attack-tree.md

Attack Tree Analysis for vicc/chameleon

Objective: Compromise the application using vulnerabilities in the vicc/chameleon library, specifically achieving either:

• Execute arbitrary code on the server (RCE).
• Exfiltrate sensitive data processed by the application.

Attack Tree Visualization

                                     +-----------------------------------------------------+
                                     |  Compromise Application via Chameleon Vulnerability  |
                                     +-----------------------------------------------------+
                                                  /                      \
                                                 /                        \
         +-------------------------------------+-----------------+     +-------------------------------------------------+
         |  1. Execute Arbitrary Code (RCE)  |                     |  2. Exfiltrate Sensitive Data / Information Leak  |
         +-------------------------------------+-----------------+     +-------------------------------------------------+
               /                                                              /
              /                                                              /
+-------------+-----+                                           +-------------+-----+
| 1.1 Template  |                                           | 2.1  Template   |
|  Injection   |                                           |   Injection    |
| (XPath/XSLT) |                                           | (Data Exposure)|
| [HIGH RISK]  |                                           | [HIGH RISK]  |
| [CRITICAL]   |                                           | [CRITICAL]   |
+-------------+-----+                                           +-------------+-----+
      |                                                                 |
+-----+-----+                                                     +-----+-----+
|1.1.1 Inject|                                                     |2.1.1  Inject |
| Malicious |                                                     | Malicious  |
| XPath/XSLT|                                                     | Template to|
|  to Eval  |                                                     | Expose     |
| Arbitrary |                                                     | Internal   |
|   Code    |                                                     |  Data      |
| [CRITICAL]   |                                                     | [CRITICAL]   |
+-----+-----+                                                     +-----+-----+
      |
+-----+-----+
|1.1.2 Bypass|
|  Input    |
| Validation|
|  (if any) |
| [CRITICAL]   |
+-----+-----+
       |
+-------+-------+
|1.3.1  Find   |
| Vulnerable |
| Dependency |
|  (e.g.,    |
|  libxml2)  |
| [CRITICAL]   |
+-------+-------+

Attack Tree Path: 1. Execute Arbitrary Code (RCE)

• 1.1 Template Injection (XPath/XSLT) [HIGH RISK] [CRITICAL]
  • Description: This is the primary attack vector for achieving RCE. Attackers exploit vulnerabilities in how the application handles user-supplied input that influences the XSLT template or XPath expressions used by Chameleon. If the application doesn't properly sanitize this input, an attacker can inject malicious XSLT or XPath code.
  • Sub-Steps:
    • 1.1.1 Inject Malicious XPath/XSLT to Eval Arbitrary Code [CRITICAL]:
      • Description: The attacker crafts a malicious XSLT template or XPath expression that leverages features of the XSLT processor to execute arbitrary code on the server. This might involve using functions like xsl:script (if enabled), calling external functions, or exploiting vulnerabilities in the XSLT processor itself.
      • Example: An attacker might inject an XSLT template that uses the document() function to read arbitrary files from the file system, or uses a scripting extension to execute shell commands.
    • 1.1.2 Bypass Input Validation (if any) [CRITICAL]:
      • Description: If the application attempts to validate or sanitize user input, the attacker will try to find ways to bypass these controls. This could involve using character encoding tricks, exploiting flaws in the validation logic, or finding alternative input vectors that are not properly validated.
      • Example: If the application blocks certain characters, the attacker might try using URL encoding or other encoding schemes to represent those characters.
  • 1.3.1 Find Vulnerable Dependency (e.g., libxml2) [CRITICAL]:
    • Description: Chameleon relies on external libraries, such as libxml2 for XML processing. If these libraries have known vulnerabilities, an attacker can craft input that triggers those vulnerabilities, potentially leading to RCE.
    • Example: An attacker might identify a buffer overflow vulnerability in a specific version of libxml2 and then craft a malicious XML document that exploits that vulnerability when processed by Chameleon.

Attack Tree Path: 2. Exfiltrate Sensitive Data / Information Leak

• 2.1 Template Injection (Data Exposure) [HIGH RISK] [CRITICAL]
  • Description: Similar to the RCE template injection, but the attacker's goal is to extract sensitive data rather than execute code. The attacker crafts a malicious template that accesses and outputs data that should not be accessible.
  • Sub-Steps:
    • 2.1.1 Inject Malicious Template to Expose Internal Data [CRITICAL]:
      • Description: The attacker injects an XSLT template that uses features of XSLT to access and output sensitive data. This might involve accessing internal variables, reading files, or extracting data from other parts of the XML/JSON document that are not intended for public display.
      • Example: An attacker might use XPath expressions to navigate to sensitive nodes within the XML document and output their contents. Or, they might use the document() function to read and display the contents of configuration files.