memscan 0.1.0

A pattern-based memory scanner
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

use rayon::prelude::*;
use std::str::FromStr;
use subslice_index::subslice_index;

/// A memory pattern. Wildcards are represented in raw buffers
/// as null bytes. Must not be empty
pub struct Pattern {
    buf: Vec<u8>,
}

impl Pattern {
    /// Tests if a pattern matches a slice of bytes exactly
    ///
    /// # Arguments
    ///
    /// `buf`: The slice of bytes
    pub fn matches(&self, buf: &[u8]) -> bool {
        self.buf
            .par_iter()
            .zip(buf.par_iter())
            .all(|(&pattern_byte, &buffer_byte)| {
                pattern_byte == 0x00 || pattern_byte == buffer_byte
            })
    }
}

impl From<&[u8]> for Pattern {
    fn from(buf: &[u8]) -> Pattern {
        Pattern {
            buf: Vec::from(buf),
        }
    }
}

/// This is not recommended, but is provided as a compatibility layer for
/// those who have signatures in IDA format, for example
impl FromStr for Pattern {
    type Err = usize;

    /// The index of the bad pattern character is returned
    fn from_str(buf_str: &str) -> Result<Pattern, Self::Err> {
        let mut buf = Vec::new();
        for byte_str in buf_str.split_ascii_whitespace() {
            if byte_str == "?" {
                buf.push(0x00);
            } else {
                match u8::from_str_radix(byte_str, 16) {
                    Ok(byte) => {
                        buf.push(byte);
                    }
                    Err(_) => return Err(subslice_index(buf_str.as_bytes(), byte_str.as_bytes())),
                };
            }
        }
        Ok(Pattern { buf })
    }
}

/// Finds a pattern in a buffer
///
/// # Arguments
///
/// `buf`: The buffer to search for the pattern in
/// `pattern`: The pattern to find. Must not be empty
pub fn find_pattern(buf: &[u8], pattern: Pattern) -> Vec<&[u8]> {
    buf.par_windows(pattern.buf.len())
        .filter(|&window| pattern.matches(window))
        .collect()
}

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

    #[test]
    #[should_panic]
    fn empty_pattern() {
        let buf = &[1, 2, 3];
        let pattern = Pattern::from(&[][..]);
        find_pattern(buf, pattern);
    }

    #[test]
    fn not_empty() {
        let buf = &[1, 2, 3];
        let pattern = Pattern::from(&[1, 2][..]);
        assert!(!find_pattern(buf, pattern).is_empty());
    }

    #[test]
    fn empty() {
        let buf = &[1, 2, 3];
        let pattern = Pattern::from(&[1, 3][..]);
        assert!(find_pattern(buf, pattern).is_empty());
    }

    #[test]
    fn simple_wildcard_not_empty() {
        let buf = &[1, 2, 3];
        let pattern = Pattern::from(&[1, 0x00, 3][..]);
        assert!(!find_pattern(buf, pattern).is_empty());
    }

    #[test]
    fn simple_wildcard_empty() {
        let buf = &[1, 2, 3];
        let pattern = Pattern::from(&[1, 0x00, 4][..]);
        assert!(find_pattern(buf, pattern).is_empty());
    }

    #[test]
    fn wildcard_start_not_empty() {
        let buf = &[1, 2, 3];
        let pattern = Pattern::from(&[0x00, 3][..]);
        assert!(!find_pattern(buf, pattern).is_empty());
    }

    #[test]
    fn wildcard_start_empty() {
        let buf = &[1, 2, 3];
        let pattern = Pattern::from(&[0x00, 1][..]);
        assert!(find_pattern(buf, pattern).is_empty());
    }

    #[test]
    fn wildcard_end_not_empty() {
        let buf = &[1, 2, 3];
        let pattern = Pattern::from(&[1, 2, 0x00][..]);
        assert!(!find_pattern(buf, pattern).is_empty());
    }

    #[test]
    fn wildcard_end_empty() {
        let buf = &[1, 2, 3];
        let pattern = Pattern::from(&[2, 3, 0x00][..]);
        assert!(find_pattern(buf, pattern).is_empty());
    }

    #[test]
    fn multi_match() {
        let buf = &[1, 2, 3, 4, 3, 2, 1, 2, 3];
        let pattern = Pattern::from(&[1, 2, 0x00][..]);
        assert_eq!(find_pattern(buf, pattern).len(), 2);
    }

    #[test]
    fn function_signature() {
        let buf = include_bytes!("..\\test\\crt.exe");
        let pattern = Pattern::from(
            &[
                0xe8, 0x00, 0x00, 0x00, 0x00, 0xe8, 0x00, 0x00, 0x00, 0x00, 0x48, 0x8b, 0xd8,
            ][..],
        );
        let result = find_pattern(buf, pattern);
        assert!(!result.is_empty());
        assert_eq!(
            result[0],
            &[0xe8, 0x1c, 0x04, 0x00, 0x00, 0xe8, 0xcb, 0x05, 0x00, 0x00, 0x48, 0x8b, 0xd8][..]
        );
        assert_eq!(subslice_index(buf, result[0]), 0x5bb);
    }
}