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Created October 7, 2015 22:01
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Useful commands
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useful_commands.md

Useful Commands

Some of it related to embedded analysis, some of it not.

Table of Contents

Dump or copy via nc

On destination: nc -l 4444 > incoming.tar.bz2 On source: tar -jcv files dirs files | nc <client> 4444

Alternatives

On destination: nc -l 4444 | tar -jxvk
On source: tar -jcv /[^p]* | nc <client> 4444 (avoid proc)
or source: tar -zxcv / --one-file-system / | nc <client> 4444 (full gnu tar, restrict to disk)
or source: dd if=/dev/mtdblock0 bs=2048 | nc <client> 4444 (block device)

If destination cannot listen you can also reverse the order with:

On destination: nc <source_ip> 4444 > incoming
On source: cat outgoing | nc -l 4444

Check rules on destination firewall (iptables/ufw linux/ubuntu, 'ipfw add allow 4444 from any to any' osx) and source (iptables -A OUTPUT -j ACCEPT)

Dump or copy via ssh

From destination: ssh root@source "tar -czpf - /" > sshfs.tar.gz
From source: tar -cpf - / | ssh user@destination "tar xpf - -C dest_dir"
Or from source: cd /; tar -czpf - $(ls /|grep -v proc|grep -v sys) | ssh -o PubkeyAuthentication=no -o PreferredAuthentications=password user@dest "cat > fs.tar.gz"

If you need to open your firewall (iptables -A OUTPUT -j ACCEPT same on INPUT if you really do not care about your target). Check with a packet sniffer.

For source to destination method, add temporary user:

dir=$(mktemp --dry-run)
date=$(date -d tomorrow +%Y-%m-%d)
echo "user added will expire in on \"$date\" with home at \"$dir\""
sudo userdel tmpuser
sudo useradd --expiredate $date --no-user-group \
	-c "Tmp user" --create-home --home "$dir" \
	--shell /bin/bash tmpuser
sudo passwd tmpuser

Copy proc or sys

SRC=/proc
DST=/var/tmp
mkdir -p $DST/$SRC
find $SRC | while read F ; do
   echo $F | grep "proc/kmsg"     && continue #blocking
   echo $F
   test -L $F && cp -a $F $DST/$F && continue #symlink
   test -d $F && mkdir $DST/$F    && continue #directory
   test -f $F && cat $F > $DST/$F && continue #file
done

TFTP walk

Given a file list

for file in file1 file2 file3
do
	echo get $file | tftp <TARGET_IP>
done

tcpdump filters

tcpdump -i <inteface> not port 22
tcpdump -n -w output.cap -i <inteface> not port 22 (-n ignore hostname, add -s 0 to save full packet)

Check SSL Certificates

Using cut+paste of cert: openssl x509 -text -noout
Using file: openssl x509 -text -noout -in /tmp/file
Checking priv key: openssl rsa -text -noout -in /tmp/privkey.pem
For public keys add: -pubin

Comparing to values of the modulos to see that they correspond to eachother.

-noout: write result to stdout
-text: output information about in plaintext form.

Get rsa pubkey from priv: openssl rsa -text -pubout -in /tmp/privkey

OSX DHCPD/TFTPD

# Add host:
sudo gvim /etc/bootptab
sudo /bin/launchctl load -w /System/Library/LaunchDaemons/bootps.plist
sudo /bin/launchctl unload -w /System/Library/LaunchDaemons/bootps.plist
sudo /bin/launchctl load -w /System/Library/LaunchDaemons/tftp.plist
sudo /bin/launchctl unload -w /System/Library/LaunchDaemons/tftp.plist

Optionbally bootpd will start when enabling internet sharing.

Linux DHCP Server

alias s=sudo
s killall dhclient
s ifconfig eth0 192.168.1.1 netmask 255.255.255.0
d=`mktemp -d`
cat >$d/dnsmasq.conf << EOF
 dhcp-option=option:router,192.168.1.1
 dhcp-range=192.168.1.10,192.168.1.254,255.255.255.0,96h
EOF
dnsmasq -d -i eth0 \
 --conf-file=$d/dnsmasq.conf \
 --leases-file=$d/leases \
 --pid-file=$d/pid

s sysctl .net.ipv4.ip_forward
s sysctl .net.ipv4.ip_forward=1
# NAT
s iptables -A FORWARD -i wlan0 -o eth0 -s 192.168.1.0/24 -m conntrack --ctstate NEW -j ACCEPT
s iptables -A FORWARD -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
s iptables -A POSTROUTING -t nat -j MASQUERADE
# OR
#s iptables -A POSTROUTING -t nat -o eth0 -j MASQUERADE

