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Re: What Thinkest Thou Of LO Donate Banner?

Cross-posted to 2 groups.

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On Sun, 23 Nov 2025 03:19:35 -0000 (UTC)
Gremlin <nobody@haph.org> wrote:

> >> You can't depend on a files extension to actually be what the file
> >> is.  
> > 
> > Once upon a time you could, in MS-land, but Win95 and Windows
> > Explorer hopelessly muddied the waters on this in trying to make
> > file-type handling semi-transparent :/  
> 
> Hmm. I don't remember a time in MS days from DOS to Windows that the
> file extension could absolutely be trusted. Even under the days of
> DOS, the extension didn't really matter if you did this:
> HITHERE.TXT for the example is really an .exe file. 
> 
> ; Assume a command string "HITHERE.TXT" is in memory
> ; and a valid parameter block is also set up.
> 
> MOV AH, 4Bh       ; EXEC - Execute Program
> MOV AL, 00h       ; Load and execute
> MOV DX, OFFSET command_string ; DS:DX points to command string
> MOV BX, OFFSET param_block    ; ES:BX points to parameter block
> INT 21h
> 
> You couldn't type hithere.txt from a command prompt and it execute,
> sure. But, you could do something like the above in asm/another
> language of choice and it would, if it was an executable.

Interesting - I'm curious how common that actually was back in the day,
though? I don't recall a lot of DOS applications that I used chaining
from one EXE to another, unless you were really into launcher-menu type
utilities; most of what I remember was single EXEs for the main program
plus accessory EXEs for configuration (i.e. the inevitable SOUNDSET.EXE
and its ilk,) and transfer of control was usually mediated by a *.BAT
launcher script.

(Although if COMMAND.COM invokes that mechanism itself in interpreting
batch scripts, that'd certainly leave it vulnerable; no idea if that's
the case or not.)

> If it starts with MZ for example, you should be scanning it - because
> that's a well known marker for an executable file. Just as an
> example. .com files were a little trickier because they didn't
> officially have a header.

Yeah, it certainly doesn't hurt to sniff for a valid header if you're
already looking at the file.

> Windows95 and above encouraged users to trust the file extension.
> That the extension was what the file really was. This resulted some
> in people being a little cheeky and having a bit of fun with it. such
> as openme.txt.exe. You'd see openme.txt and not the actual extension.
> So one double click for many users later and you might have had
> yourself a problem. In order to see the actual extension, you would
> have to turn hide extensions (the default setting) off.

Yes - this was an absolute misfeature in Win9x, and one that was pretty
plainly a "look, we can *so* be MacOS!" on MS's part to boot. Caused no
*end* of shenanigans over the years, it has... :/

