CVE-2021-36301: Dell EMC iDRAC8 RCE Vulnerability

CVE-2021-36301 Overview

Dell iDRAC 9 prior to version 4.40.40.00 and iDRAC 8 prior to version 2.80.80.80 contain a Stack Buffer Overflow vulnerability in the Racadm component. An authenticated remote attacker may potentially exploit this vulnerability to control process execution and gain access to the underlying operating system. This vulnerability affects critical server management infrastructure used in enterprise data centers worldwide.

Critical Impact

Authenticated attackers can achieve remote code execution on Dell iDRAC management controllers, potentially compromising server hardware management and gaining persistent access to enterprise infrastructure.

Affected Products

• Dell EMC iDRAC9 Firmware versions prior to 4.40.40.00
• Dell EMC iDRAC8 Firmware versions prior to 2.80.80.80
• Dell PowerEdge servers utilizing affected iDRAC firmware versions

Discovery Timeline

• 2021-11-23 - CVE-2021-36301 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-36301

Vulnerability Analysis

This vulnerability is classified as a Stack Buffer Overflow (CWE-121) and Out-of-Bounds Write (CWE-787) affecting the Racadm component within Dell iDRAC firmware. The Racadm utility is a command-line interface used for remote management of Dell PowerEdge servers, providing administrators with capabilities to configure and monitor server hardware remotely.

The stack buffer overflow condition occurs when the Racadm component fails to properly validate the bounds of user-supplied input before copying it into a fixed-size stack buffer. When an authenticated attacker supplies specially crafted input that exceeds the allocated buffer size, the excess data overwrites adjacent memory on the stack, including critical control structures such as return addresses and saved frame pointers.

Root Cause

The root cause of this vulnerability lies in improper bounds checking within the Racadm command processing logic. The affected code accepts user-controlled input without adequate validation of input length, allowing data to be written beyond the boundaries of the allocated stack buffer. This is a classic memory corruption vulnerability pattern where string or data copy operations do not enforce proper length restrictions.

Attack Vector

The attack vector for CVE-2021-36301 requires network access to the iDRAC management interface and valid authentication credentials. An attacker with these prerequisites can craft malicious Racadm commands containing oversized input parameters. When processed by the vulnerable Racadm component, the input overwrites stack memory, potentially allowing the attacker to:

1. Corrupt control flow by overwriting return addresses
2. Inject and execute arbitrary shellcode
3. Gain access to the underlying iDRAC operating system
4. Establish persistent access to the server management plane

The vulnerability mechanism involves sending specially crafted input through the Racadm interface that exceeds expected buffer boundaries. When the vulnerable component processes this input without proper length validation, stack memory corruption occurs. Successful exploitation can redirect program execution to attacker-controlled code. Technical details and remediation guidance are available in the EMC Knowledge Base Article.

Detection Methods for CVE-2021-36301

Indicators of Compromise

• Unexpected or anomalous Racadm command executions with unusually long parameters
• Abnormal process crashes or restarts within the iDRAC management subsystem
• Evidence of unauthorized access to iDRAC management interfaces
• Suspicious authentication attempts followed by Racadm command activity

Detection Strategies

• Monitor iDRAC authentication logs for unusual access patterns or brute-force attempts
• Implement network intrusion detection rules to identify malformed Racadm traffic
• Deploy endpoint detection and response (EDR) solutions capable of monitoring embedded management interfaces
• Audit iDRAC firmware versions across all Dell PowerEdge servers to identify vulnerable installations

Monitoring Recommendations

• Enable comprehensive logging on all iDRAC interfaces and forward logs to a centralized SIEM
• Implement network segmentation to isolate iDRAC management traffic on dedicated VLANs
• Monitor for unexpected outbound connections from iDRAC management interfaces
• Establish baseline behavioral profiles for Racadm usage patterns to detect anomalies

How to Mitigate CVE-2021-36301

Immediate Actions Required

• Update Dell iDRAC9 firmware to version 4.40.40.00 or later immediately
• Update Dell iDRAC8 firmware to version 2.80.80.80 or later immediately
• Restrict network access to iDRAC management interfaces to trusted administrator networks only
• Review and audit all accounts with iDRAC authentication privileges

Patch Information

Dell has released firmware updates that address this vulnerability. Administrators should apply the following patches:

• iDRAC9: Update to firmware version 4.40.40.00 or later
• iDRAC8: Update to firmware version 2.80.80.80 or later

Patches and detailed update instructions are available in the EMC Knowledge Base Article. Organizations should prioritize patching based on exposure risk, with internet-facing or externally accessible iDRAC interfaces receiving immediate attention.

Workarounds

• Implement strict network access controls limiting iDRAC access to dedicated management networks
• Enable strong authentication mechanisms including multi-factor authentication where supported
• Disable unnecessary Racadm functionality if not required for operations
• Deploy firewall rules to restrict iDRAC access to specific administrator IP addresses only

# Network isolation example - restrict iDRAC access to management VLAN
# Example firewall rule to limit iDRAC access (adjust IP ranges as needed)
iptables -A INPUT -p tcp -s 10.0.100.0/24 --dport 443 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

# Verify current iDRAC firmware version via Racadm
racadm getversion