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From:	terra AT diku DOT dk (Morten Welinder)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: djgpp2 and TBAV
Date:	26 Aug 1995 05:12:58 GMT
Organization:	Department of Computer Science, U of Copenhagen
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Chi Hoang <choang AT freenet DOT calgary DOT ab DOT ca> writes:

>well, this is what TBAV says on all djgpp2 programs:
> Heuristic flags: c!?ZK AT i
> c  No checksum / recovery information (Anti-Vir.Dat) available. 

Well, that's for sure not our fault!  :-)


> !  Invalid opcode (non-8088 instructions) or out-of-range branch. 

We _need_ 386 instructions.  Is that what it complains about?


> ?  Inconsistent exe-header.  Might be a virus but can also be a bug. 

Hmm.  DJ, Charles: any ideas?


> Z  EXE/COM determination.  The program tries to check whether a file
>    is a COM or EXE file.  Viruses need to do this to infect a program. 

It's wrong here.  However, there is code in there to add ".EXE" to a
file name.  Is that what it complains about?



> K  Unusual stack.  The program has a suspicious stack or an odd stack. 

The stack is not very big and accurs in the middle.   I would think
that is what is detected.



> @  Encountered instructions which are not likely to be generated by
>    an assembler, but by some code generator like a polymorphic virus. 

Two things: djasm doesn't generate the same bit patterns as [mt]asm
would have done, and the code is optimized by hand for size.



> i  Additional data found at end of file. Probably internal overlay. 

Right, and what's wrong with that?





I say ship a compiled program and the source for the stub off to the
author of TBAV.  Have him _fix_ his program, or tell us what do to
differently.

Morten

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