GraphRunner: A Deep Dive into its Functions, Features, and Use Cases
Understanding the Microsoft Graph API
Before diving into GraphRunner, it’s essential to understand its foundation: the Microsoft Graph API. This API serves as a unified gateway to access data across various Microsoft 365 services. Think of it as a single point of entry to interact with:
Microsoft Entra ID (formerly Azure AD): Manages identities and access.
Exchange Online: Handles email and calendaring.
SharePoint: Facilitates document management and collaboration.
Teams: Enables communication and teamwork.
OneDrive: Provides cloud storage.
The Graph API empowers developers to build integrated applications, streamline workflows, and access critical organizational data. However, this powerful tool can also be exploited by malicious actors if not properly secured.
Introducing GraphRunner
GraphRunner, developed by Beau Bullock of Black Hills Information Security, is a PowerShell-based post-exploitation tool designed to leverage the Microsoft Graph API in potentially harmful ways you can find the tool at https://github.com/dafthack/GraphRunner/
What is Post-Exploitation?
In cybersecurity, post-exploitation refers to the actions an attacker takes after gaining initial access to a system or network. Instead of focusing on getting in, GraphRunner focuses on what an attacker can do once they’re in.
GraphRunner’s Core Functions and Features
GraphRunner equips attackers (and red teamers simulating attacks) with a range of capabilities, including:
** Reconnaissance:**
Invoke-GraphRecon: This module is used to gather information about the target environment. This includes details about users, groups, applications, and their associated permissions. Attackers use this to map out the organization’s structure and identify potential vulnerabilities.
** Data Exfiltration:**
GraphRunner can extract sensitive data from various Microsoft 365 services. This could include:
Emails from Exchange Online
Files from SharePoint and OneDrive
Potentially sensitive information from Teams
** Persistence:**
Attackers often seek to maintain access to a compromised system, even if credentials change. GraphRunner provides modules to establish persistence mechanisms, allowing them to return to the environment later.
** Privilege Escalation:**
GraphRunner can be used to attempt to elevate an attacker’s privileges within the organization. By gaining higher-level access, attackers can access more sensitive data and systems.
** Enumeration:**
GraphRunner helps in discovering resources and settings within the Microsoft 365 tenant. This allows attackers to understand the scope of their access and identify potential targets.
Use Cases for GraphRunner
** Red Teaming:**
Security teams use GraphRunner to simulate real-world attacks in a controlled environment. This helps them:
Identify weaknesses in their Microsoft 365 configurations.
Test the effectiveness of their security controls.
Improve their incident response capabilities.
** Adversary Simulation:**
By understanding how attackers use GraphRunner, defenders can:
Anticipate potential attack vectors.
Develop specific detection strategies.
Harden their systems to prevent real-world attacks.
** Vulnerability Research:**
Security researchers may use GraphRunner to identify and analyze vulnerabilities in the Microsoft Graph API and related Microsoft 365 services.
How GraphRunner Works: A Technical Overview
GraphRunner is a PowerShell-based tool, meaning it leverages the PowerShell scripting language to automate interactions with the Microsoft Graph API.
The general workflow involves:
** Authentication:** GraphRunner needs to authenticate to the Microsoft Graph API to access data. This typically involves obtaining access tokens, which grant the tool the necessary permissions.
** API Calls:** GraphRunner uses PowerShell scripts to construct and send API requests to the Microsoft Graph API. These requests specify the desired actions, such as retrieving user information, downloading files, or modifying permissions.
** Data Processing:** The Microsoft Graph API responds to GraphRunner’s requests with data, which GraphRunner then processes and presents to the user (or attacker).
Defensive Implications
GraphRunner highlights the importance of securing the Microsoft Graph API and Microsoft 365 environments. Security teams should:
** Implement strong authentication:** Use multi-factor authentication (MFA) to make it more difficult for attackers to gain initial access.
** Apply the principle of least privilege:** Grant users and applications only the necessary permissions.
** Monitor Graph API activity:** Keep a close eye on Graph API logs for suspicious patterns, such as:
Unusual API calls
Excessive requests
Access to sensitive data by unauthorized accounts
** Regularly review application permissions:** Ensure that applications connected to the Graph API have only the permissions they need.
** Harden Microsoft 365 configurations:** Implement security best practices for Microsoft 365 services.
Conclusion
GraphRunner is a powerful tool that underscores the potential risks associated with the Microsoft Graph API. While it can be used for malicious purposes, it also provides valuable insights for security teams. By understanding how GraphRunner works and the tactics it employs, defenders can take proactive steps to protect their Microsoft 365 environments and mitigate the risk of attack.
Remember these tools are to be used on approved systems only