libmwemu 0.24.1

x86 32/64bits and system internals emulator, for securely emulating malware and other stuff.
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
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267

//! Tests for the FNSAVE and extended FNOP instructions.
//!
//! FNSAVE - Store x87 FPU State (non-waiting)
//! Extended FNOP - Extended NOP operations
//!
//! FNSAVE saves the entire FPU state to a 94 or 108 byte memory area,
//! then reinitializes the FPU. The instruction does not check for 
//! unmasked floating-point exceptions.
//!
//! Opcodes:
//! - FNSAVE: DD /6
//! - FNOP: D9 D0
//!
//! Reference: /Users/int/dev/rax/docs/fnsave.txt, /Users/int/dev/rax/docs/fnop.txt

use crate::*;
const DATA_ADDR: u64 = 0x7000;

fn write_u16(mem: u64, addr: u64, val: u16) {
    let mut emu = emu64();    emu.maps.write_bytes_slice(addr, &val.to_le_bytes());
}

fn read_u16(mem: u64, addr: u64) -> u16 {
    let emu = emu64();    let mut buf = [0u8; 2];
    emu.maps.read_bytes_buff(&mut buf, addr);
    u16::from_le_bytes(buf)
}

fn write_f64(mem: u64, addr: u64, val: f64) {
    let mut emu = emu64();    emu.maps.write_bytes_slice(addr, &val.to_le_bytes());
}

fn read_f64(mem: u64, addr: u64) -> f64 {
    let emu = emu64();    let mut buf = [0u8; 8];
    emu.maps.read_bytes_buff(&mut buf, addr);
    f64::from_le_bytes(buf)
}

// FNSAVE tests
#[test]
fn test_fnsave_basic() {
    let mut emu = emu64();    let code = [
        0xDD, 0x34, 0x25, 0x00, 0x20, 0x00, 0x00,  // FNSAVE [0x2000]
        0xF4,                                        // HLT
    ];
    emu.load_code_bytes(&code);
    emu.run(None).unwrap();
    let fcw = emu.maps.read_word(0x2000).unwrap();
    assert!(fcw < 0xFFFF);
}

#[test]
fn test_fnsave_with_data() {
    let mut emu = emu64();    let code = [
        0xDD, 0x04, 0x25, 0x00, 0x20, 0x00, 0x00,  // FLD qword [0x2000]
        0xDD, 0x34, 0x25, 0x00, 0x30, 0x00, 0x00,  // FNSAVE [0x3000]
        0xF4,                                        // HLT
    ];
    emu.load_code_bytes(&code);
    emu.maps.write_f64(0x2000, 1.5);
    emu.run(None).unwrap();
    let fcw = emu.maps.read_word(0x3000).unwrap();
    assert!(fcw < 0xFFFF);
}

#[test]
fn test_fnsave_reinitializes() {
    let mut emu = emu64();    let code = [
        0xDD, 0x04, 0x25, 0x00, 0x20, 0x00, 0x00,  // FLD qword [0x2000]
        0xDD, 0x34, 0x25, 0x00, 0x30, 0x00, 0x00,  // FNSAVE [0x3000]
        0xD9, 0xE8,                                  // FLD1 (should work on empty stack)
        0xDD, 0x1C, 0x25, 0x00, 0x40, 0x00, 0x00,  // FSTP qword [0x4000]
        0xF4,                                        // HLT
    ];
    emu.load_code_bytes(&code);
    emu.maps.write_f64(0x2000, 2.5);
    emu.run(None).unwrap();
    let result = emu.maps.read_f64(0x4000).unwrap();
    assert_eq!(result, 1.0);
}

// FNOP tests
#[test]
fn test_fnop_basic() {
    let mut emu = emu64();    let code = [
        0xD9, 0xD0,  // FNOP
        0xF4,        // HLT
    ];
    emu.load_code_bytes(&code);
    emu.run(None).unwrap();
}

#[test]
fn test_fnop_preserves_stack() {
    let mut emu = emu64();    let code = [
        0xDD, 0x04, 0x25, 0x00, 0x20, 0x00, 0x00,  // FLD qword [0x2000]
        0xD9, 0xD0,                                  // FNOP
        0xDD, 0x1C, 0x25, 0x00, 0x30, 0x00, 0x00,  // FSTP qword [0x3000]
        0xF4,                                        // HLT
    ];
    emu.load_code_bytes(&code);
    emu.maps.write_f64(0x2000, 3.14);
    emu.run(None).unwrap();
    let result = emu.maps.read_f64(0x3000).unwrap();
    assert_eq!(result, 3.14);
}

#[test]
fn test_fnop_sequence() {
    let mut emu = emu64();    let code = [
        0xD9, 0xD0,  // FNOP
        0xD9, 0xD0,  // FNOP
        0xD9, 0xD0,  // FNOP
        0xF4,        // HLT
    ];
    emu.load_code_bytes(&code);
    emu.run(None).unwrap();
}

// Additional FNSAVE tests
#[test]
fn test_fnsave_multiple_values() {
    let mut emu = emu64();    let code = [
        0xDD, 0x04, 0x25, 0x00, 0x20, 0x00, 0x00,  // FLD qword [0x2000]
        0xDD, 0x04, 0x25, 0x08, 0x20, 0x00, 0x00,  // FLD qword [0x2008]
        0xDD, 0x34, 0x25, 0x00, 0x30, 0x00, 0x00,  // FNSAVE [0x3000]
        0xF4,                                        // HLT
    ];
    emu.load_code_bytes(&code);
    emu.maps.write_f64(0x2000, 1.0);
    emu.maps.write_f64(0x2008, 2.0);
    emu.run(None).unwrap();
}

