CVE-2022-23011: F5 BIG-IP Access Policy Manager DoS Flaw

CVE-2022-23011 Overview

CVE-2022-23011 is a Denial of Service (DoS) vulnerability affecting F5 BIG-IP hardware platforms. On certain hardware BIG-IP platforms, in version 15.1.x before 15.1.4 and 14.1.x before 14.1.3, virtual servers may stop responding while processing TCP traffic due to an issue in the SYN Cookie Protection feature. This vulnerability allows remote attackers to disrupt service availability without requiring authentication or user interaction.

Critical Impact

Virtual servers on affected BIG-IP hardware platforms can become unresponsive when processing TCP traffic, potentially causing complete service disruption for applications relying on F5 load balancing and application delivery infrastructure.

Affected Products

• F5 BIG-IP Access Policy Manager (versions 14.1.x before 14.1.3, 15.1.x before 15.1.4)
• F5 BIG-IP Advanced Firewall Manager (versions 14.1.x before 14.1.3, 15.1.x before 15.1.4)
• F5 BIG-IP Local Traffic Manager (versions 14.1.x before 14.1.3, 15.1.x before 15.1.4)
• F5 BIG-IP Application Security Manager (versions 14.1.x before 14.1.3, 15.1.x before 15.1.4)
• F5 BIG-IP Hardware Platforms: i850, i2600, i2800

Discovery Timeline

• January 25, 2022 - CVE-2022-23011 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2022-23011

Vulnerability Analysis

This vulnerability is categorized under CWE-682 (Incorrect Calculation), indicating that the SYN Cookie Protection feature performs faulty computations when processing TCP traffic on specific hardware platforms. The vulnerability is exploitable remotely over the network without requiring any authentication or user interaction. Successful exploitation results in a complete denial of service condition affecting virtual server availability.

The SYN Cookie Protection mechanism is designed to protect against SYN flood attacks by encoding connection state information in the sequence number of SYN-ACK packets. However, an incorrect calculation within this feature on affected hardware platforms causes the virtual servers to become unresponsive when processing certain TCP traffic patterns.

Root Cause

The root cause lies in an incorrect calculation (CWE-682) within the SYN Cookie Protection feature implementation on specific BIG-IP hardware platforms. When the affected hardware processes TCP traffic under certain conditions, the faulty computation causes the Traffic Management Microkernel (TMM) to enter an unresponsive state. This defect is specific to the i850, i2600, and i2800 hardware platforms running vulnerable software versions.

Attack Vector

The attack vector is network-based, requiring no privileges or user interaction. An attacker can exploit this vulnerability by sending crafted TCP traffic to virtual servers configured on vulnerable BIG-IP hardware platforms. The SYN Cookie Protection feature, when engaged while processing this traffic, triggers the incorrect calculation that causes the virtual server to stop responding.

The vulnerability affects application delivery and load balancing services, meaning exploitation could impact all backend applications relying on the affected BIG-IP infrastructure for traffic management.

Detection Methods for CVE-2022-23011

Indicators of Compromise

• Virtual servers becoming unresponsive or unavailable without apparent cause
• TMM (Traffic Management Microkernel) process exhibiting abnormal behavior or restarts
• Sudden drops in throughput on affected BIG-IP hardware platforms
• Increased connection timeouts reported by clients accessing services through BIG-IP

Detection Strategies

• Monitor BIG-IP system logs for TMM-related errors or unexpected restarts on i850, i2600, and i2800 platforms
• Implement network monitoring to detect unusual TCP traffic patterns targeting BIG-IP virtual servers
• Configure SNMP traps for virtual server availability status changes
• Review BIG-IP statistics for sudden drops in connections per second metrics

Monitoring Recommendations

• Enable detailed logging for the SYN Cookie Protection feature to identify when it activates
• Set up real-time alerting for virtual server health status on affected hardware platforms
• Monitor TMM CPU and memory utilization for anomalies that may precede service disruption
• Implement synthetic monitoring to proactively detect virtual server availability issues

How to Mitigate CVE-2022-23011

Immediate Actions Required

• Identify all BIG-IP hardware platforms in your environment, specifically i850, i2600, and i2800 models
• Review current software versions on affected hardware and prioritize patching if running versions 14.1.x before 14.1.3 or 15.1.x before 15.1.4
• Assess the business impact of potential virtual server disruption and plan maintenance windows accordingly
• Review F5 support article K68755210 for additional vendor guidance

Patch Information

F5 has addressed this vulnerability in BIG-IP versions 15.1.4 and 14.1.3. Organizations running affected hardware platforms should upgrade to these patched versions or later. Detailed patch information and upgrade procedures are available in the F5 Support Article K68755210.

Note: Software versions that have reached End of Technical Support (EoTS) are not evaluated and may remain vulnerable without available patches.

Workarounds

• Consult F5 support article K68755210 for any available temporary mitigations while planning upgrades
• Consider implementing additional DDoS protection layers upstream of affected BIG-IP devices
• Evaluate traffic management configurations to reduce load on affected hardware during peak periods
• If possible, migrate critical workloads to non-affected hardware platforms until patching is complete

# Check current BIG-IP software version
tmsh show sys version

# Verify hardware platform model
tmsh show sys hardware | grep -i "platform"

# Review SYN Cookie Protection status
tmsh show ltm virtual all | grep -i "syn"