Houston, We Have a Problem

Analyzing the Security of Low Earth Orbit Satellites

Johannes Willbold

@jwillbold

/jwillbold

Houston, We Have a Problem

Analyzing the Security of Low Earth Orbit Satellites

Johannes Willbold

@jwillbold

/jwillbold

`$whoami`

Satellite & Space Systems Security
Doctoral Student
- Ruhr University Bochum, DE
Visiting Researcher
- Cyber-Defence Campus, CH
Co-Founder of the SpaceSec Workshop

Space Odyssey

44th IEEE Symposium on Security and Privacy (S&P)

Distinguished Paper Award

Applications

Telecommunications

Research

Technology Testing

Global Positioning

Earth Obervation

Satellite Orbits

MEO

2k - 35k km

LEO

160 - 2k km

GEO

35786 km

Context

Space Segment

34 cm

10 cm

3U CubeSat

ISL

Context

Ground Segment

Space Segment

ISL

Context

Ground Segment

Space Segment

ISL

Space Protocol

Context

User Segment

Ground Segment

Space Segment

ISL

Space Protocol

Firmware Attacks

Our Journey ...

Bigger Picture

Survey

System Analysis

Live Demo

Firmware Attacks

ViaSat Incident

Ground Segment

Space Segment

User Segment

Firmware Attacks

Ground Segment

Space Segment

Attackers

Not so Novel

Outdated Assumptions

Myth of Inaccessibility

$$$ → $

Affordable Ground Stations

Ground Station as a Service
GSaaS

More Satellites
GEO → LEO

Security by Obscurity

No Insights <=> No Attacker

Security by Obscurity

~~No Insights <=> No Attacker~~

Commercial off-the-Shelf (COTS)
Components

Higher Stakes
Critical Infrastructure

More Developers

More People Involved

Attacker Goals

Denial of Service

Malicious Data Interaction

Seizure of Control

Attacker Goals

Seizure of Control

Components

Payload

Bus

Components

COM

Payload

CDHS

EPS

ADCS

TC / TM Flow

COM

Payload

CDHS

Telecommand (TC)

Telemetry (TM)

Decode
Authenticate
Repackage

Parse
Execute
Respond

EPS

ADCS

COM

PDHS

CDHS

Decode
Authenticate
Repackage

Parse
Execute
Respond

EPS

ADCS

PLCOM

TC / TM Flow

Payload Traffic

TC / TM Traffic

Attack Path

PDHS

PLCOM

COM

CDHS

Bus

Attack Path

PDHS

PLCOM

Hack CySat 2022 & 2023
CySat 202

COM

CDHS

Bus

Attack Path

Bypass COM Protection
- Missing AC
- Insecure Protocol
- Outdated Crypto
- Timing Side Channels
- Leaked Keys
- Timed Backdoor
- ...

COM

CDHS

Bus

Attack Path

Bypass COM Protection
- [...]

COM

CDHS

Deploy Attacker Payload
- Firmware Update
  - Signed Image
  - Slow Upload
  - Complex System

Bus

Attack Path

Bypass COM Protection
- [...]

COM

CDHS

Bus

Deploy Attacker Payload
- ~~Firmware Update~~
- Dangerous TC
- Vulnerable TC

Hijack Bus Control Flow
Full Bus Privileges

Objectives

Bypass COM Protection

Dangerous / Vulnerable TC

Hijack Bus Control Flow

Full Bus Privileges

Satellite Case Studies

Approach

System Design

Protocols

ESTCube-1

ESTCube-1

Peripherals

E-Sail (E. Solar Wind Sail) Propulsion

Bus Platform

ARM STM32

Developed by University of Tartau

Custom Protocol

Sender Subsystem ID

Recipient Subsystem ID

Flow Control Flags

Inner Payload

Fletcher-16 Checksum

TX seq.

RX seq.

COM

ID	Subsystem
0	EPS
1	COM
2	CDHS
...
5	Ground Station

	bit 0	bit 1	bit 2	bit 3	bit 4	bit 5	bit 6	bit 7
Byte 0
Byte 1
Byte 2
Byte 3
...

Command Identifier (MSB)

Command Identifier (LSB)

Source

Block ID

Length

Args

Security Analysis

Bypass COM Protection
- Missing TC Protection

COM

CDHS

int sch_handle_command(scheduler_packed_cmd_t ∗pCmd) {
 // ! simplified !
 sch_unpack_command(&g_command, pCmd);
 // ...
 handler_func = &handler_table[g_command.handler_func_index] ;
 // ...
 retval = (∗handler_func) (&g_command) ;
}

	bit 0	bit 1	bit 2	bit 3	bit 4	bit 5	bit 6	bit 7
Byte 0
Byte 1
Byte 2
Byte 3
...

