Fix module audit findings (#850)

* Fix module audit findings

* Always parse paired tombstones

tests/ios_backup/test_sqlite_handling.py

@@ -0,0 +1,85 @@
+# Mobile Verification Toolkit (MVT)
+# Copyright (c) 2021-2023 The MVT Authors.
+# Use of this software is governed by the MVT License 1.1 that can be found at
+#   https://license.mvt.re/1.1/
+
+import hashlib
+import os
+import plistlib
+import shutil
+import sqlite3
+
+from mvt.ios.modules.base import IOSExtraction
+from mvt.ios.modules.fs.analytics import Analytics
+
+
+def _sha256(path):
+    return hashlib.sha256(path.read_bytes()).hexdigest()
+
+
+def test_open_sqlite_reads_wal_without_modifying_evidence(tmp_path):
+    live_path = tmp_path / "live.db"
+    evidence_path = tmp_path / "evidence.db"
+    conn = sqlite3.connect(live_path)
+    conn.execute("PRAGMA journal_mode=WAL;")
+    conn.execute("PRAGMA wal_autocheckpoint=0;")
+    conn.execute("CREATE TABLE records (value TEXT);")
+    conn.commit()
+    conn.execute("INSERT INTO records VALUES ('from wal');")
+    conn.commit()
+
+    shutil.copy2(live_path, evidence_path)
+    shutil.copy2(str(live_path) + "-wal", str(evidence_path) + "-wal")
+    conn.close()
+
+    evidence_hash = _sha256(evidence_path)
+    wal_hash = _sha256(tmp_path / "evidence.db-wal")
+    module = IOSExtraction(file_path=str(evidence_path))
+    read_conn = module._open_sqlite_db(str(evidence_path))
+    rows = read_conn.execute("SELECT value FROM records;").fetchall()
+    read_conn.close()
+
+    assert rows == [("from wal",)]
+    assert _sha256(evidence_path) == evidence_hash
+    assert _sha256(tmp_path / "evidence.db-wal") == wal_hash
+    assert not os.path.exists(str(evidence_path) + "-shm")
+
+
+def test_recovery_preserves_source_database(tmp_path):
+    database_path = tmp_path / "source.db"
+    conn = sqlite3.connect(database_path)
+    conn.execute("CREATE TABLE records (value TEXT);")
+    conn.execute("INSERT INTO records VALUES ('preserved');")
+    conn.commit()
+    conn.close()
+    source_hash = _sha256(database_path)
+
+    module = IOSExtraction(file_path=str(database_path))
+    module._recover_sqlite_db_if_needed(str(database_path), forced=True)
+    recovered_conn = module._open_sqlite_db(str(database_path))
+    rows = recovered_conn.execute("SELECT value FROM records;").fetchall()
+    recovered_conn.close()
+
+    assert rows == [("preserved",)]
+    assert _sha256(database_path) == source_hash
+    assert not os.path.exists(str(database_path) + ".bak")
+
+
+def test_analytics_skips_empty_rows_and_continues(tmp_path):
+    database_path = tmp_path / "analytics.db"
+    conn = sqlite3.connect(database_path)
+    for table in ("hard_failures", "soft_failures", "all_events"):
+        conn.execute(f"CREATE TABLE {table} (timestamp REAL, data BLOB);")
+    conn.execute("INSERT INTO hard_failures VALUES (NULL, NULL);")
+    conn.execute(
+        "INSERT INTO soft_failures VALUES (?, ?);",
+        (1.0, plistlib.dumps({"event": "valid"})),
+    )
+    conn.commit()
+    conn.close()
+
+    module = Analytics(file_path=str(database_path))
+    module._extract_analytics_data()
+
+    assert len(module.results) == 1
+    assert module.results[0]["event"] == "valid"