cvssrust 1.1.0

Rust implementation of the Common Vulnerability Scoring System (v2 / v3.0 / v3.1)
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199

//! CVSS v3 scores implementation

use super::{base, env, MinorVersion, V3Vector};
use crate::common::{CVSSScore, NumValue, Optional, Score};

impl CVSSScore for V3Vector {
    fn impact_score(&self) -> Score {
        let scope_changed = self.scope == base::Scope::Changed;
        let iss = 1.0
            - ((1.0 - self.confidentiality.num_value())
                * (1.0 - self.integrity.num_value())
                * (1.0 - self.availability.num_value()));
        let impact = if scope_changed {
            7.52 * (iss - 0.029) - 3.25 * (iss - 0.02).powf(15.0)
        } else {
            6.42 * iss
        };
        Score::from(impact)
    }

    fn expoitability_score(&self) -> Score {
        Score::from(
            8.22 * self.attack_vector.num_value()
                * self.attack_complexity.num_value()
                * self
                    .privileges_required
                    .num_value_scoped(self.scope == base::Scope::Changed)
                * self.user_interaction.num_value(),
        )
    }

    fn base_score(&self) -> Score {
        let impact = self.impact_score().value();
        let expoitability = self.expoitability_score().value();
        let scope_changed = self.scope == base::Scope::Changed;
        let score = if impact <= 0.0 {
            0.0
        } else if scope_changed {
            (1.08 * (impact + expoitability)).min(10.0)
        } else {
            (impact + expoitability).min(10.0)
        };
        Score::from(if self.minor_version == MinorVersion::V1 {
            roundup_3_1(score)
        } else {
            roundup_3_0(score)
        })
    }

    /// TemporalScore =  Roundup (
    /// BaseScore × ExploitCodeMaturity × RemediationLevel × ReportConfidence)
    fn temporal_score(&self) -> Score {
        let score = self.base_score().value()
            * self.exploit_code_maturity.num_value()
            * self.remediation_level.num_value()
            * self.report_confidence.num_value();
        Score::from(if self.minor_version == MinorVersion::V1 {
            roundup_3_1(score)
        } else {
            roundup_3_0(score)
        })
    }

    fn environmental_score(&self) -> Score {
        let modified_impact = self.modified_impact_score().value();
        let modified_exploitability = self.modified_exploitability_score().value();
        if modified_impact == 0.0 {
            return Score::from(0.0);
        }
        let roundup = match self.minor_version {
            MinorVersion::V1 => roundup_3_1,
            MinorVersion::V0 => roundup_3_0,
        };
        let score = if self.modified_scope_changed() {
            roundup((1.08 * (modified_impact + modified_exploitability)).min(10.0))
                * self.exploit_code_maturity.num_value()
                * self.remediation_level.num_value()
                * self.report_confidence.num_value()
        } else {
            roundup((modified_impact + modified_exploitability).min(10.0))
                * self.exploit_code_maturity.num_value()
                * self.remediation_level.num_value()
                * self.report_confidence.num_value()
        };
        Score::from(roundup(score))
    }
}

impl V3Vector {
    fn modified_scope_changed(&self) -> bool {
        if self.modified_scope == env::ModifiedScope::NotDefined {
            self.scope == base::Scope::Changed
        } else {
            self.modified_scope == env::ModifiedScope::Changed
        }
    }

    /// Calculate Modified Impact SubScore
    pub fn modified_impact_subscore(&self) -> Score {
        let mod_conf = if !self.modified_confidentiality.is_undefined() {
            self.modified_confidentiality.num_value()
        } else {
            self.confidentiality.num_value()
        };
        let mod_int = if !self.modified_integrity.is_undefined() {
            self.modified_integrity.num_value()
        } else {
            self.integrity.num_value()
        };
        let mod_avail = if !self.modified_availability.is_undefined() {
            self.modified_availability.num_value()
        } else {
            self.availability.num_value()
        };
        let miss = 1.0
            - (1.0 - self.confidentiality_requirement.num_value() * mod_conf)
                * (1.0 - self.integrity_requirement.num_value() * mod_int)
                * (1.0 - self.availability_requirement.num_value() * mod_avail);
        Score::from(miss.min(0.915))
    }

    /// Calculate Modified Impact Score
    pub fn modified_impact_score(&self) -> Score {
        let scope_changed = self.modified_scope_changed();
        let miss = self.modified_impact_subscore().value();
        let p = match self.minor_version {
            MinorVersion::V1 => 13.0,
            MinorVersion::V0 => 15.0,
        };
        let impact = if scope_changed {
            7.52 * (miss - 0.029) - 3.25 * (miss * 0.9731 - 0.02).powf(p)
        } else {
            6.42 * miss
        };
        Score::from(impact)
    }

    /// Calculate Modified Exploitability Score
    pub fn modified_exploitability_score(&self) -> Score {
        let scope_changed = self.modified_scope_changed();
        let mod_av = if !self.modified_attack_vector.is_undefined() {
            self.modified_attack_vector.num_value()
        } else {
            self.attack_vector.num_value()
        };
        let mod_ac = if !self.modified_attack_complexity.is_undefined() {
            self.modified_attack_complexity.num_value()
        } else {
            self.attack_complexity.num_value()
        };
        let mod_pr = if !self.modified_privileges_required.is_undefined() {
            self.modified_privileges_required
                .num_value_scoped(scope_changed)
        } else {
            self.privileges_required.num_value_scoped(scope_changed)
        };
        let mod_ui = if !self.modified_user_interaction.is_undefined() {
            self.modified_user_interaction.num_value()
        } else {
            self.user_interaction.num_value()
        };
        Score::from(8.22 * mod_av * mod_ac * mod_pr * mod_ui)
    }
}

/// https://www.first.org/cvss/specification-document#Appendix-A---Floating-Point-Rounding
fn roundup_3_1(input: f64) -> f64 {
    let int_input = (input * 100_000.0) as u64;

    if int_input % 10_000 == 0 {
        int_input as f64 / 100_000.0
    } else {
        (((int_input / 10_000) as f64).floor() + 1.0) / 10.0
    }
}

/// https://www.first.org/cvss/v3.0/use-design
fn roundup_3_0(input: f64) -> f64 {
    (input * 10.0).ceil() / 10.0
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_roundup_3_1() {
        assert_eq!(roundup_3_1(4.0), 4.0);
        assert_eq!(roundup_3_1(4.02), 4.1);
        assert_eq!(roundup_3_1(4.07), 4.1);
    }

    #[test]
    fn test_roundup_3_0() {
        assert_eq!(roundup_3_0(4.0), 4.0);
        assert_eq!(roundup_3_0(4.02), 4.1);
        assert_eq!(roundup_3_0(4.07), 4.1);
    }
}