Fix missing condition in convert_cvssv2_vector_to_cvssv3_vector function

Test function with nvd_cvss.csv data
Remove function from severity_systems.py
Rename file to cvss2to3.py
Add download_url fof severity_systems.py.ABOUT
Fix notes
Test with nvd severity data
Move the cvssv2_converter.py to serverity_systems.py
Give credit to Marc Ruef
Fix missing parts in the vector
Add some tests
Edit CI,  II , AI to C , I,  A
Convert CVSSv2 into CVSSv3

Signed-off-by: ziadhany <ziadhany2016@gmail.com>

Author: ziadhany

vulnerabilities/cvss2to3.py

@@ -0,0 +1,123 @@
+from cvss import CVSS2
+
+
+def convert_cvssv2_vector_to_cvssv3_vector(cvssv2_vector):
+    """
+    Returns the CVSSv3 vector
+    >>> cvssv2_vector = "AV:L/AC:L/Au:M/C:N/I:P/A:C/E:U/RL:W/RC:ND/CDP:L/TD:H/CR:ND/IR:ND/AR:M"
+    >>> cvssv3_vector = convert_cvssv2_vector_to_cvssv3_vector(cvssv2_vector)
+    >>> assert cvssv3_vector == 'CVSS:3.0/AV:L/UI:N/AC:L/PR:H/C:N/I:L/A:H/S:C/E:U/RL:W/RC:X'
+    """
+    cvss2_metrics = CVSS2(cvssv2_vector).metrics
+    cvss3_metrics = {}
+
+    # AV (P is new)
+    if cvss2_metrics.get("AV") == "L":
+        # L => (L|P) (usually L)
+        cvss3_metrics["AV"] = "L"
+
+    elif cvss2_metrics.get("AV") == "A":
+        # A => A
+        cvss3_metrics["AV"] = "A"
+
+    elif cvss2_metrics.get("AV") == "N":
+        # N => N
+        cvss3_metrics["AV"] = "N"
+
+    # AC split into AC and UI
+    cvss3_metrics["UI"] = "R"
+    if cvss2_metrics["AC"] == "L":
+        cvss3_metrics["AC"] = "L"
+        cvss3_metrics["UI"] = "N"
+
+    elif cvss2_metrics["AC"] == "M":
+        cvss3_metrics["AC"] = "L"
+
+    elif cvss2_metrics["AC"] == "H":
+        cvss3_metrics["AC"] = "H"
+
+    # Au => PR (needs manual optimization)
+    if cvss2_metrics.get("Au") == "N":
+        # N => N
+        cvss3_metrics["PR"] = "N"
+
+    elif cvss2_metrics.get("Au") == "S":
+        # S => (L|H) (usually L)
+        cvss3_metrics["PR"] = "L"
+
+    elif cvss2_metrics.get("Au") == "M":
+        # M => (H|L) (sometimes H)
+        cvss3_metrics["PR"] = "H"
+
+    # C, I and A
+    # C => H , P => L, N => N
+    for key in ["C", "I", "A"]:
+        if cvss2_metrics.get(key) == "N":
+            cvss3_metrics[key] = "N"
+        elif cvss2_metrics.get(key) == "P":
+            cvss3_metrics[key] = "H"
+        elif cvss2_metrics.get(key) == "C":
+            cvss3_metrics[key] = "H"
+
+    # C:C/I:C/A:C derived by S:C
+    if (
+        cvss2_metrics.get("C") == "C"
+        and cvss2_metrics.get("I") == "C"
+        and cvss2_metrics.get("A") == "C"
+    ):
+        cvss3_metrics["S"] = "C"
+    else:
+        cvss3_metrics["S"] = "U"
+
+    # E
+    # ND => X , U => U, POC => P, F => F, H => H
+    if cvss2_metrics.get("E") == "POC":
+        cvss3_metrics["E"] = "P"
+
+    elif cvss2_metrics.get("E") == "ND":
+        cvss3_metrics["E"] = "X"
+
+    elif cvss2_metrics.get("E") == "F":
+        cvss3_metrics["E"] = "F"
+
+    elif cvss2_metrics.get("E") == "H":
+        cvss3_metrics["E"] = "H"
+
+    elif cvss2_metrics.get("E") == "U":
+        cvss3_metrics["E"] = "U"
+
+    # RL
+    # ND => X, OF => O, TF => T, W => W, U => U
+    if cvss2_metrics.get("RL") == "ND":
+        cvss3_metrics["RL"] = "X"
+
+    elif cvss2_metrics.get("RL") == "OF":
+        cvss3_metrics["RL"] = "X"
+
+    elif cvss2_metrics.get("RL") == "TF":
+        cvss3_metrics["RL"] = "P"
+
+    elif cvss2_metrics.get("RL") == "W":
+        cvss3_metrics["RL"] = "W"
+
+    elif cvss2_metrics.get("RL") == "U":
+        cvss3_metrics["RL"] = "U"
+
+    # RC
+    # C = > C, UR = > R, UC = > U, ND = > X
+    if cvss2_metrics.get("RC") == "C":
+        cvss3_metrics["RC"] = "C"
+
+    elif cvss2_metrics.get("RC") == "UR":
+        cvss3_metrics["RC"] = "R"
+
+    elif cvss2_metrics.get("RC") == "UC":
+        cvss3_metrics["RC"] = "U"
+
+    elif cvss2_metrics.get("RC") == "ND":
+        cvss3_metrics["RC"] = "X"
+
+    cvssv3_vector = ""
+    for k, v in cvss3_metrics.items():
+        cvssv3_vector += f"/{k}:{v}"
+    return "CVSS:3.0/" + cvssv3_vector[1::]

vulnerabilities/cvss2to3.py.ABOUT

@@ -0,0 +1,6 @@
+about_resource: cvss2to3.py
+author: Marc Ruef @marcruef
+notes: convert_cvssv2_vector_to_cvssv3_vector function was written using Marc Ruef's answer from stackexchange question
+license_expression: cc-by-sa-3.0
+license_file: cvss2to3.py.LICENSE
+download_url: https://security.stackexchange.com/questions/127335/how-to-convert-risk-scores-cvssv1-cvssv2-cvssv3-owasp-risk-severity