This commit is contained in:
2025-11-21 21:34:39 +02:00
parent 8261b4bc35
commit 02e6e9028a
9 changed files with 36 additions and 72 deletions

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@@ -1,13 +1,10 @@
#!/usr/bin/env bash #!/usr/bin/env bash
# dns_bpf_correlate.sh # dns_bpf_correlate_fixed.sh
# Usage: sudo ./dns_bpf_correlate.sh
#
# Requires: bpftrace, tcpdump, date (GNU)
# Purpose: correlate DNS packets (tcpdump) with the process that issued them using bpftrace syscall tracing.
set -u set -u
DOMAIN=$1 DOMAIN="tracker1.myporn.club"
WINDOW_MS=2000 # how many ms back to search for matching bpftrace events WINDOW_MS=2000
HALF_WINDOW_MS=$((WINDOW_MS/2))
BASE_TS="$(date +%Y%m%d_%H%M%S)" BASE_TS="$(date +%Y%m%d_%H%M%S)"
DNSLOG="${DOMAIN}_${BASE_TS}_dns.log" DNSLOG="${DOMAIN}_${BASE_TS}_dns.log"
BPFLOG="bpftrace_${BASE_TS}.log" BPFLOG="bpftrace_${BASE_TS}.log"
@@ -19,12 +16,12 @@ RED="\e[31m"; GREEN="\e[32m"; YELLOW="\e[33m"; BLUE="\e[34m"; RESET="\e[0m"
TCPDUMP_PID="" TCPDUMP_PID=""
BPF_PID="" BPF_PID=""
now_ms() { date +%s%3N; } # epoch milliseconds (GNU date) now_ms() { date +%s%3N; }
cleanup() { cleanup() {
echo -e "${BLUE}[*] Stopping background processes...${RESET}" echo -e "${BLUE}[*] Stopping background processes...${RESET}"
[[ -n "$TCPDUMP_PID" ]] && sudo kill "$TCPDUMP_PID" 2>/dev/null || true [[ -n "$TCPDUMP_PID" ]] && kill "$TCPDUMP_PID" 2>/dev/null || true
[[ -n "$BPF_PID" ]] && sudo kill "$BPF_PID" 2>/dev/null || true [[ -n "$BPF_PID" ]] && kill "$BPF_PID" 2>/dev/null || true
sleep 0.1 sleep 0.1
echo -e "${BLUE}[*] Done.${RESET}" echo -e "${BLUE}[*] Done.${RESET}"
exit 0 exit 0
@@ -35,64 +32,50 @@ echo -e "${BLUE}[*] Domain: ${YELLOW}$DOMAIN${RESET}"
echo -e "${BLUE}[*] DNS log: ${YELLOW}$DNSLOG${RESET}" echo -e "${BLUE}[*] DNS log: ${YELLOW}$DNSLOG${RESET}"
echo -e "${BLUE}[*] bpftrace log: ${YELLOW}$BPFLOG${RESET}" echo -e "${BLUE}[*] bpftrace log: ${YELLOW}$BPFLOG${RESET}"
echo -e "${BLUE}[*] Incidents directory: ${YELLOW}$INCIDENT_DIR${RESET}" echo -e "${BLUE}[*] Incidents directory: ${YELLOW}$INCIDENT_DIR${RESET}"
echo -e "${BLUE}[*] Window for correlation: ${YELLOW}${WINDOW_MS} ms${RESET}" echo -e "${BLUE}[*] Window for correlation: ${YELLOW}${WINDOW_MS} ms${HALF_WINDOW_MS} ms)${RESET}"
echo "" echo ""
# Start tcpdump -> DNSLOG (writes raw tcpdump lines) # Start tcpdump
sudo tcpdump -n -i any port 53 -s0 -ttt -l 2>/dev/null >> "$DNSLOG" & tcpdump -n -i any port 53 -s0 -ttt -l 2>/dev/null >> "$DNSLOG" &
TCPDUMP_PID=$! TCPDUMP_PID=$!
echo -e "${GREEN}[*] tcpdump started (PID $TCPDUMP_PID)${RESET}" echo -e "${GREEN}[*] tcpdump started (PID $TCPDUMP_PID)${RESET}"
# Start bpftrace inline printing epoch seconds + ms and PID/COMM/FD # Start bpftrace inline (correct syntax)
# We print: <epoch_s>.<ms> PID=<pid> COMM=<comm> FD=<fd> bpftrace -e '
# Use time (seconds since epoch) and nsecs to produce ms fraction.
sudo bpftrace -e '
tracepoint:syscalls:sys_enter_sendto tracepoint:syscalls:sys_enter_sendto
{ {
$s = time; // seconds since epoch $s = time; $ms = nsecs/1000000 % 1000;
$ms = (nsecs/1000000) % 1000;
printf("%d.%03d PID=%d COMM=%s FD=%d\n", $s, $ms, pid, comm, args->fd); printf("%d.%03d PID=%d COMM=%s FD=%d\n", $s, $ms, pid, comm, args->fd);
} }
' > "$BPFLOG" 2>/dev/null & ' > "$BPFLOG" 2>/dev/null &
BPF_PID=$! BPF_PID=$!
