RE: [ok] [Full-Disclosure] RE: Unchecked buffer in mstask.dll

[Curt Purdy]

Dmitry Yu wrote:
> > Being curious, on Win2k, I copied cmd.exe (from
> winnt\system32) as xyz.pif;
> > then (right-click) Properties, Program crashes explorer. Is
> this related to
> > IconHandler, and is it exploitable?
>
> Disassembly window shows that there was an attempt to read dword
> at [EAX] (EAX=0). So at first glance this doesn't seem to be
> trivially
> exploitable, but I'm not a win32 expert, and intuition
> suggests that there
> must be a way.

One possible exploit is to simply place the file on your desktop.
explorer.exe goes to 100% cpu.

Curt Purdy CISSP, GSEC, MCSE+I, CNE, CCDA
Information Security Engineer
DP Solutions

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If you spend more on coffee than on IT security, you will be hacked.
What's more, you deserve to be hacked.
-- former White House cybersecurity adviser Richard Clarke

[Curt Purdy]

Nick FitzGerald wrote:
> > I'd say that's because you changed the filetype; pif files simply
> > contain information on how to handle a DOS executable; they aren't a
> > program themselves. All you did was make it get confused and kill
> > itself.
>
> Yeah, but how long is it now since we've been telling programmers
> "don't trust user-supplied data"?? (Hmmmm -- does it also fail on
> W2K3??)

No, in W2K3 you get "Cannot query the properties for this program. There may
not be enough memory available. blah blah" as opposed to 100% cpu in 2K.

Curt Purdy CISSP, GSEC, MCSE+I, CNE, CCDA
Information Security Engineer
DP Solutions

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If you spend more on coffee than on IT security, you will be hacked.
What's more, you deserve to be hacked.
-- former White House cybersecurity adviser Richard Clarke