Command Identifier (MSB)

Command Identifier (LSB)

Source

Block ID

Length

Args

Security Analysis

Bypass COM Protection
- Missing TC Protection

COM

CDHS

int sch_handler_set_raw_memory(scheduler_cmd_t* pCmd) {
  raw_mem_access_cmd_t* pAddr = pCmd−>pCmdArgs;
  char* pWriteData;

  if (pAddr) {
    if (g_sch_exec_mode != 1 ) { 
      /* exception and return */ 
    }
    char* pWriteData = &pAddr−>start_of_data_buf;
    if (pAddr−>filesystem_target) {
      // [...]
    } else {
      memcpy(pAddr−>targetAddr, 
             &pAddr−>start_of_data_buf, 
             pAddr−>writeLength);
    }
  }
  // ...
}

Real-World Test

Bypass COM Protection
- Missing TC Protection

COM

CDHS

Deploy Attacker Payload
- Dangerous TC

Image Source: Maximilian Gerhardt, Reverse Engineering Satellite Firmware for Security Evaluation, 13. Dec. 2021

Real-World Test

Bypass COM Protection
- Missing TC Protection

COM

CDHS

Deploy Attacker Payload
- Dangerous TC

Bus

Hijack Bus Control Flow
- ?
Full Bus Privileges
- ?

OPS-Sat

System Chart

Experimenter

Operated by ESA

Open for Research

Peripherals

S-/X-Band, SDR, Optical Rx., Camera, ...

System Chart

CCSDS Protocol Stack

ARM Cortex A9, Yocto Linux

AVR32 AT32UTC3, FreeRTOS

Cubesat Space Protocol (CSP)

System Chart

AVR32 AT32UTC3, FreeRTOS

Cubesat Space Protocol (CSP)

UHF-Stack

/ libcsp

Cubesat Space Protocol (CSP) v1

Source: https://en.wikipedia.org/wiki/Cubesat_Space_Protocol

TCP/IP Oriented Design

Cubesat Space Protocol (CSP) v1

UHF-Stack

Cubesat Space Protocol (CSP) v1

HMAC-SHA1 Authentication
XTEA Encryption Support

Security Issues

MAC comparison leaks timing data #44
- memcmp to compare the digest
HMAC doesn't protect headers #45
- Same problem for the CRC checks
XTEA encrypt packet nonce too predictable #162
- const uint32_t nonce = (uint32_t)rand();

Authors: Issues fixed in libcsp v2

Security Features

UHF-Stack

Cubesat Space Protocol (CSP) v1

HMAC-SHA1 Authentication
XTEA Encryption Support

Security Issues

MAC comparison leaks timing data #44
- memcmp to compare the digest
HMAC doesn't protect headers #45
- Same problem for the CRC checks
XTEA encrypt packet nonce too predictable #162
- const uint32_t nonce = (uint32_t)rand();

Authors: Issues fixed in libcsp v2

Security Features

System Chart

CCSDS Protocol Stack

AVR32 AT32UTC3, FreeRTOS

CCSDS - Protocol Stack

S-Band Stack

Space Packet Protocol

Sync. and Channel Coding Sublayer

Message Abstraction

...

IPSec

TM Space Link Protocol

TC Space Link Protocol

AOS Space Data Link P.

Proximity-1

Data Link Lay.

CCSDS - Protocol Stack

S-Band Stack

Space Packet Protocol

Sync. and Channel Coding Sublayer

Message Abstraction

...

IPSec

TM Space Link Protocol

TC Space Link Protocol

AOS Space Data Link P.

Proximity-1

Data Link Lay.

Unprotected TCs

int csp_route_security_chek(...) {
  if (packet->id.flags & CSP_FXTEA) {
    csp_log_error("Received XTEA encrypted packet, but CSP was compiled without XTEA support. Discarding packet");
  }
  
  // ...
  
  if (packet->id.flags & CSP_FHMAC) {
    csp_log_error("Received packet with HMAC, but CSP was compiled without HMAC support. Discarding packet");
  }
  
   // ...
}

COM

Unprotected TCs

Bypass COM Protection
- Missing TC Protection

COM

CDHS

int sch_handler_set_raw_memory(scheduler_cmd_t* pCmd) {
  raw_mem_access_cmd_t* pAddr = pCmd−>pCmdArgs;
  char* pWriteData;

  if (pAddr) {
    if (g_sch_exec_mode != 1 ) { 
      /* exception and return */ 
    }
    char* pWriteData = &pAddr−>start_of_data_buf;
    if (pAddr−>filesystem_target) {
      // [...]
    } else {
      memcpy(pAddr−>targetAddr, 
             &pAddr−>start_of_data_buf, 
             pAddr−>writeLength);
    }
  }
  // ...
}

Vulnerable TC

Message Abstraction Layer (MAL)

S-Band

Space Packet Protocol (SPP)

PUBSUB_MonitorEvent

SUBMIT_SetPowerState

INVOKE_GetGPSData

...

