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train_risk_model.py

99 lines3,977 bytessha256 cb71b554884e
  1. """Train a linear risk-score model (0-100) on the LEASH merchant dataset.
  2. Model: logistic regression over engineered features (numeric + boolean
  3. flags + missingness indicators), trained on the label
  4. (confirmed_malicious vs likely_legitimate). The output probability is
  5. scaled to a 0-100 risk score.
  6. Usage:
  7. .venv/bin/python train_risk_model.py
  8. """
  9. import numpy as np
  10. import pandas as pd
  11. from sklearn.linear_model import LogisticRegression
  12. from sklearn.metrics import roc_auc_score
  13. from sklearn.model_selection import train_test_split
  14. CSV_PATH = "data/processed/dataset_features.csv"
  15. MODEL_OUT = "models/risk_score_linear.json"
  16. # Behavioral + threat features present in the data. Registry fields are
  17. # excluded as raw features (they only exist for companies -> the model
  18. # would just learn entity_type). Instead, HAS_REGISTRY is one feature.
  19. NUMERIC = ["company_age_days", "domain_age_days",
  20. "domain_typo_score", "brand_name_similarity"]
  21. BOOL = ["registry_found", "website_reachable", "https_enabled", "tls_valid",
  22. "dns_a_exists", "dns_mx_exists", "dns_txt_exists",
  23. "domain_privacy_proxy", "openphish_hit", "urlhaus_hit",
  24. "possible_brand_impersonation"]
  25. def engineer(df: pd.DataFrame) -> pd.DataFrame:
  26. """NaN-safe feature matrix: numerics imputed to median + indicator,
  27. booleans mapped True=1, False=0, missing=0.5 (unknown)."""
  28. X = pd.DataFrame(index=df.index)
  29. for c in NUMERIC:
  30. v = pd.to_numeric(df[c], errors="coerce")
  31. med = v.median()
  32. X[c] = v.fillna(med)
  33. X[f"{c}_missing"] = v.isna().astype(int)
  34. for c in BOOL:
  35. v = df[c]
  36. if v.dtype == object:
  37. v = v.map(lambda x: x if isinstance(x, (bool, np.bool_))
  38. else np.nan)
  39. X[c] = v.astype(float).fillna(0.5) # 0.5 = unknown
  40. # registry-based derived
  41. age = pd.to_numeric(df["company_age_days"], errors="coerce")
  42. X["young_registry"] = (age < 365).astype(float).where(age.notna(), 0.0)
  43. dage = pd.to_numeric(df["domain_age_days"], errors="coerce")
  44. X["young_domain"] = (dage < 365).astype(float).where(dage.notna(), 0.0)
  45. return X
  46. def main() -> None:
  47. df = pd.read_csv(CSV_PATH, low_memory=False)
  48. df = df[df["label"].isin(["confirmed_malicious",
  49. "likely_legitimate"])].copy()
  50. y = (df["label"] == "confirmed_malicious").astype(int)
  51. X = engineer(df)
  52. Xtr, Xte, ytr, yte = train_test_split(
  53. X, y, test_size=0.2, random_state=42, stratify=y)
  54. clf = LogisticRegression(max_iter=2000)
  55. clf.fit(Xtr, ytr)
  56. p = clf.predict_proba(Xte)[:, 1]
  57. print(f"Test ROC-AUC: {roc_auc_score(yte, p):.4f}")
  58. print(f"Risk score (0-100) on test set: "
  59. f"malicious median={100 * np.median(p[yte == 1]):.1f}, "
  60. f"legit median={100 * np.median(p[yte == 0]):.1f}")
  61. # ---- formula ---------------------------------------------------------
  62. # risk = 100 * sigmoid(b0 + sum(coef_i * x_i))
  63. coefs = pd.Series(clf.coef_[0], index=X.columns)
  64. intercept = float(clf.intercept_[0])
  65. print("\nFORMULA: risk = 100 / (1 + exp(-(b0 + sum(c_i * x_i))))")
  66. print(f"b0 (intercept) = {intercept:.4f}")
  67. print("\nCoefficients c_i:")
  68. print(coefs.round(4).sort_values(key=abs, ascending=False).to_string())
  69. # Save model artifact
  70. out = {"intercept": intercept,
  71. "coefficients": coefs.round(6).to_dict(),
  72. "features_numeric": NUMERIC, "features_bool": BOOL,
  73. "median_impute": {c: float(pd.to_numeric(df[c], errors="coerce")
  74. .median()) for c in NUMERIC},
  75. "notes": "risk = 100 * sigmoid(b0 + sum(c*x)); bools: 1=True, "
  76. "0=False, 0.5=unknown; numeric missing -> median "
  77. "+ missing indicator."}
  78. import json
  79. with open(MODEL_OUT, "w") as f:
  80. json.dump(out, f, indent=2)
  81. print(f"\nSaved -> {MODEL_OUT}")
  82. if __name__ == "__main__":
  83. main()