case-2024-001/network/capture.pcap \
   > /cases/case-2024-001/network/pcap_hash.txt

# Get a protocol hierarchy statistics overview
tshark -r /cases/case-2024-001/network/capture.pcap -q -z io,phs

Passo 2: Filtrar e Identificar Tráfego Suspeito

# Extract conversation statistics
tshark -r /cases/case-2024-001/network/capture.pcap -q -z conv,tcp

# Find top talkers by bytes transferred
tshark -r /cases/case-2024-001/network/capture.pcap -q -z endpoints,ip \
   | sort -t$'\t' -k3 -rn | head -20

# Filter for DNS queries (potential C2 or exfiltration)
tshark -r /cases/case-2024-001/network/capture.pcap \
   -Y "dns.qr == 0" \
   -T fields -e frame.time -e ip.src -e dns.qry.name \
   > /cases/case-2024-001/analysis/dns_queries.txt

# Find DNS queries to unusual TLDs or long domain names (DNS tunneling)
tshark -r /cases/case-2024-001/network/capture.pcap \
   -Y "dns.qr == 0 && dns.qry.name matches \"[a-z0-9]{30,}\"" \
   -T fields -e frame.time -e ip.src -e dns.qry.name \
   > /cases/case-2024-001/analysis/suspicious_dns.txt

# Filter HTTP traffic
tshark -r /cases/case-2024-001/network/capture.pcap \
   -Y "http.request" \
   -T fields -e frame.time -e ip.src -e ip.dst -e http.request.method \
   -e http.host -e http.request.uri -e http.user_agent \
   > /cases/case-2024-001/analysis/http_requests.txt

# Find connections to known malicious ports
tshark -r /cases/case-2024-001/network/capture.pcap \
   -Y "tcp.dstport == 4444 || tcp.dstport == 8080 || tcp.dstport == 1337 || tcp.dstport == 6667" \
   -T fields -e frame.time -e ip.src -e ip.dst -e tcp.dstport \
   > /cases/case-2024-001/analysis/suspicious_ports.txt

# Detect beaconing patterns (regular interval connections)
tshark -r /cases/case-2024-001/network/capture.pcap \
   -Y "ip.dst == 185.0.0.1" \
   -T fields -e frame.time_epoch \
   > /tmp/beacon_times.txt

Passo 3: Extrair Arquivos e Objetos do Tráfego

# Exportar objetos HTTP (arquivos transferidos via HTTP)
tshark -r /cases/case-2024-001/network/capture.pcap \
   --export-objects http,/cases/case-2024-001/analysis/http_objects/

# Exportar objetos SMB
tshark -r /cases/case-2024-001/network/capture.pcap \
   --export-objects smb,/cases/case-2024-001/analysis/smb_objects/

# Exportar objetos DICOM (imagens médicas)
tshark -r /cases/case-2024-001/network/capture.pcap \
   --export-objects dicom,/cases/case-2024-001/analysis/dicom_objects/

# Exportar transferências de dados FTP
tshark -r /cases/case-2024-001/network/capture.pcap \
   -Y "ftp-data" \
   -T fields -e ftp-data.data \
   --export-objects ftp-data,/cases/case-2024-001/analysis/ftp_objects/

# Gerar hash de todos os objetos extraídos
find /cases/case-2024-001/analysis/http_objects/ -type f -exec sha256sum {} \; \
   > /cases/case-2024-001/analysis/extracted_file_hashes.txt

# Verificar hashes de arquivos extraídos contra o VirusTotal
while read hash filepath; do
   echo "Verificando $filepath ($hash)"
   curl -s "https://www.virustotal.com/api/v3/files/$hash" \
      -H "x-apikey: SUA_CHAVE_API" | python3 -c "

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