Discovery / credits: malvuln - (c) 2021  
Original source:  
Threat: Trojan:Win32/Alyak.B   
Vulnerability: Remote Stack Corruption  
Description: Read access violation results in stack corruption and crash. Specimen makes HTTP request for a plain text-file "1.txt" in the "images" directory Port 80.  
Point test machine gateway to a system you control and redirect DNS traffic for PoC.  
Send large payload of junk chars in server response for the requested "images/1.txt" file.  
Type: PE32  
MD5: 6547f34243104ba6e21154ad96b799a5  
Vuln ID: MVID-2021-0004  
Dropped files: AYLaunch.exe   
ASLR: False  
DEP: False  
Safe SEH: True  
Disclosure: 01/01/2021  
Memory Dump:  
0:000> .ecxr  
eax=0019c7c4 ebx=00000000 ecx=00000000 edx=6d6d6d6d esi=76e34f60 edi=00000000  
eip=6d6d6d6d esp=0019a3a4 ebp=6d6d6d6d iopl=0 nv up ei pl nz na pe nc  
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010206  
6d6d6d6d ?? ???  
0:000> .exr -1  
ExceptionAddress: 6d6d6d6d  
ExceptionCode: c0000005 (Access violation)  
ExceptionFlags: 00000000  
NumberParameters: 2  
Parameter[0]: 00000000  
Parameter[1]: 6d6d6d6d  
Attempt to read from address 6d6d6d6d  
dd 0019D3C4  
0:000> dd 0019D3C4  
0019d3c4 41414141 41414141 41414141 41414141  
0019d3d4 41414141 41414141 41414141 41414141  
0019d3e4 41414141 41414141 41414141 41414141  
0019d3f4 41414141 41414141 41414141 41414141  
0019d404 41414141 41414141 41414141 41414141  
python -c "print 'A'*60000" > 1.txt  
Start server.  
python -m http.server 80  
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