Detecting browser anomalies to disrupt attacks early

Detecting browser anomalies is critical to early identification and prevention of cyber threats, and prevents data breaches and attacks by monitoring unexpected browser activity. Browser anomaly detection can help prevent attackers from impersonating legitimate users by uncovering unusual session activity. It helps identify unauthorized interception of session cookies that can be used to access user credentials during man-in-the-middle attacks. By responding quickly to these early activities, organizations can effectively remediate potential security incidents and strengthen their overall security posture. Microsoft Defender XDR provides a range of detection capabilities that detect browser anomalies and automatically stop attacks.

Automatic Attack Blocking with Microsoft Defender XDR Minimize the impact on your organization’s assets by stopping an ongoing attack, isolating compromised assets, and giving your security team more time to fully remediate the incident. By stopping an attack early, you help prevent the threat from spreading and reduce the broader impact, such as associated financial costs and lost productivity.

This blog post provides insights into how to leverage browser anomalies and malicious login traits to disrupt attacks in their early stages and prevent attackers from achieving their goals.

Browser-related information (e.g., user agent string) serves as an identifier to determine the browser type, version, and operating system used by the client. Detecting anomalies in browser usage can be instrumental in identifying malicious activity. For example, unexpected access to a user account from a different browser or distant geographical location may indicate that the account has been compromised. Monitoring changes in browser usage is also essential in detecting instances such as: Session Hijacking – When an attacker gains control of a user’s session after the user has been authenticated. Session hijacking attacks result in the following very important attack vectors: Multi-level AiTM phishing, Business Email Compromise (BEC)), and persistence By creating an OAuth application. To maintain session integrity, you must ensure consistency of user properties, including browser properties. Sudden changes to these properties can represent a potential security threat.

Identifying potential threats and anomalous activities through browser anomalies requires a thorough analysis of patterns and inconsistencies observed in browser-related information, such as user agent strings during user login events. Relying solely on browser-related information inconsistencies may not provide sufficient context to identify anomalies. Ensuring effective detection typically involves correlating browser-related information with additional behavioral and environmental data. Microsoft Defender XDR We use a variety of techniques to detect browser anomalies by leveraging strong signals. Microsoft Entra To boost your confidence.

A systematic approach to detecting browser anomalies is as follows:

• Data collection – We collect data from user login activities, focusing on browser-related information such as user agent string, operating system, browser cookies, session ID, IP address, and location.
• Setting the baseline – Analyze historical data to identify common patterns in browser usage, location, and IP addresses to create a baseline profile of expected behavior for users or groups, then flag deviations based on heuristic analysis.
• Real-time monitoring and anomaly detection – Entra ID Protection continuously monitors and detects anomalies in real time before, during, and after a login session using UEBA and machine learning algorithms. Implement to strengthen your security posture. RBCA Policy Integrates with Defender XDR to proactively assess risks such as browser switching, unusual browsers or user agents, and regional inconsistencies.
• Threat Intelligence Correlation – Strengthen detection capabilities by analyzing past attack patterns and monitoring infrastructure of known threat actors. Focus on user agent strings associated with known threats or strings observed in previous real-world attacks.

Leveraging these high-confidence signals from Entra ID, Defender XDR offers several detectors that identify high-confidence browser anomalies. These detectors are enabled for: Auto attack interrupt. Attack interference Disable corrupted user accounts. Prevents attacks from progressing across both Active Directory and Entra ID.

Below is a list of detections that automatically thwart attacks based on browser anomalies..

Here is a real-world example of how these detectors can stop an attack from progressing early. split.

Figure 1. Blocking attack progression as quickly as possible based on browser anomaly detection.

The Business Email Compromise (BEC) attack began with a malicious login to Office Home using a browser anomaly, which then led to account compromise and phishing attacks. Defender XDR stops the attack early in the kill chain based on widespread signals and anomaly detection, halting its progression without SOC intervention.

Microsoft’s XDR effectively blocks attacks, thwarting attackers’ objectives.

Figure 2. Example of a blocked incident due to a user interrupt with an attack interrupt tag.

You can configure automatic attack termination to give the SOC team full control. All operations can be easily undone In the security portal.

Get started

1. Make sure your organization meets the following: Microsoft Defender XDR Prerequisites

1. Connect Microsoft Defender for Cloud Apps
2. Deploying Microsoft Entra ID Protection.
3. Deploying Defender for Endpoint. A free trial is available. here.
4. Deploying Microsoft Defender for Identity.

Intermediate Adversary (AiTM) Supports automatic attack interruption