  Whenever a bug occurs in a program, software developers assume that the code
is flawed, not the compiler. In fact, if compilers should be correct, they are
just normal software with their own bugs. Hard to find, errors in them have
significant impact, since it could result to vulnerabilities, especially when
they silently miscompile a critical application. Using assembly language to
write such software is quite common, especially when time constraint is
involved in such program.
  This paper exposes a bug found in Microsoft Macro Assembler (ml for short)
compiler, developed by Microsoft since 1981. This assembly has the
characteristics to get high level-like constructs and high level-like records
which help the developer to write assembly code. It is in the management of one
of this level-like construct the bug has been found.
  This study aims to show how a compiler-bug can be audited and possibly
corrected. For application developers, it shows that even old and mature
compilers can present bugs. For security researcher, it shows possibilities to
hide some unexpected behavior in software with a clear and officially non-bogus
code. It highlights opportunities for including stealth backdoors even in
open-source software.