PROGRESS_GetSummary

Custom Byte Parsing

ADCS Server

...

UHF

Cubesat Space Protocol (CSP)

Parameter DB

CSP => SPP

Space Packet Protocol

Message Abstraction

void task_adcs_servr() {
  char log_file_name [32];

  csp_listen(socket, 10);
  csp_bind(socket, port);
  
  do {
    do {
      conn = csp_accept(socket, 0xff);
    } while (do_wait_for_conn);
    
    packet = csp_read(conn, 10);
    if (packet) {
      packet_data = packet->data;
      switch(*packet_data) {
        // [...]
        case SET_LOGFILE: {
          packet_data = packet->data + 0xf;
          log_file_name[0] = '\0';
          strcat(log_file_name,packet_data);
          // ...
        }
      }
    }
  }
}

Vulnerable TC

ADCS Server

Cubesat Space Protocol (CSP)

Defenses - 404?

Bypass COM Protection
- Missing TC Protection

COM

CDHS

Deploy Attacker Payload
- Vulnerable TC

Bus

Hijack Bus Control Flow
Full Bus Privileges

No OS-Defenses
- ASLR
- NX Stack
No SW-Defenses
- Stack Cookies

Privilege-free RTOS

Demo Setup

Emulation Overview

QEMU

AVR32

OBSW

Simulation Agent

Sensors

UHF

TC Handlers

Telecommand

Telemtry

TCP

Flight Manuvers

Sensor Values

AVR32-QEMU

404 - AVR32 Not Found

Florian Göhler
AVR32 in QEMU from Scratch
Incl. I2C, SPI, PDCA, etc.
Blog:
- How to add a new architecture to QEMU - Part 1-4

QEMU

AVR32

Exploitation

Exploit

Hijack Control Flow

Patch Live Firmware

Add "Password" to TC stack

...

$$$

Exploit

Hijack Control Flow

void init_adcs(void) {
  gpio_enable_module((gpio_map_t *)GPS_USART_GPIO_MAP.18362,2);
  usart_init(1,32000000,0x2580);
  // ...
  cmd_adcs_setup();
  adcs_node_set(1,0x14);
  xTaskGenericCreate(task_adcs,"ADCS",0x2000, 0x0, 8, &pvStack_18, 0x0, 0x0);
  xTaskGenericCreate(task_adcs_server, "ASRV", 0x1000, &adcs_server_port, 9, &pvStack_18, 0x0, 0x0);
  return;
}

void task_adcs_servr() {
  // ...
  
  do {
    // ...
    packet = csp_read(conn, 10);
    if (packet) {
      packet_data = packet->data;
      switch(*packet_data) {
        // [...]
        case SET_LOGFILE: {
          packet_data = packet->data + 0xf;
          log_file_name[0] = '\0';
          strcat(log_file_name,packet_data);
          // ...
        }
      }
    }
  }
}

Exploit

Hijack Control Flow

void GS_ADCS_Log_Start(char *filename, void *pkt_data, uint param_3) {
  char sprintf_buf [60];
  // ...
  __n = sprintf(sprintf_buf,"%s\n%7.6f\n%3.1f\n%u%u%u%u%u\n", filename, ...);
  // ...
  fd = fopen(filename, "wb");
  // ...
  fwrite(&data, 1, __n, fd);
}

case SET_LOGFILE: {
  packet_data = packet->data + 0xf;
  log_file_name[0] = '\0';
  strcat(log_file_name,packet_data);
  
  adcs_logdata._20_4_ = csp_hton32( packet->data[...] | ... );
  adcs_logdata._24_4_ = csp_hton32( packet->data[...] | ... );
  adcs_logdata[28] = packet->data[10];
  adcs_logdata[29] = packet->data[0xb];
  // ...
  adcs_get_jdate();
  
  GS_ADCS_Log_Start(log_file_name, packet_data, pcVar7)
}

Exploit

Hijack Control Flow

I2C

CSP

TM Sender

ADCS Server

CSP -> SPP

Parameter DB

CSP Handlers

Device Cmds.

TC Buffer