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Re: What Thinkest Thou Of LO Donate Banner? Gremlin <nobody@haph.org> - 2025-11-20 22:23 +0000
  Re: What Thinkest Thou Of LO Donate Banner? John Ames <commodorejohn@gmail.com> - 2025-11-20 14:59 -0800
    Re: What Thinkest Thou Of LO Donate Banner? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-20 23:54 +0000
      Re: What Thinkest Thou Of LO Donate Banner? Brock McNuggets <brock.mcnuggets@gmail.com> - 2025-11-21 00:44 +0000
      Re: What Thinkest Thou Of LO Donate Banner? John Ames <commodorejohn@gmail.com> - 2025-11-21 14:33 -0800
        Re: What Thinkest Thou Of LO Donate Banner? Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2025-11-22 00:16 +0000
          Re: What Thinkest Thou Of LO Donate Banner? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-22 00:20 +0000
            Re: What Thinkest Thou Of LO Donate Banner? rbowman <bowman@montana.com> - 2025-11-22 03:20 +0000
              Re: What Thinkest Thou Of LO Donate Banner? pothead <pothead@snakebite.com> - 2025-11-22 14:17 +0000
                Re: What Thinkest Thou Of LO Donate Banner? Nuno Silva <nunojsilva@invalid.invalid> - 2025-11-22 14:39 +0000
                Re: What Thinkest Thou Of LO Donate Banner? rbowman <bowman@montana.com> - 2025-11-22 20:08 +0000
                Re: What Thinkest Thou Of LO Donate Banner? tom nossen <news@nossen.org> - 2025-11-26 22:07 +0100
                Re: What Thinkest Thou Of LO Donate Banner? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-26 21:50 +0000
                Re: What Thinkest Thou Of LO Donate Banner? tom nossen <news@nossen.org> - 2025-11-27 12:18 +0100
                Re: What Thinkest Thou Of LO Donate Banner? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-27 21:26 +0000
                Re: What Thinkest Thou Of LO Donate Banner? Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2025-11-22 18:56 +0000
          Re: What Thinkest Thou Of LO Donate Banner? John Ames <commodorejohn@gmail.com> - 2025-11-24 09:06 -0800
            Re: What Thinkest Thou Of LO Donate Banner? "Joel W. Crump" <joelcrump@gmail.com> - 2025-11-24 12:10 -0500
              Re: What Thinkest Thou Of LO Donate Banner? John Ames <commodorejohn@gmail.com> - 2025-11-24 09:29 -0800
            Re: What Thinkest Thou Of LO Donate Banner? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-24 23:15 +0000
              Re: What Thinkest Thou Of LO Donate Banner? John Ames <commodorejohn@gmail.com> - 2025-11-24 15:35 -0800
              Re: What Thinkest Thou Of LO Donate Banner? rbowman <bowman@montana.com> - 2025-11-25 00:21 +0000
    Re: What Thinkest Thou Of LO Donate Banner? Gremlin <nobody@haph.org> - 2025-11-23 03:19 +0000
      Re: What Thinkest Thou Of LO Donate Banner? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-23 05:20 +0000
      Re: What Thinkest Thou Of LO Donate Banner? John Ames <commodorejohn@gmail.com> - 2025-11-24 09:26 -0800
        Re: What Thinkest Thou Of LO Donate Banner? Brock McNuggets <brock.mcnuggets@gmail.com> - 2025-11-24 18:27 +0000
        Re: What Thinkest Thou Of LO Donate Banner? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-24 23:23 +0000
        Re: What Thinkest Thou Of LO Donate Banner? Gremlin <nobody@haph.org> - 2025-12-02 20:13 +0000
  Re: What Thinkest Thou Of LO Donate Banner? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-20 23:01 +0000
  Re: What Thinkest Thou Of LO Donate Banner? Nuno Silva <nunojsilva@invalid.invalid> - 2025-11-21 09:58 +0000
    Re: What Thinkest Thou Of LO Donate Banner? Gremlin <nobody@haph.org> - 2025-11-23 03:19 +0000
      Re: What Thinkest Thou Of LO Donate Banner? Lawrence D’Oliveiro <ldo@nz.invalid> - 2025-11-23 05:21 +0000
        Re: What Thinkest Thou Of LO Donate Banner? Brock McNuggets <brock.mcnuggets@gmail.com> - 2025-11-23 19:01 +0000
        Re: What Thinkest Thou Of LO Donate Banner? Gremlin <nobody@haph.org> - 2025-11-23 23:23 +0000
          Re: What Thinkest Thou Of LO Donate Banner? Nuno Silva <nunojsilva@invalid.invalid> - 2025-11-23 23:41 +0000
          Re: What Thinkest Thou Of LO Donate Banner? Brock McNuggets <brock.mcnuggets@gmail.com> - 2025-11-24 00:39 +0000
            Re: What Thinkest Thou Of LO Donate Banner? c186282 <c186282@nnada.net> - 2025-11-23 23:46 -0500
              Re: What Thinkest Thou Of LO Donate Banner? Brock McNuggets <brock.mcnuggets@gmail.com> - 2025-11-24 15:45 +0000
                Re: What Thinkest Thou Of LO Donate Banner? "Carlos E.R." <robin_listas@es.invalid> - 2025-11-24 20:59 +0100
                Re: What Thinkest Thou Of LO Donate Banner? ALB <alb@lupinedb.org> - 2025-11-25 19:38 -0500
                Re: What Thinkest Thou Of LO Donate Banner? The Natural Philosopher <tnp@invalid.invalid> - 2025-11-26 13:35 +0000
                Re: What Thinkest Thou Of LO Donate Banner? Brock McNuggets <brock.mcnuggets@gmail.com> - 2025-11-26 15:12 +0000

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