CVE-2023-46217: Ivanti Avalanche DoS Vulnerability

CVE-2023-46217 Overview

CVE-2023-46217 is a critical memory corruption vulnerability affecting Ivanti Avalanche, an enterprise mobility management solution. An attacker sending specially crafted data packets to the Mobile Device Server can cause memory corruption which could result in a Denial of Service (DoS) or code execution. This out-of-bounds write vulnerability (CWE-787) allows unauthenticated remote attackers to potentially compromise the affected system without any user interaction.

Critical Impact

This vulnerability enables unauthenticated remote attackers to send malicious network packets that can corrupt memory, potentially leading to arbitrary code execution or complete denial of service on Ivanti Avalanche Mobile Device Server deployments.

Affected Products

• Ivanti Avalanche (versions prior to 6.4.2)
• Ivanti Avalanche On-Premise deployments
• Microsoft Windows systems running affected Avalanche versions

Discovery Timeline

• 2023-12-19 - CVE-2023-46217 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-46217

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-bounds Write), a memory corruption flaw that occurs when an application writes data past the allocated boundary of a buffer. In the context of Ivanti Avalanche's Mobile Device Server, the vulnerability exists in the processing of network packets, where insufficient validation of input data allows attackers to trigger memory corruption conditions.

Out-of-bounds write vulnerabilities are particularly dangerous because they can be leveraged for multiple attack scenarios. An attacker can potentially overwrite critical memory structures, crash the application causing denial of service, or in more sophisticated attacks, achieve arbitrary code execution by carefully crafting the malicious payload to overwrite function pointers or return addresses.

Root Cause

The root cause of CVE-2023-46217 is improper bounds checking in the Mobile Device Server component when processing incoming network packets. The server fails to properly validate the size or structure of certain data fields within packets before writing them to memory buffers. This lack of input validation enables an attacker to send oversized or malformed data that writes beyond the intended memory allocation, corrupting adjacent memory regions.

Attack Vector

The attack vector for this vulnerability is network-based, requiring no authentication or user interaction. An attacker can remotely send specially crafted packets to the Mobile Device Server's listening port. The attack can be executed from any network location that can reach the target server, making internet-exposed Avalanche deployments particularly vulnerable. The attack does not require any privileges, credentials, or prior access to the target system.

The exploitation flow involves crafting malicious network packets that contain data designed to trigger the out-of-bounds write condition when processed by the vulnerable server component. Successful exploitation can result in immediate denial of service through application crash or, with more sophisticated payloads, potential remote code execution in the context of the Avalanche service.

Detection Methods for CVE-2023-46217

Indicators of Compromise

• Unexpected crashes or service restarts of Ivanti Avalanche Mobile Device Server
• Anomalous network traffic patterns targeting Avalanche server ports with malformed or oversized packets
• Memory corruption evidence in crash dumps or error logs from the Mobile Device Server component
• Unusual process behavior or child processes spawned by Avalanche services indicating potential code execution

Detection Strategies

• Monitor Ivanti Avalanche services for unexpected crashes, restarts, or high memory utilization that could indicate exploitation attempts
• Implement network intrusion detection rules to identify malformed packets targeting Avalanche Mobile Device Server ports
• Review Windows Event Logs for application errors related to Avalanche components, particularly memory access violations
• Deploy endpoint detection and response (EDR) solutions to monitor for anomalous behavior from Avalanche processes

Monitoring Recommendations

• Enable verbose logging on Ivanti Avalanche servers to capture detailed information about incoming connections and packet processing
• Configure alerts for service availability to detect denial of service conditions early
• Monitor network traffic to Avalanche servers for unusual packet sizes or frequencies that may indicate scanning or exploitation attempts

How to Mitigate CVE-2023-46217

Immediate Actions Required

• Upgrade Ivanti Avalanche to version 6.4.2 or later immediately to address this vulnerability
• Restrict network access to the Mobile Device Server to trusted networks and IP ranges using firewall rules
• Implement network segmentation to isolate Avalanche servers from untrusted network segments
• Monitor Avalanche servers closely for signs of exploitation until patching is complete

Patch Information

Ivanti has released version 6.4.2 of Avalanche which addresses this vulnerability. Organizations should apply this update as soon as possible. Detailed release notes and download information are available from the Wavelink Avalanche Release Notes. The patch corrects the memory handling issue by implementing proper bounds checking for incoming network packet data.

Workarounds

• Implement strict firewall rules to limit access to Avalanche Mobile Device Server ports only from known, trusted mobile device networks
• Deploy web application firewalls (WAF) or intrusion prevention systems (IPS) with rules to detect and block malformed packets
• Consider temporarily disabling external network access to Avalanche servers until patches can be applied in critical environments
• Use network access control lists (ACLs) to restrict which IP addresses can communicate with the Mobile Device Server component

# Example: Restrict access to Avalanche server using Windows Firewall
# Replace AVALANCHE_PORT with your Mobile Device Server port
# Replace TRUSTED_NETWORK with your authorized network range
netsh advfirewall firewall add rule name="Block Avalanche External" dir=in action=block protocol=tcp localport=AVALANCHE_PORT
netsh advfirewall firewall add rule name="Allow Avalanche Trusted" dir=in action=allow protocol=tcp localport=AVALANCHE_PORT remoteip=TRUSTED_NETWORK/24