tailieunhanh - the giant black book of computer viruses phần 5

và hầu hết các kỹ thuật chúng tôi đã thảo luận cho trong chương cuối cùng thực hiện một virus OS / 2 cũng. Sự khác biệt chính giữa OS / 2 và Windows a) các dịch vụ gián đoạn cơ bản biến mất hoàn toàn, ngoại trừ trong một hộp DOS | An OS 2 Virus OS 2 programs are very similar to Windows programs and most of the techniques we discussed for Windows viruses in the last chapter carry over to an OS 2 virus as well. The main differences between OS 2 and Windows are a the underlying interrupt services disappear completely except in a DOS box and even then you don t get everything b the function names and calling conventions differ from Windows and c assembly language-level coding details are even more poorly documented than they are for Windows. It would seem the people who wrote OS 2 want you to program everything in C. OS 2 Memory Models In addition to the above differences OS 2 supports two completely different memory models for programs. One is called the segmented or 16 16 memory model because it uses 16 bit offsets and 16 bit selectors to access code and data. The other memory model is called the flat or 0 32 model. This model uses 32 bit offsets which can access up to 4 gigabytes of address space. That s the entire addressable memory for 80386 processors so segments aren t really necessary. Thus they re all set to zero. Programs in these two memory models are as different as COM and EXE files and completely different techniques are required to 262 The Giant Black Book of Computer Viruses infect them. We will examine a virus to infect segmented memory model programs here named Blue Lightening. A flat memory model virus is left as an exercise for the reader. OS 2 Programming Tools Although writing assembly language programs for OS 2 seems to be a black art it s no harder than doing it for Windows. You will need OS 2 compatible tools to do it though. For most programs you ll need an assembler which is OS 2 wise. The only one I m really aware of is MASM and up. Then you ll also need LINK . Both of these tools are distributed with IBM s Developer Connection kit which you ll probably want to get your hands on if you re serious about developing OS 2 programs. Unlike Windows OS 2 was .