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auclass.c
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auclass.c
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/*-
* xnumon - monitor macOS for malicious activity
* https://www.roe.ch/xnumon
*
* Copyright (c) 2017-2019, Daniel Roethlisberger <daniel@roe.ch>.
* All rights reserved.
*
* Licensed under the Open Software License version 3.0.
*/
#include "auclass.h"
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <bsm/audit.h>
#include <bsm/audit_kevents.h>
/*
* The events that are configured to be part of the custom AC_XNUMON class.
* These lists need to be in line with what is actually handled in evtloop.c.
*/
/*
* Process tracking.
*/
const uint16_t auclass_xnumon_events_procmon[] = {
AUE_FORK, /* fork */
AUE_VFORK, /* vfork */
AUE_POSIX_SPAWN,/* posix_spawn, posix_spawnp +/- POSIX_SPAWN_SETEXEC */
AUE_EXECVE, /* execl, execle, execlp, execv, execve, execvp, execvP */
AUE_MAC_EXECVE, /* __mac_execve */
AUE_EXIT, /* exit */
AUE_WAIT4, /* wait, wait3, wait4, waitpid */
AUE_CHDIR, /* chdir */
AUE_FCHDIR, /* fchdir */
/*
* AUE_FORK1 - syscall not implemented on macOS
* AUE_DARWIN_RFORK - syscall not implemented on macOS
* AUE_EXEC - syscall not implemented on macOS
* AUE_FEXECVE - syscall not implemented on macOS
* Mach task_create - RPC via mach_msg syscall, always fails
*/
0
};
/*
* Tracking of inter-process access for potential manipulation.
*/
const uint16_t auclass_xnumon_events_hackmon[] = {
AUE_PTRACE, /* ptrace */
AUE_TASKFORPID, /* task_for_pid */
/* processor_set_tasks cannot be audited (40755284);
* but seems to be disarmed in 10.14 */
0
};
/*
* File modification tracking.
*
* The number and hotness of the events we need to track here seems excessive;
* there should be better ways to achieve the same.
*/
const uint16_t auclass_xnumon_events_filemon[] = {
AUE_OPEN_W, /* open, open_nocancel, guarded_open_np */
AUE_OPEN_WC,
AUE_OPEN_WT,
AUE_OPEN_WTC,
AUE_OPEN_RW,
AUE_OPEN_RWC,
AUE_OPEN_RWT,
AUE_OPEN_RWTC,
AUE_OPEN_EXTENDED_W, /* open_extended */
AUE_OPEN_EXTENDED_WC,
AUE_OPEN_EXTENDED_WT,
AUE_OPEN_EXTENDED_WTC,
AUE_OPEN_EXTENDED_RW,
AUE_OPEN_EXTENDED_RWC,
AUE_OPEN_EXTENDED_RWT,
AUE_OPEN_EXTENDED_RWTC,
AUE_OPENAT_W, /* openat, openat_nocancel */
AUE_OPENAT_WC,
AUE_OPENAT_WT,
AUE_OPENAT_WTC,
AUE_OPENAT_RW,
AUE_OPENAT_RWC,
AUE_OPENAT_RWT,
AUE_OPENAT_RWTC,
AUE_OPENBYID_W, /* openbyid_np */
AUE_OPENBYID_WT,
AUE_OPENBYID_RW,
AUE_OPENBYID_RWT,
#if 0
AUE_DUP, /* dup */
AUE_DUP2, /* dup2 */
AUE_MMAP, /* mmap */
AUE_MUNMAP, /* munmap */
#endif
AUE_CLOSE, /* close, close_nocancel, guarded_close_np */
AUE_RENAME, /* rename */
AUE_RENAMEAT, /* renameat, renameatx_np */
AUE_LINK, /* link */
AUE_LINKAT, /* linkat */
AUE_SYMLINK, /* symlink */
AUE_SYMLINKAT, /* symlinkat */
AUE_UTIMES, /* utimes */
AUE_FUTIMES, /* futimes */
AUE_COPYFILE, /* copyfile(2) not copyfile(3) */
AUE_CLONEFILEAT, /* clonefileat */
AUE_FCLONEFILEAT, /* fclonefileat */
AUE_UNLINK, /* unlink */
AUE_UNLINKAT, /* unlinkat */
/*
* AUE_CREAT - syscall not implemented on macOS
* AUE_UTIME - syscall not implemented on macOS
* AUE_FUTIMESAT - syscall not implemented on macOS
* AUE_LUTIMES - syscall not implemented on macOS
* AUE_DARWIN_FUTIMES - syscall not implemented on macOS
*/
0
};
/* Socket tracking, TCP only for now. */
const uint16_t auclass_xnumon_events_sockmon[] = {
AUE_SOCKET,
AUE_BIND,
AUE_LISTEN,
AUE_CONNECT,
AUE_ACCEPT,
#if 0
AUE_GETSOCKOPT,
AUE_SETSOCKOPT,
AUE_GETPEERNAME,
AUE_FCNTL,
AUE_RECVMSG,
AUE_SENDMSG,
AUE_RECVFROM,
AUE_SENDTO,
AUE_SHUTDOWN,
#endif
0
};
/*
* Add *classmask* to the classmask of all events in NULL-terminated array of
* event IDs *aues*. This global kernel configuration affects all consumers of
* audit(4), including auditd(8).