sleep 0.2 sleep 0.2
# Quick liveness check for bpftrace log (it may stay empty until events occur, but we ensure process exists)
if ! kill -0 "$BPF_PID" 2>/dev/null; then if ! kill -0 "$BPF_PID" 2>/dev/null; then
echo -e "${YELLOW}[!] bpftrace failed to start (process exited). Check bpftrace availability and permissions.${RESET}" echo -e "${RED}[!] bpftrace failed to start!${RESET}"
echo -e "${YELLOW} Try: sudo bpftrace -e 'tracepoint:syscalls:sys_enter_sendto { printf(\"hi\\n\"); }'${RESET}"
cleanup cleanup
fi fi
echo -e "${GREEN}[*] bpftrace started (PID $BPF_PID)${RESET}"
# Wait a short moment and check file is being appended to (if no events yet file may be empty - warn instead of failing)
sleep 1 sleep 1
if [[ ! -s "$BPFLOG" ]]; then
echo -e "${YELLOW}[!] Note: bpftrace log is currently empty (no sendto events observed yet). This is normal until a process performs sendto().${RESET}"
fi
echo -e "${GREEN}[*] bpftrace started (PID $BPF_PID) -- logging to $BPFLOG${RESET}"
echo "" echo ""
# Helper: gather proc info for PID # Helper function: /proc info for PID
proc_info_for_pid() { proc_info_for_pid() {
local pid="$1" local pid="$1"
if [[ -r "/proc/$pid/cmdline" ]]; then if [[ -r "/proc/$pid/cmdline" ]]; then
local exe local exe=$(readlink -f "/proc/$pid/exe" 2>/dev/null || true)
exe=$(sudo readlink -f "/proc/$pid/exe" 2>/dev/null || true) local cmd=$(tr '\0' ' ' < "/proc/$pid/cmdline" 2>/dev/null || true)
local cmd
cmd=$(sudo tr '\0' ' ' < "/proc/$pid/cmdline" 2>/dev/null || true)
echo "pid=$pid exe=${exe:-N/A} cmdline='${cmd:-N/A}'" echo "pid=$pid exe=${exe:-N/A} cmdline='${cmd:-N/A}'"
else else
echo "pid=$pid (no /proc info)" echo "pid=$pid (no /proc info)"
fi fi
} }
# Tail dns log and correlate with bpftrace by timestamp # Tail tcpdump and correlate symmetrically
tail -Fn0 "$DNSLOG" | while IFS= read -r dnsline; do tail -Fn0 "$DNSLOG" | while IFS= read -r dnsline; do
# case-insensitive match for domain
if echo "$dnsline" | grep -qi -- "$DOMAIN"; then if echo "$dnsline" | grep -qi -- "$DOMAIN"; then
detect_ms=$(now_ms) detect_ms=$(now_ms)
echo -e "${RED}[!] Suspicious DNS request detected @ ${YELLOW}${detect_ms}${RESET}" echo -e "${RED}[!] Suspicious DNS request detected @${YELLOW}$detect_ms${RESET}"
echo -e "${YELLOW}$dnsline${RESET}" echo -e "${YELLOW}$dnsline${RESET}"
echo "" echo ""
@@ -104,66 +87,51 @@ tail -Fn0 "$DNSLOG" | while IFS= read -r dnsline; do
echo "detected_at_ms: $detect_ms" echo "detected_at_ms: $detect_ms"
} > "$INCIDENT_FILE" } > "$INCIDENT_FILE"
# extract src token (token after IP token) # extract source IP/port
src_tok=$(echo "$dnsline" | awk '{for(i=1;i<=NF;i++) if($i=="IP" || $i=="IP6"){print $(i+1); exit}}' || true) src_tok=$(echo "$dnsline" | awk '{for(i=1;i<=NF;i++) if($i=="IP" || $i=="IP6"){print $(i+1); exit}}' || true)
if [[ -n "$src_tok" ]]; then if [[ -n "$src_tok" ]]; then
srcPort="${src_tok##*.}" srcPort="${src_tok##*.}"
srcIP="${src_tok%.*}" srcIP="${src_tok%.*}"
echo -e "${GREEN}[+] Extracted source: IP=${YELLOW}${srcIP}${RESET} PORT=${YELLOW}${srcPort}${RESET}" echo -e "${GREEN}[+] Extracted source: IP=${YELLOW}$srcIP${RESET} PORT=${YELLOW}$srcPort${RESET}"
echo "extracted_src_ip: $srcIP" >> "$INCIDENT_FILE" echo "extracted_src_ip: $srcIP" >> "$INCIDENT_FILE"
echo "extracted_src_port: $srcPort" >> "$INCIDENT_FILE" echo "extracted_src_port: $srcPort" >> "$INCIDENT_FILE"
else
echo -e "${YELLOW}[!] Could not extract source IP/port from tcpdump line${RESET}"
echo "extracted_src_ip: N/A" >> "$INCIDENT_FILE"
echo "extracted_src_port: N/A" >> "$INCIDENT_FILE"
fi fi
# Search BPFLOG for events within WINDOW_MS before detection # Symmetric window: half before, half after
# BPF lines start like: 1600000000.123 PID=123 COMM=foo FD=... low_ms=$((detect_ms - HALF_WINDOW_MS))
low_ms=$((detect_ms - WINDOW_MS)) high_ms=$((detect_ms + HALF_WINDOW_MS))
high_ms=$((detect_ms))
awk -v low="$low_ms" -v high="$high_ms" ' awk -v low="$low_ms" -v high="$high_ms" '
BEGIN{FS=" "; OFS=" "} BEGIN{FS=" "; OFS=" "}
{ {
# parse first token as seconds.ms
if ($1 ~ /^[0-9]+\.[0-9]{3}$/) { if ($1 ~ /^[0-9]+\.[0-9]{3}$/) {
split($1, a, ".") split($1, a, ".")
