attack-tree.md

Attack Tree Analysis for signalapp/signal-android

Objective: To compromise the confidentiality, integrity, or availability of user data or communications within an application built using the Signal-Android codebase, by exploiting vulnerabilities or design choices within that codebase.

Attack Tree Visualization

Compromise User Data/Communications (Confidentiality, Integrity, Availability) [CRITICAL]
    /       |       \
   /        |        \
  /         |         \
 /          |          \
/           |           \
---------------------------------------------------------------------------------
|                                             |                                 |
|  1. Exploit Vulnerabilities in             |  4.  Compromise Signal Protocol  |
|     Signal-Android Codebase  [CRITICAL]     |      Implementation             |
|     /       |       \                      |      /           |           \    |
|    /        |        \                     |     /            |            \   |
|   /         |         \                    |    /             |             \  |
| 1.1 Buffer  | 1.2 Logic  | 1.3 Crypto       |  4.2  Side-   | 4.3 Implementation|
| Overflow    |  Errors    |  Flaws           |  Channel     |  Errors in        |
|->(High Risk)|->(High Risk)| (Implementation |  Attacks     |  Ratchet/X3DH     |
|             |           |  Errors) [CRITICAL]|->(High Risk)| ->(High Risk)     |
|             |           | ->(High Risk)     |              |                   |
|---------------------------------------------|----------------------------------
| 2.  Supply Chain Attack                    |
|     (Compromised Dependencies)             |
|     /       |                               |
|    /        |                               |
| 2.1  Direct | 2.2  Transitive                |
|  Dependency|  Dependency                  |
|  Compromise|  Compromise                  |
|->(High Risk)|->(High Risk)                   |
|---------------------------------------------|
| 3.  Compromise of Signal's Infrastructure  |
|     /                                       |
|    /                                        |
| 3.1  Compromised                            |
|  Developer                                  |
|  Accounts                                   |
|->(High Risk)                                |
-------------------------------------------------

Attack Tree Path: 1. Exploit Vulnerabilities in Signal-Android Codebase [CRITICAL]

• 1.1 Buffer Overflow -> (High Risk)

  • Description: Exploiting a buffer overflow vulnerability in the native code (JNI) portions of Signal-Android to achieve arbitrary code execution. This could allow an attacker to completely take over the application.
  • Likelihood: Low
  • Impact: Very High
  • Effort: High
  • Skill Level: Expert
  • Detection Difficulty: Hard

• 1.2 Logic Errors -> (High Risk)

  • Description: Exploiting flaws in the application's logic, such as incorrect state machine handling, race conditions, or improper input validation. This could lead to various security issues, including data breaches or denial of service.
  • Likelihood: Medium
  • Impact: Medium-High
  • Effort: Medium
  • Skill Level: Intermediate-Advanced
  • Detection Difficulty: Medium

• 1.3 Cryptographic Flaws (Implementation Errors) [CRITICAL] -> (High Risk)

  • Description: Exploiting errors in the implementation of cryptographic primitives or protocols. This could lead to the complete compromise of the confidentiality of communications.
  • Likelihood: Low
  • Impact: Very High
  • Effort: Very High
  • Skill Level: Expert
  • Detection Difficulty: Very Hard

Attack Tree Path: 2. Supply Chain Attack (Compromised Dependencies)

• 2.1 Direct Dependency Compromise -> (High Risk)

  • Description: A malicious actor compromises a library directly used by Signal-Android, injecting malicious code that is then incorporated into the application.
  • Likelihood: Low
  • Impact: High
  • Effort: Medium-High
  • Skill Level: Advanced
  • Detection Difficulty: Medium-Hard

• 2.2 Transitive Dependency Compromise -> (High Risk)

  • Description: A dependency of a dependency (or further down the chain) is compromised, leading to the inclusion of malicious code. This is harder to detect and prevent than direct dependency compromises.
  • Likelihood: Medium
  • Impact: High
  • Effort: Medium
  • Skill Level: Intermediate-Advanced
  • Detection Difficulty: Hard

Attack Tree Path: 3. Compromise of Signal's Infrastructure

• 3.1 Compromised Developer Accounts -> (High Risk)
  • Description: An attacker gains access to a Signal developer's account (e.g., through phishing or password theft) and uses this access to push malicious code to the Signal-Android repository.
  • Likelihood: Low
  • Impact: Very High
  • Effort: Medium
  • Skill Level: Intermediate
  • Detection Difficulty: Medium

Attack Tree Path: 4. Compromise Signal Protocol Implementation

• 4.2 Side-Channel Attacks -> (High Risk)

  • Description: Exploiting information leaked through the physical implementation of cryptographic operations (e.g., timing variations, power consumption) to extract secret keys.
  • Likelihood: Medium
  • Impact: High
  • Effort: High
  • Skill Level: Expert
  • Detection Difficulty: Hard

• 4.3 Implementation Errors in Ratchet/X3DH -> (High Risk)

  • Description: Bugs in the implementation of the Double Ratchet or X3DH algorithms, which could compromise forward secrecy or deniability features of the Signal Protocol.
  • Likelihood: Low
  • Impact: Very High
  • Effort: High
  • Skill Level: Expert
  • Detection Difficulty: Hard

• 4.1 Weaknesses in Key Derivation [CRITICAL]

  • Description: Flaws in how cryptographic keys are derived could weaken the security of the entire system.
  • Likelihood: Very Low
  • Impact: Very High
  • Effort: Very High
  • Skill Level: Expert
  • Detection Difficulty: Very Hard