attack-tree.md

Attack Tree Analysis for nextcloud/server

Objective: Gain Unauthorized Access to User Data and/or Administrative Control [CRITICAL]

Attack Tree Visualization

Gain Unauthorized Access to User Data and/or Administrative Control [CRITICAL]
/                                   |                                   \
-----------------------------------------------------------------------------------------------------------------
|                                                                       |                                                                       |
Exploit Vulnerabilities in Core Server Code      Compromise 3rd-Party Apps/Integrations                                 Abuse Server Configuration/Features                                  Physical Access to Server
/                                               |                                                                       /           |
|                                               |                                                                       |           |
RCE [CRITICAL]                                  RCE [CRITICAL]                                                               Misconfigured  Weak/Default
                                                                                                                            Sharing       Credentials
        |                                      |                                                                      |           |
        |                                      |                                                                      |           |
        V                                      V                                                                      V           V
   (Examples)                               (Examples)                                                              (Examples)
   - Unpatched known                        - App-specific RCE [CRITICAL]                                             - Publicly    - Default
     vulnerability  -> HIGH RISK ->                                                                                    accessible    admin/user
                                                                                                                     shares        password
                                                                                                                     -> HIGH RISK-> - Overly      -> HIGH RISK->
                                                                                                                                   permissive   - Easily
                                                                                                                                   sharing       guessable
                                                                                                                                   settings      passwords
                                                                                                                                                [CRITICAL]
                                                                                                                     ->HIGH RISK-> - No 2FA
                                                                                                                                   enabled
                                                                                                                                                |
                                                                                                                                                |
                                                                                                                                                V
                                                                                                                                           Direct Access to Server
                                                                                                                                           Hardware [CRITICAL]

Attack Tree Path: 1. Exploit Vulnerabilities in Core Server Code

• RCE (Remote Code Execution) [CRITICAL]
  • -> HIGH RISK -> Unpatched known vulnerability:
    • Description: Exploiting a publicly known and documented vulnerability in the Nextcloud server code for which a patch is available but has not been applied.
    • Likelihood: High (if patching is not diligent).
    • Impact: Very High (complete system compromise).
    • Effort: Medium (exploit code may be publicly available).
    • Skill Level: Intermediate to Advanced.
    • Detection Difficulty: Medium to Hard.

Attack Tree Path: 2. Compromise 3rd-Party Apps/Integrations

• RCE (Remote Code Execution) [CRITICAL]
  • -> HIGH RISK -> App-specific RCE:
    • Description: Exploiting a vulnerability within a third-party Nextcloud app to execute arbitrary code on the server.
    • Likelihood: Medium (depends on app security and popularity).
    • Impact: High to Very High (potential for full system compromise).
    • Effort: Medium.
    • Skill Level: Intermediate to Advanced.
    • Detection Difficulty: Medium to Hard.

Attack Tree Path: 3. Abuse Server Configuration/Features

• Misconfigured Sharing

  • -> HIGH RISK -> Overly permissive sharing settings:
    • Description: Users or administrators configuring file shares with overly broad permissions (e.g., public shares with write access), allowing unauthorized access or modification of data.
    • Likelihood: High (due to user error or lack of awareness).
    • Impact: Low to High (depends on the sensitivity of the shared data).
    • Effort: Very Low.
    • Skill Level: Novice.
    • Detection Difficulty: Easy to Medium.

• Weak/Default Credentials

  • -> HIGH RISK -> Easily guessable passwords:
    • Description: Using weak, easily guessable, or default passwords for user or administrator accounts.
    • Likelihood: Medium to High (common security lapse).
    • Impact: Very High (complete account compromise, potential for full system compromise).
    • Effort: Very Low.
    • Skill Level: Novice.
    • Detection Difficulty: Easy (through failed login attempt monitoring).
  • Default admin/user password [CRITICAL]
    • Description: Using default administrative or user passwords that come with the software.
    • Likelihood: Medium to High.
    • Impact: Very High.
    • Effort: Very Low.
    • Skill Level: Novice.
    • Detection Difficulty: Easy.
  • -> HIGH RISK-> No 2FA enabled:
    • Description: Not enabling Two-Factor Authentication, which significantly increases the risk of account compromise if credentials are stolen or guessed.
    • Likelihood: Medium (depends on administrative policy).
    • Impact: High (amplifies the impact of credential compromise).
    • Effort: N/A (vulnerability, not an attack step).
    • Skill Level: N/A.
    • Detection Difficulty: N/A.

Attack Tree Path: 4. Physical Access to Server

• Direct Access to Server Hardware [CRITICAL]:
  • Description: Gaining physical access to the server hardware, allowing bypassing of software-level security controls.
  • Likelihood: Very Low to Low (depends on physical security).
  • Impact: Very High (complete system compromise).
  • Effort: Medium to High.
  • Skill Level: Intermediate to Advanced.
  • Detection Difficulty: Very Hard.