*/
int
auclass_addmask(unsigned int classmask, const uint16_t aues[]) {
au_evclass_map_t auem;
for (int i = 0; aues[i]; i++) {
bzero(&auem, sizeof(auem));
auem.ec_number = aues[i];
if (auditon(A_GETCLASS, &auem, sizeof(auem)) == -1) {
fprintf(stderr, "auditon(A_GETCLASS,%u): "
"%s (%i)\n", aues[i],
strerror(errno), errno);
return -1;
}
auem.ec_class |= classmask;
if (auditon(A_SETCLASS, &auem, sizeof(auem)) == -1) {
fprintf(stderr, "auditon(A_SETCLASS,%08x,%u): "
"%s (%i)\n",
auem.ec_class, auem.ec_number,
strerror(errno), errno);
return -1;
}
}
return 0;
}
/*
* Remove *classmask* from the classmask of all events in NULL-terminated array
* of event IDs *aues*. This global kernel configuration affects all consumers
* of audit(4), including auditd(8).
*/
int
auclass_removemask(unsigned int classmask, const uint16_t aues[]) {
au_evclass_map_t auem;
for (int i = 0; aues[i]; i++) {
bzero(&auem, sizeof(auem));
auem.ec_number = aues[i];
if (auditon(A_GETCLASS, &auem, sizeof(auem)) == -1) {
fprintf(stderr, "auditon(A_GETCLASS,%u): "
"%s (%i)\n", aues[i],
strerror(errno), errno);
return -1;
}
auem.ec_class &= ~classmask;
if (auditon(A_SETCLASS, &auem, sizeof(auem)) == -1) {
fprintf(stderr, "auditon(A_SETCLASS,%08x,%u): "
"%s (%i)\n",
auem.ec_class, auem.ec_number,
strerror(errno), errno);
return -1;
}
}
return 0;
}
typedef struct {
const char *name;
unsigned int flag;
} class_t;
class_t classes[] = {
/* non-standard */
{"xm", AC_XNUMON},
{"xnumon", AC_XNUMON},
/* standard */
{"fr", AC_FREAD},
{"fread", AC_FREAD},
{"fw", AC_FWRITE},
{"fwrite", AC_FWRITE},
{"fa", AC_FATTRA},
{"fattra", AC_FATTRA},
{"fm", AC_FATTRM},
{"fattrm", AC_FATTRM},
{"fc", AC_FCREAT},
{"fcreat", AC_FCREAT},
{"fd", AC_FDELET},
{"fdelet", AC_FDELET},
{"cl", AC_FCLOSE},
{"fclose", AC_FCLOSE},
{"pc", AC_PROC},
{"proc", AC_PROC},
{"nt", AC_NET},
{"net", AC_NET},
{"ip", AC_IPC},
{"ipc", AC_IPC},
{"na", AC_NA},
{"ad", AC_ADMIN},
{"admin", AC_ADMIN},
{"lo", AC_LOGIN},
{"login", AC_LOGIN},
{"aa", AC_AUTH},
{"auth", AC_AUTH},
{"ap", AC_APP},
{"app", AC_APP},
{"io", AC_IOCTL},
{"ioctl", AC_IOCTL},
{"ex", AC_EXEC},
{"exec", AC_EXEC},
{"ot", AC_MISC},
{"misc", AC_MISC},
{"all", AC_ALL},
{"file", AC_FILE},
{0, 0}
};
static unsigned int
auclass_parse(const char *s, size_t l) {
for (int i = 0; classes[i].name; i++)
if (!strncmp(s, classes[i].name, l) &&
l == strlen(classes[i].name) &&
classes[i].name[l] == '\0')
return classes[i].flag;
return AC_NONE;
}
unsigned int
auclass_maskparse(const char *s) {
unsigned int classmask = AC_NONE;
const char *begin, *end;
begin = s;
for (;;) {
end = begin;
while ((*end != '\0') && (*end != ','))
end++;
classmask |= auclass_parse(begin, end-begin);
if (!*end)
break;
begin = end + 1;
}
return classmask;
}