OSX DNS

The DNS proxy used with internet sharing for pre Mavericks used named zones. For > Mavericks mDNSResponder is used (source code). It might be possible to configure the zones somehow but I could not figure it out yet (dig around /etc/dnsextd.conf). Instead I'm using dnsmasq (discussions 1 2). In fact you should use dnsmasq anyway. Apple appear to change their DNS/Bootp/InternetSharing configurations every release:

#execute this interface before executing dhcpd or internet sharing
sudo ifconfig en0 192.168.2.1
sudo dnsmasq --no-daemon -listen-address=192.168.2.1 \
     --address=/localtest./192.168.2.22

Test passthrough dig @192.168.2.1 google.com and localtest dig @192.168.2.1 localtest.

To configure InternetSharing or bootpd to provide clients with your IP edit /etc/bootpd.plist and /etc/bootptab if you want to provide a file.

<key>dhcp_domain_name_server</key>
<array>
        <string>192.168.2.1</string>
</array>

Remote Wireshark

Only works on wireshark installations that support the option to pipe input. Tcpdump output of <remote_listener> eth0 over SSH to local wireshark:

ssh <remote_listener> tcpdump -s0 -w - 'not port 22' | wireshark -k -i -

Embedded Tcpdump

If a target device does not provide TCP dump, or any other bin for that matter, you can attempt to find one mostly compatible with the target linux system using a distro's cross platform packages, such as debian.

Download:

Just download copy some tcpdump for the platform. When you execute you should get some errors telling you the version of libc you need, or libpcap. Then walk back through different distro releases until you find a tcpdump with prerequisites that seem to match those required on the platform.

Extract packages, such as: ar -x libpcap0.8_0.9.5-1_mipsel.deb && tar zxvf data.tar.gz. Then Copy over somehow.

On target:

  • ln -s libpcap.so.0.8 libpcap.so.0.9.8

Unix Socket debug

Can use either Netcat-openbsd, socat or strace. These methods, except for strace, allow you to debug and connect (see):

  • nc -U /path/to/unixsocket
  • socat UNIX-CONNECT:/path/to/unixsocket STDIN
  • strace -e trace=read,write -e read=29,30 -e write=29,30 -p <pid> 29,30 are file descriptors (lsof or proc)

For embedded target example - netcat-openbsd:

wget http://ftp.de.debian.org/debian-archive/debian/pool/main/n/netcat-openbsd/netcat-openbsd_1.89-3_mipsel.deb
wget http://ftp.de.debian.org/debian-archive/debian/pool/main/g/glib2.0/libglib2.0-0_2.16.6-3_mipsel.deb
wget http://ftp.de.debian.org/debian-archive/debian/pool/main/p/pcre3/libpcre3_7.6-2.1_mipsel.deb
wget http://ftp.de.debian.org/debian-archive/debian/pool/main/v/vim/vim-common_7.0-122+1etch5_mipsel.deb
for deb in ./*.deb; do ar -x $deb; tar zxvf data.tar.gz; done
tar -cf nc.tar bin/nc.openbsd usr/lib/libglib-2.0.so.0* usr/lib/libpcre.so.3* usr/bin/xxd
cat nc.tar | nc -l 4444

target:

nc 192.168.2.1 4444 > /var/tmp/nc.tar
cd /var/tmp
tar xvf nc.tar
LD_LIBRARY_PATH=/var/tmp/usr/lib /var/tmp/bin/nc.openbsd -U /path/to/unixsocket | /var/tmp/usr/bin/xxd

Or socat:

wget http://ftp.de.debian.org/debian-archive/debian/pool/main/s/socat/socat_1.4.3.1-1_mipsel.deb
wget http://ftp.de.debian.org/debian-archive/debian/pool/main/r/readline5/libreadline5_5.2-2_mipsel.deb
wget http://ftp.de.debian.org/debian-archive/debian/pool/main/n/ncurses/libncurses5_5.5-5_mipsel.deb
for deb in ./*.deb; do ar -x $deb; tar zxvf data.tar.gz; done
tar -cf socat.tar usr/bin/socat lib/libreadline* lib/libncurses* 
cat socat.tar | nc -l 4444

target (plugin.ctl socket in question):

nc 192.168.2.1 4444 > /var/tmp/socat.tar
cd /var/tmp
tar xvf socat.tar
SOCKET=/var/run/plugin.ctl
mv $SOCKET /var/run/sock.original && \
LD_LIBRARY_PATH=/var/tmp/lib /var/tmp/usr/bin/socat -t100 -x -v UNIX-LISTEN:$SOCKET,mode=777,reuseaddr,fork UNIX-CONNECT:/var/run/sock.original && \
mv /var/run/sock.original $SOCKET

