Cosmic Conquest

     Analyzing the Security of Low Earth Orbit Satellites

Johannes Willbold

$whoami

  • Satellite & Space Systems Security
  • Doctoral Student
    • Ruhr University Bochum, DE
  • Visiting Researcher
    • Cyber-Defence Campus, CH
  • General Chair @ SpaceSec Workshop

Space Odyssey

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

Distinguished Paper Award

Firmware Attacks

Our Journey ...

Bigger Picture

Survey

System Analysis

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Outdated Assumptions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

Attack Path

PDHS

PLCOM

COM

CDHS

Bus

Attack Path

PDHS

PLCOM

  • CySat 2023 In Orbit Demonstration
  • CySat 2022

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    • Outdated Crypto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

1

2

3

4

Bypass COM Protection

Dangerous / Vulnerable TC

Hijack Bus Control Flow

Full Bus Privileges

Satellite Case Studies

Approach

System Design

Protocols

ESTCube-1

ESTCube-1

ESTCube-1

Peripherals

E-Sail (E. Solar Wind Sail) Propulsion

Bus Platform

ARM STM32

Developed by University of Tartu

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

2

4

3

CCSDS Protocol Stack

4

ARM Cortex A9, Yocto Linux

2

AVR32 AT32UTC3, FreeRTOS

1

3

1

Cubesat Space Protocol (CSP)

System Chart

2

2

AVR32 AT32UTC3, FreeRTOS

1

1

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

1

 UHF-Stack

Cubesat Space Protocol (CSP) v1

  • HMAC-SHA1 Authentication
  • XTEA Encryption Support

Security Issues

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

Authors: Issues fixed in libcsp v2

Security Features

1

 UHF-Stack

Cubesat Space Protocol (CSP) v1

  • HMAC-SHA1 Authentication
  • XTEA Encryption Support

Security Issues

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

Authors: Issues fixed in libcsp v2

Security Features

1

System Chart

3

CCSDS Protocol Stack

3

2

AVR32 AT32UTC3, FreeRTOS

2

CCSDS - Protocol Stack

S-Band Stack

Space Packet Protocol

IP

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.

3

CCSDS - Protocol Stack

S-Band Stack

Space Packet Protocol

IP

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.

3

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

Test Setup

Emulation Overview

 

QEMU

 

 

AVR32

 

 

OBSW

 

 

Simulation Agent

 

 

Sensors

 

 

UHF

 

 

TC Handlers

 

Telecommand

Telemtry

TCP

TCP

Flight Manuvers

Sensor Values

Flying Laptop

Flying Laptop

Peripherals

De-orbit mechanism, AIS, Camera, etc...

Bus Platform

SPARC LEON 3 - OBC from Airbus S&D

Technology Tester

Co-Developed by
Airbus Space & Defense

CCSDS

Space Packet Protocol

IP

Sync. and Channel Coding Sublayer

Custom

...

IPSec

TM Space Link Protocol

TC Space Link Protocol

AOS Space Data Link P.

Proximity-1

Data Link Lay.

CCSDS - SDLP

Space Link Protocol Header

Frame Data

Space Link Protocol Trailer

CCSDS - SDLS

Space Link Protocol Header

Security Header

Frame Data

Security Trailer

Space Link Protocol Trailer

Bigger Picture

But it's different for [...] satellites.

But it's different for [...] satellites,
.... right?

Developer Survey

 TC Protocols

Custom

Standard

Weight

~ 1.3 kg

~ 5.4 kg

~ 120 kg

Weight ≈ Money

 TC Protocols

Custom / Standard

Weight ≈ Money

1-50 kg 50-100 kg > 100 kg
Standard 1 1 4
Custom 6 1 0
Abstains 3 0 1
∑ 10 2 5

=> Inaccessible Standard

TC Protection

Question: Are any measures deployed to prevent 3rd parties from controlling your satellite?

Unknown*:

Prefer not to say / Don't know

2

4

6

8

9

3

5

Yes

No

Unknown*

 TC Obscurity

Question: What measures are deployed to prevent 3rd parties from controlling your satellite? (Multiple Answers)

2

4

4

5

Access Control

Encryption

3

*: Special knowledge about ....

Special permit needed

* ... Frequences, Modulation, etc.

* ... Protocols

3

2

Road to IOD

Road to IOD

Emulation

Hardware Tests

In Orbit

Static Analysis

 Why no IOD?

Nobody said Yes

Limited Academic Value

 Why IOD?

More convincing than Emulation

Huge Public Impact

Enormous Educational Value

Lesson Learnt

Lessons Learnt

Firmware Attacks on Satellites are a Thing

ViaSat Incident != Satellite Firmware Attack

Common Sat Protocols lack Security

Security by Obscurity

Lessons Learnt

Missing State-of-the-Art Defenses

Missing TC Protection

Long Road to IODs

Reasons for and against IODs

Thanks!

  • Firmware Attacks on Satellite
  • Satellite Exploitation Objectives
  • Three Satellite Case Studies
  • Satellite Developer Survey
  • Road to IODs

/jwillbold

Johannes Willbold - johannes.willbold@rub.de

[1] ESTCube-1 Image: https://www.eoportal.org/satellite-missions/estcube-1

[2] OPS-Sat Image: https://www.esa.int/ESA_Multimedia/Videos/2019/12/OPS-SAT_ESA_s_flying_lab_open_to_all

[3] Flying Laptop Image: https://www.irs.uni-stuttgart.de/en/research/satellitetechnology-and-instruments/smallsatelliteprogram/flying-laptop/