t_s = a[1]; t_ms = a[2] t_s=a[1]; t_ms=a[2]; t=t_s*1000+t_ms
t = t_s * 1000 + t_ms
if (t >= low && t <= high) print $0 if (t >= low && t <= high) print $0
} }
}' "$BPFLOG" | tee -a "$INCIDENT_FILE" > /tmp/_bpf_matches.$$ || true }' "$BPFLOG" | tee -a "$INCIDENT_FILE" > /tmp/_bpf_matches.$$ || true
if [[ -s /tmp/_bpf_matches.$$ ]]; then if [[ -s /tmp/_bpf_matches.$$ ]]; then
echo -e "${GREEN}[+] bpftrace events found within ${WINDOW_MS} ms:${RESET}" echo -e "${GREEN}[+] bpftrace events found in ±${HALF_WINDOW_MS}ms window:${RESET}"
sed 's/^/ /' /tmp/_bpf_matches.$$ sed 's/^/ /' /tmp/_bpf_matches.$$
echo "" >> "$INCIDENT_FILE"
echo "bpftrace_matches:" >> "$INCIDENT_FILE" echo "bpftrace_matches:" >> "$INCIDENT_FILE"
cat /tmp/_bpf_matches.$$ >> "$INCIDENT_FILE" cat /tmp/_bpf_matches.$$ >> "$INCIDENT_FILE"
# extract PIDs
pids=$(sed -n 's/.*PID=\([0-9]\+\).*/\1/p' /tmp/_bpf_matches.$$ | sort -u) pids=$(sed -n 's/.*PID=\([0-9]\+\).*/\1/p' /tmp/_bpf_matches.$$ | sort -u)
if [[ -n "$pids" ]]; then for pid in $pids; do
echo -e "${GREEN}[+] Candidate PIDs: ${YELLOW}$pids${RESET}" info=$(proc_info_for_pid "$pid")
echo "" >> "$INCIDENT_FILE" echo " [*] $info"
echo "candidate_pids:" >> "$INCIDENT_FILE" echo " - $info" >> "$INCIDENT_FILE"
for pid in $pids; do done
info=$(proc_info_for_pid "$pid")
echo " - $info"
echo " - $info" >> "$INCIDENT_FILE"
done
fi
else else
echo -e "${YELLOW}[!] No bpftrace events found in window (this can happen if syscall happened >${WINDOW_MS}ms before tcpdump line or bpftrace didn't capture).${RESET}" echo -e "${YELLOW}[!] No bpftrace events in window${RESET}"
echo "bpftrace_matches: NONE in ${WINDOW_MS}ms window" >> "$INCIDENT_FILE" echo "bpftrace_matches: NONE in ±${HALF_WINDOW_MS}ms" >> "$INCIDENT_FILE"
fi fi
# append an ss snapshot for context
echo "" >> "$INCIDENT_FILE" echo "" >> "$INCIDENT_FILE"
echo "ss_snapshot:" >> "$INCIDENT_FILE" echo "ss_snapshot:" >> "$INCIDENT_FILE"
sudo ss -tulpn 2>/dev/null >> "$INCIDENT_FILE" || true ss -tulpn 2>/dev/null >> "$INCIDENT_FILE" || true
echo -e "${GREEN}[+] Incident saved to ${YELLOW}${INCIDENT_FILE}${RESET}" echo -e "${GREEN}[+] Incident saved to ${YELLOW}$INCIDENT_FILE${RESET}"
echo -e "${BLUE}------------------------------------------------------${RESET}" echo -e "${BLUE}------------------------------------------------------${RESET}"
echo "" echo ""
rm -f /tmp/_bpf_matches.$$ rm -f /tmp/_bpf_matches.$$

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