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fix(vuln): reduce SSTI false positives with unique canary + baseline #186

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fix(vuln): reduce SSTI false positives with unique canary + baseline #186

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18 changes: 14 additions & 4 deletions bughunter/tools/vuln_scanner.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -377,21 +377,31 @@ if ! skip_has ssti; then
if [ -s "$PARAMS_FILE" ]; then
# Removed associative array for Bash 3.2 compatibility
# engines: jinja2, freemarker, thymeleaf, erb
# Use a unique math canary instead of 7*7→49. Matching "\b49\b" false-
# positives on normal page content (CSS, durations, IDs). Also require
# the canary to be absent from a baseline (uninjected) response so
# reflected-but-unevaluated payloads are not treated as confirmed SSTI.
SSTI_ENGINES=("jinja2" "freemarker" "thymeleaf" "erb")
SSTI_PAYLOADS=("{{7*7}}" "\${7*7}" "*{7*7}" "<%= 7*7 %>")

SSTI_PAYLOADS=("{{739391*739391}}" "\${739391*739391}" "*{739391*739391}" "<%= 739391*739391 %>")
SSTI_CANARY="546699042881"

SSTI_LIMIT=$([ "$QUICK_MODE" = "--quick" ] && echo 20 || echo 50)
log_step "Testing SSTI payloads on up to $SSTI_LIMIT URLs..."
log_step "Testing SSTI payloads on up to $SSTI_LIMIT URLs (canary $SSTI_CANARY + baseline)..."
hit=0
while IFS= read -r url; do
[ -z "$url" ] && continue
baseline=$(curl -sk --max-time 10 ${BB_AUTH_ARGS[@]+"${BB_AUTH_ARGS[@]}"} "$url" 2>/dev/null || true)
if echo "$baseline" | grep -q "$SSTI_CANARY"; then
log_step "Baseline already contains canary — skipping: $url"
continue
fi
for idx in "${!SSTI_ENGINES[@]}"; do
engine="${SSTI_ENGINES[$idx]}"
payload="${SSTI_PAYLOADS[$idx]}"
enc_payload=$(python3 -c "import urllib.parse; print(urllib.parse.quote('''$payload'''))" 2>/dev/null || echo "$payload")
injected=$(echo "$url" | sed "s/=\([^&]*\)/=${enc_payload}/g")
body=$(curl -sk --max-time 10 ${BB_AUTH_ARGS[@]+"${BB_AUTH_ARGS[@]}"} "$injected" 2>/dev/null || true)
if echo "$body" | grep -qE '(\b49\b|7777777)'; then
if echo "$body" | grep -q "$SSTI_CANARY"; then
log_crit "SSTI confirmed [$engine]: $injected"
echo "[CONFIRMED] [SSTI-CONFIRMED] engine=$engine url=$injected" >> "$SSTI_OUT"
hit=$(( hit + 1 ))
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