Threat Level: green Handler on Duty: Russ McRee

SANS ISC: Retrieving malware over Tor - SANS Internet Storm Center SANS ISC InfoSec Forums


Sign Up for Free!   Forgot Password?
Log In or Sign Up for Free!
Retrieving malware over Tor

A couple of years ago, Lenny Zeltser wrote a diary entry on how to use curl to retrieve malware samples.

If you don't want to disclose your public IP address when retrieving malware, you can use proxies. One way to do this, is to use the Tor anonimity network.

On Linux and OSX, it's quite easy to do so.

You install the tor and torsocks packages for your distro, start tor, and then launch your curl or wget command via torsocks.

torsocks curl http://www.example.com/page -D headers.txt -o sample.vir

Mind you, the Tor network can be slow or unstable sometimes, which may interfere with the sample download. And Tor nodes might also be blocked in countries where you want to download samples from.

On Windows, you can use Tor but not torsocks.

For curl, that's not a problem. You just instruct curl to use the Tor socks proxy with option --socks5-hostname:

curl --socks5-hostname localhost:9050 http://www.example.com/page -D headers.txt -o sample.vir

For wget, it's a bit more complex, because wget can't talk to Socks directly. wget can talk to a HTTP/HTTPS proxy, so you can setup such a proxy between Tor and wget.

 

Didier Stevens
Microsoft MVP Consumer Security
blog.DidierStevens.com DidierStevensLabs.com

DidierStevens

281 Posts
ISC Handler
torrc:
VirtualAddrNetworkIPv4 10.192.0.0/10
AutoMapHostsOnResolve 1
SocksPort 127.0.0.1:9050
TransPort 127.0.0.1:9040
DNSPort 127.0.0.1:9053
ControlPort 9051
DisableDebuggerAttachment 0
ExitNodes {US}
StrictNodes 1


set ExitNodes country codes for geolocked sites (http://www.b3rn3d.com/blog/2014/03/05/tor-country-codes/)

all scripts use '$1" as site ie "wgettor www.google.com". I usually use a single quote like: wgettor 'https://badsite[.]com'

wgettor (grab single file)
torsocks wget --max-redirect 100 --no-check-certificate -S -U 'Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko' "$1"

wgettordir (grab entire directory)
torsocks wget --recursive --no-parent --no-check-certificate -R index.html* -S -U 'Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko' "$1"

wgettornoua (useful for malware that detects UA or use a keep-alive only type of request)
torsocks wget --max-redirect 100 --no-check-certificate -S -U "" "$1"

wgettorref (useful for malware that looks for a referer, use as wgetttorref "referer" "site")
torsocks wget -S --referer="$1" -U 'Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko' --header="Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5" --header="Accept-Language: en-us,en;q=0.5" --header="Accept-Encoding: gzip,deflate" --header="Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7" --header="Keep-Alive: 300" "$2"
James

32 Posts
Thanks!
DidierStevens

281 Posts
ISC Handler

Sign Up for Free or Log In to start participating in the conversation!