CVE-2024-6327: Telerik Report Server RCE Vulnerability

CVE-2024-6327 Overview

CVE-2024-6327 is a critical insecure deserialization vulnerability affecting Progress® Telerik® Report Server versions prior to 2024 Q2 (10.1.24.709). This vulnerability allows remote attackers to achieve code execution through maliciously crafted serialized objects, potentially leading to complete system compromise without requiring authentication.

Critical Impact

Remote code execution through insecure deserialization enables attackers to execute arbitrary commands on vulnerable Telerik Report Server instances, potentially compromising sensitive business intelligence data and gaining persistent access to internal networks.

Affected Products

• Progress Telerik Report Server versions prior to 10.1.24.709 (2024 Q2)
• All earlier Telerik Report Server releases with vulnerable deserialization components

Discovery Timeline

• 2024-07-24 - CVE-2024-6327 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-6327

Vulnerability Analysis

This vulnerability falls into the category of insecure deserialization (CWE-502), a well-documented class of security flaws where untrusted data is passed to deserialization functions without proper validation. In the context of Telerik Report Server, the application accepts serialized .NET objects over the network that can be manipulated by attackers to execute arbitrary code during the deserialization process.

The vulnerability is particularly dangerous because it requires no authentication and can be exploited remotely over the network with low attack complexity. A successful exploit grants the attacker complete control over the affected server, including the ability to read, modify, or delete data, install malware, or use the compromised system as a pivot point for further attacks within the network.

Root Cause

The root cause of CVE-2024-6327 is insufficient validation of serialized object data before deserialization. The Telerik Report Server fails to properly restrict which object types can be instantiated during the deserialization process, allowing attackers to inject malicious object graphs that execute code when processed.

.NET deserialization vulnerabilities typically exploit gadget chains—sequences of existing classes in the application or framework that, when combined, result in arbitrary code execution. Attackers craft payloads containing these gadget chains that trigger dangerous operations such as process execution or file system access when the server deserializes the malicious input.

Attack Vector

The attack vector for this vulnerability is network-based, meaning attackers can exploit it remotely without physical access to the target system. The exploitation flow typically involves:

1. An attacker identifies a Telerik Report Server instance exposed to the network
2. The attacker crafts a malicious serialized payload containing a gadget chain designed for code execution
3. The payload is sent to a vulnerable endpoint that processes serialized data
4. When the server deserializes the payload, the gadget chain executes, running the attacker's commands with the privileges of the Report Server process

The vulnerability requires no user interaction and no prior authentication, making it highly exploitable in environments where Telerik Report Server is accessible over the network. For detailed technical information, refer to the official Telerik security advisory.

Detection Methods for CVE-2024-6327

Indicators of Compromise

• Unusual process spawning from the Telerik Report Server application process (e.g., cmd.exe, powershell.exe, or other shell processes)
• Unexpected outbound network connections from the Report Server to external IP addresses
• Creation of new files or modifications to system files in the Report Server installation directory
• Authentication failures followed by successful command execution without legitimate login events
• Anomalous HTTP POST requests containing Base64-encoded or binary serialized data to Report Server endpoints

Detection Strategies

• Deploy network intrusion detection signatures targeting known .NET deserialization exploit patterns in HTTP traffic
• Implement application-level logging to capture all deserialization events and monitor for suspicious object types
• Use endpoint detection and response (EDR) solutions like SentinelOne to detect anomalous child process creation from the Report Server service
• Monitor Windows Event Logs for process creation events (Event ID 4688) where the parent process is the Telerik Report Server

Monitoring Recommendations

• Establish baseline network traffic patterns for Telerik Report Server and alert on deviations
• Configure file integrity monitoring on the Report Server installation directory and system directories
• Implement real-time monitoring of PowerShell and command-line activity on servers hosting Telerik Report Server
• Enable enhanced process auditing and correlate events with network activity for comprehensive threat detection

How to Mitigate CVE-2024-6327

Immediate Actions Required

• Upgrade Telerik Report Server to version 10.1.24.709 (2024 Q2) or later immediately
• If immediate patching is not possible, restrict network access to Telerik Report Server to trusted IP addresses only
• Review server logs for any signs of exploitation attempts or successful compromise
• Implement network segmentation to isolate Report Server instances from critical infrastructure

Patch Information

Progress has released version 10.1.24.709 (2024 Q2) of Telerik Report Server which addresses this insecure deserialization vulnerability. Organizations should upgrade to this version or later as soon as possible. Detailed patching instructions and release notes are available in the official Telerik CVE-2024-6327 advisory.

Workarounds

• Implement Web Application Firewall (WAF) rules to block requests containing serialized .NET object patterns
• Restrict access to the Telerik Report Server to internal networks only using firewall rules or VPN requirements
• Disable any unused endpoints or services on the Report Server to reduce the attack surface
• Apply the principle of least privilege to the service account running Telerik Report Server to limit post-exploitation impact

# Example: Restrict Telerik Report Server access via Windows Firewall
# Allow only specific trusted IP ranges to access the Report Server port
netsh advfirewall firewall add rule name="Restrict Telerik Report Server" ^
    dir=in action=allow protocol=tcp localport=83 ^
    remoteip=10.0.0.0/8,192.168.0.0/16
netsh advfirewall firewall add rule name="Block Telerik Report Server External" ^
    dir=in action=block protocol=tcp localport=83