#[test]
fn test_fnop_with_arithmetic() {
    let mut emu = emu64();    let code = [
        0xDD, 0x04, 0x25, 0x00, 0x20, 0x00, 0x00,  // FLD qword [0x2000]
        0xD9, 0xD0,                                  // FNOP
        0xDD, 0x04, 0x25, 0x08, 0x20, 0x00, 0x00,  // FLD qword [0x2008]
        0xD9, 0xD0,                                  // FNOP
        0xDE, 0xC1,                                  // FADDP
        0xDD, 0x1C, 0x25, 0x00, 0x30, 0x00, 0x00,  // FSTP qword [0x3000]
        0xF4,                                        // HLT
    ];
    emu.load_code_bytes(&code);
    emu.maps.write_f64(0x2000, 1.0);
    emu.maps.write_f64(0x2008, 2.0);
    emu.run(None).unwrap();
    let result = emu.maps.read_f64(0x3000).unwrap();
    assert_eq!(result, 3.0);
}

#[test]
fn test_fnsave_after_arithmetic() {
    let mut emu = emu64();    let code = [
        0xD9, 0xE8,                                  // FLD1
        0xD9, 0xE8,                                  // FLD1
        0xDE, 0xC1,                                  // FADDP
        0xDD, 0x34, 0x25, 0x00, 0x30, 0x00, 0x00,  // FNSAVE [0x3000]
        0xF4,                                        // HLT
    ];
    emu.load_code_bytes(&code);
    emu.run(None).unwrap();
}

// More comprehensive tests (30+ total)
macro_rules! fnsave_test {
    ($name:ident, $val:expr) => {
        #[test]
        fn $name() {
    let mut emu = emu64();            let code = [
                0xDD, 0x04, 0x25, 0x00, 0x20, 0x00, 0x00,
                0xDD, 0x34, 0x25, 0x00, 0x30, 0x00, 0x00,
                0xF4,
            ];
            emu.load_code_bytes(&code);
            emu.maps.write_f64(0x2000, $val);
    emu.run(None).unwrap();
        }
    };
}

fnsave_test!(test_fnsave_inf, f64::INFINITY);
fnsave_test!(test_fnsave_neg_inf, f64::NEG_INFINITY);
fnsave_test!(test_fnsave_zero, 0.0);
fnsave_test!(test_fnsave_neg_zero, -0.0);
fnsave_test!(test_fnsave_one, 1.0);
fnsave_test!(test_fnsave_neg_one, -1.0);
fnsave_test!(test_fnsave_large, 1e100);
fnsave_test!(test_fnsave_small, 1e-100);
fnsave_test!(test_fnsave_pi, std::f64::consts::PI);
fnsave_test!(test_fnsave_e, std::f64::consts::E);

macro_rules! fnop_test {
    ($name:ident, $val:expr) => {
        #[test]
        fn $name() {
    let mut emu = emu64();            let code = [
                0xDD, 0x04, 0x25, 0x00, 0x20, 0x00, 0x00,
                0xD9, 0xD0,
                0xDD, 0x1C, 0x25, 0x00, 0x30, 0x00, 0x00,
                0xF4,
            ];
            emu.load_code_bytes(&code);
            emu.maps.write_f64(0x2000, $val);
    emu.run(None).unwrap();
            let result = emu.maps.read_f64(0x3000).unwrap();
            assert_eq!(result, $val);
        }
    };
}

fnop_test!(test_fnop_inf, f64::INFINITY);
fnop_test!(test_fnop_neg_inf, f64::NEG_INFINITY);
fnop_test!(test_fnop_zero, 0.0);
fnop_test!(test_fnop_large, 1e200);
fnop_test!(test_fnop_small, 1e-200);
fnop_test!(test_fnop_negative, -42.5);
fnop_test!(test_fnop_positive, 42.5);
fnop_test!(test_fnop_frac, 0.125);
fnop_test!(test_fnop_max, f64::MAX);
fnop_test!(test_fnop_min, f64::MIN);

#[test]
fn test_fnsave_stack_depth() {
    let mut emu = emu64();    let code = [
        0xD9, 0xE8, 0xD9, 0xE8, 0xD9, 0xE8, 0xD9, 0xE8,
        0xDD, 0x34, 0x25, 0x00, 0x30, 0x00, 0x00,
        0xF4,
    ];
    emu.load_code_bytes(&code);
    emu.run(None).unwrap();
}

#[test]
fn test_fnop_doesnt_affect_flags() {
    let mut emu = emu64();    let code = [
        0xDD, 0x04, 0x25, 0x00, 0x20, 0x00, 0x00,
        0xDD, 0x04, 0x25, 0x08, 0x20, 0x00, 0x00,
        0xD8, 0xD1,  // FCOM
        0xD9, 0xD0,  // FNOP
        0xDD, 0xD8,
        0xDD, 0xD8,
        0xF4,
    ];
    emu.load_code_bytes(&code);
    emu.maps.write_f64(0x2000, 1.0);
    emu.maps.write_f64(0x2008, 2.0);
    emu.run(None).unwrap();
}

#[test]
fn test_fnsave_consistency() {
    let mut emu = emu64();    let code = [
        0xD9, 0xE8,
        0xDD, 0x34, 0x25, 0x00, 0x30, 0x00, 0x00,
        0xD9, 0xE8,
        0xDD, 0x34, 0x25, 0x00, 0x31, 0x00, 0x00,
        0xF4,
    ];
    emu.load_code_bytes(&code);
    emu.run(None).unwrap();
    let fcw1 = emu.maps.read_word(0x3000).unwrap();
    let fcw2 = emu.maps.read_word(0x3100).unwrap();
    assert_eq!(fcw1, fcw2);
}