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Issue metadata

Status: WontFix
Owner:
Closed: Mar 2016
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: ----
Pri: ----
Type: Bug



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Download Protection Bypass using Automated File Extension Changing

Reported by picklebo...@gmail.com, Mar 22 2016

Issue description

This template is ONLY for reporting Download Protection Bypass bugs within
Chrome and is not for requesting a review of sites or binaries identified
as malicious.

VERSION
Chrome Version: 49.0.2623.87, stable
Operating System: Windows 10, 1511

REPRODUCTION CASE
Please include a demonstration of the Download Protection / Safe Browsing
bug, such as an attached HTML or binary file that reproduces the bug when
loaded in Chrome. PLEASE make the file as small as possible and remove any
content not required to demonstrate the bug.
**Explanation in HTML file

 
Report.zip
58.2 KB Download
Project Member

Comment 1 by ClusterFuzz, Mar 22 2016

Status: Assigned (was: New)
Another test
Setup.exe
64.2 KB Download
Pasting from .zip
*****************

README.txt:
**In order to test the bug you must run the contents in a server (I used XAMPP, but any stack will do) and not locally opening the file in Chrome, otherwise it will not work!
My code is in the /build folder that I used to make "Program.exe" and the website for the demonstration is in the /htdocs folder. 


From the index.html:
The program "Content.exe" was still passed to the user through the program "Program.exe". This was done by taking the "Content.exe" and converting the ".exe" to a ".txt". Next, I created a batch file that would change the extension automatically when executed and then it would end up launching the malicious code. Then, I put it into a ".exe" using a program called "Advanced BAT to EXE converter v2.94" and packaged the batch program and the malware hidden as a .txt into a single .exe. All the user has to do is simply execute that program and that malicious code is already running and stored on the users' temp folder so it could lead to further damage.

For testing I used a XAMPP stack on my computer and downloaded the two links below. The first one is the example malware taken from "https://testsafebrowsing.appspot.com/" and the second is another file (I will give my binaries that I used to make it) that ends up launching the same code.

Labels: -Restrict-View-Google
Status: WontFix (was: Assigned)
Thanks for the report!

You're effectively wrapping an .exe in another one, which does not bypass safe browsing.  This will still trigger a request to Safe Browsing to analyze your new .exe, so this is WAI and doesn't meet the VRP rules:

https://www.google.com/about/appsecurity/chrome-rewards/
"The download should not send a Download Protection Ping back to Safe Browsing. Download Protection Pings can be measured by checking increments to counters at chrome://histograms/SBClientDownload.CheckDownloadStats. If a counter increments, a check was successfully sent (with exception to counter #7, which counts checks that were not sent)."
Thanks for taking a look at my report!

I'll try to see if I can catch any vulnerabilities and be able to fully bypass
Safe Browsing to were it doesn't send a Download Protection Ping. By the way, what did you mean when you said "so this is WAI"? 
WAI = "Working As Intended"
Labels: Type-Bug

Comment 8 by vakh@chromium.org, Mar 10 2017

Labels: Restrict-View-SecurityTeam
For all Download Protection VRP bugs: removing label Restrict-View-Google and adding Restrict-View-SecurityTeam instead.
Project Member

Comment 9 by sheriffbot@chromium.org, Mar 11 2017

Labels: -Restrict-View-SecurityTeam allpublic
This bug has been closed for more than 14 weeks. Removing security view restrictions.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

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