Gigbit Sniffing

The world of devices are moving to gigabit only interfaces. A simple hub for sniffing might not due. Using a 2nd gigabit network card setup a bridge (linux/osx) with:

sudo ifconfig bridge0 create
sudo ifconfig bridge0 addm en0 addm en6
sudo ifconfig bridge0 up

MiTM SSL

Via burp, Via apache, Via mitmproxy from cortesi, Via proxystrike. In firefox might set in about:config to true: browser.xul.error_pages.enabled and browser.xul.error_pages.expert_bad_cert.

  • Burpsuite:
    • Import a given cert from target
    • Export burp's self signed cert
      • import to browser
      • import to java: keytool -import -alias burl -file <exportedburpcertfile>
    • PS: if require upstream proxy fill in under burp Options / Connections / Upstream Proxy Servers. eg.: Dest *, host , port . Likely do NOT require transparent proxying then in the Proxy / Options

Quick split of file into parts

for i in 0x06171cb4 0x06671547; do splitfile.sh <filename> $i 0xffffffff <filename>_$i; done

or

for i in 0x06171cb4 0x06671547; do dd bs=1 if=<filename> skip=$i of=<filename>_$i; done

Connecting to onioned ssh

Using Tor to remotely connect to a SSH host behind iron-curtains.

On server:

mkdir /var/lib/tor/ssh and set in torrc HiddenServiceDir /var/lib/tor/ssh/ and HiddenServicePort 22 127.0.0.1:22. To find onionhostname cat /var/lib/tor/ssh.

On client:

Add to ~/.ssh/config Host *.onion and ProxyCommand socat STDIO SOCKS4A:localhost:%h:%p,socksport=9050. Optionally add a helpfull alias that uses netcat to route through tor alias tor-ssh='ssh -o ProxyCommand="nc -X 4 -x localhost:9050 %h %p"'. now ssh [email protected]

Binary Edit on Shell

  • Example with base64 encoded binary:
    echo "cSEk" | base64 -d | xxd -p | sed 's/71/72/' | xxd -p -r | base64
    turns "q!$" into "r!$"
    "cSEk" is base64 for "q!$"
    xxd turns the binary hex string
    sed changes the hex (0x71=q, 0x72=r)
    xxd turns modified hex into binary

Dynamic Assisted RE

Find PID's with known thread or process name (also try sched in addition to comm):

find /proc -name comm | while read F; do 
  grep gps $F >/dev/null && echo $F; 
done

Find pid's that load a library, show offset:

find /proc -name maps | while read F; do 
  grep -i driver.so $F && echo $F; 
done

Find pid responsible for network port:

# Monitor on target with:
for pid in `ls`; do
  echo -en "\n\n$pid\n";
  strace -i -v -p $pid 2>&1 \
   | egrep -v 'read|mmap|fstat|open|time|ioctl|write|lseek|pselect|munmap|close|sigreturn|tgkill|nanosleep|rt_sig|restart_|select|pause|futex|SIGUSR1|gettid|madvise|exit|get_robus|clone|child_stack|detached|unfinished' &
  sleep 5 && killall strace;
done

# Stimulate from other host with:
while [ 1 ]; do 
  echo "qwerty" | nc $IP $PORT & p=$!; 
  sleep 1 && kill $p; 
done

MITM Layer 2

Ettercap: s ettercap -T -Q -i wlan0 -o -M arp /<ROUTER>/ /<TARGET>/ (T text interface, Q superquiet, o onlymitm)

Examples (from man)

ettercap -T -M arp // //
   Perform the ARP poisoning attack against all the hosts in the LAN.
ettercap -T -M arp:remote /192.168.1.1/ /192.168.1.2-10/
   Perform  the  ARP poisoning against the gateway and the host in the
   lan between 2 and 10. The 'remote' option is needed to be able to 
   sniff the remote traffic the hosts make through the gateway.
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