RE: Download Accelerator Plus can be tricked to download malicious file

I didn't see this as a DAP fail, is normal to have out because of network
configuration, but, how you can make your own Server to be detected as a
mirror of the file. I mean if you could do this is that a fact nut by know
for me is not a flaw.

What do you think?

-----Mensaje original-----
De: visitbipin@xxxxxxxxxxx [mailto:visitbipin@xxxxxxxxxxx]
Enviado el: miércoles, 04 de enero de 2006 11:31
Para: bugtraq@xxxxxxxxxxxxxxxxx
Asunto: Download Accelerator Plus can be tricked to download malicious file

Product(ONLY TESTED ON): Download Accelerator Plus (unregistered)
Test Environment: Winxp Pro sp2 (patch level latest)
Risk Type: Rare exception
Threat Level: High

POC screenshots: claims to have 110 million users of DAP world wide and is one
of the popular and best download manager for windows. One of its biggest
strength to download big files in a faster connection at optimum speed is,
it can automatically search for best mirrors and download different parts of
the file form multiple location.

BUT Download Accelerator Plus(DAP) may switch its download to a un trusted
or malicious website while searching for fastest mirrors for a particular
file under certain conditions. If the ACTUAL, trusted host providing the
file is DOWN or due to network congestions the users may get and execute a
malicious file instead.

I've included two screenshots which should be self explanatory. Check out
the url?s in each screenshot and see from where the file is being received
at the end.

In the screenshot I'm trying to download 'Windows 2003 sp1' from but DAP automatically chooses to download it only
from as my network was having tooooooooo low internet
bandwidth at that time.

Further more, on some network/OS there might be rules for MAX CONNECTION PER
HOST and (say)if in the network someone is already downloading some file
from the outcome will surely be a VIRTUAL network
congensation for within that DMZ.

For my test I used another client computer behind the gateway to send
continuous ping ( 17 different instants) to As a
result, for my network was off the radar. So, in my
another computer DAP chooses to download Win2003 sp1 from
instead. So, even after my network gained its full throttle... no-wounder
DAP was still downloading the file from

My test network setup was a 3 computer PC which was left on default
configuration with Winxp sp2 (patchlevel: latest)

Changes: This advisory is slightly modified than the one that I emailed to
the vendor about a week back and tried contacting it, but with no response
till now!

Result: I was receiving the file from an unknown and un-trusted source which
could be infected with a malicious program.

BUT fyi: I haven't researched on HOW and WHERE 'DAP' queries to get other
possible mirrors for the particular file.

Conclusion: I insist NOT to use download managers that does the same while
downloading important files. Or either force your download manager and check
whether the file is being downloaded from the original URL or not.

-Bipin Gautam