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Infrastructure 6 min read Published Updated Credibility 91/100

Infrastructure — Cisco

Cisco disclosed vulnerabilities in its Trust Anchor module affecting multiple router and switch platforms. Successful exploitation requires local access, but if you are running affected firmware, you'll want to patch before someone with physical access tries something.

Kodi C.

Editor & Research Lead

Editorially reviewed for factual accuracy

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Cisco published security advisory cisco-sa-tam-20200205 on 5 February 2020, detailing critical Trust Anchor module vulnerabilities (CVE-2019-1649 and CVE-2019-1862) that allow attackers to bypass secure boot protections and tamper with device trust chains on certain IOS XE routers and switches. These vulnerabilities undermine the hardware root of trust that protects Cisco platforms against persistent firmware implants and boot-time attacks. Organizations running affected ASR, Catalyst, and ISR platforms must focus on firmware updates and in some cases hardware replacement to restore platform integrity.

Trust Anchor Module Technology Background

The Cisco Trust Anchor module (TAm) provides hardware-based security functions including secure boot verification, hardware-anchored key storage, and firmware integrity validation. The module sets up a chain of trust from hardware through bootloader and operating system, ensuring that only authorized and unmodified code executes on the platform.

Secure boot setups rely on Trust Anchor modules to verify cryptographic signatures on firmware images before allowing execution. This protection prevents attackers from installing persistent malware that survives device reboots or operating system reinstallation. Without functioning Trust Anchor protections, devices become vulnerable to firmware-level rootkits and implants.

Trust Anchor modules also support cryptographic operations including key generation, storage, and digital signing. Compromise of Trust Anchor functionality could expose private keys or enable signature forgery affecting device authentication and encrypted communications.

Technical details

CVE-2019-1649 affects the Secure Boot setup in certain Cisco devices, allowing authenticated local attackers to write modified firmware images to the component that stores bootloader data. Successful exploitation enables attackers to bypass secure boot verification and load unauthorized firmware that executes with full platform privileges.

CVE-2019-1862 allows authenticated remote attackers with administrator privileges to execute arbitrary commands on the underlying Linux shell of affected devices. While requiring administrative access, this vulnerability enables privilege escalation beyond intended administrative capabilities and could help Trust Anchor manipulation.

Exploitation of these vulnerabilities requires either local access or authenticated administrative access, limiting exposure compared to unauthenticated remote attacks. However, the severity stems from the persistent nature of compromise—attackers achieving Trust Anchor manipulation create implants that survive remediation attempts not addressing the firmware level.

Attack chains might combine these vulnerabilities with credential theft or other privilege escalation techniques to achieve hardware-level persistence on network infrastructure devices.

Affected Products and Platforms

The vulnerabilities affect multiple Cisco product families running IOS XE software. ASR 1000 Series Aggregation Services Routers used in enterprise and service provider edge deployments are affected. Catalyst 3850 and 9000 series switches commonly deployed in campus and data center environments require assessment.

ISR 4000 Series Integrated Services Routers serving branch office and WAN edge functions contain vulnerable Trust Anchor setups. Cisco Nexus data center switches and other platforms may be affected depending on hardware revision and software version combinations.

Hardware component variations affect vulnerability status—devices with specific FPGA or ASR1000-RP component revisions may require different remediation approaches. Organizations must cross-reference device serial numbers and component versions against Cisco's affected product tables to determine specific remediation requirements.

Some hardware revisions cannot be remediated through software updates alone and require physical component replacement. Cisco TAC engagement may be necessary to identify replacement options and coordinate logistics.

Impact on Network Security Architecture

Trust Anchor compromise undermines fundamental assumptions about network device integrity that security architectures rely upon. Secure boot bypass enables attackers to install persistent backdoors undetectable through operating system-level inspection. Network monitoring and configuration management tools cannot detect firmware-level modifications.

Edge and core infrastructure devices present high-value targets for advanced threat actors. Routers and switches process all network traffic passing through infrastructure segments, enabling traffic interception, modification, or redirection. Firmware-level access provides attackers with visibility and control that application-layer compromises cannot achieve.

Nation-state actors have showed interest in network infrastructure compromise for intelligence collection and pre-positioning for potential future operations. The persistent nature of firmware implants makes them particularly valuable for long-term access maintenance.

Incident response procedures assuming operating system reinstallation removes persistent threats are invalidated by Trust Anchor compromise. Recovery from suspected firmware-level compromise may require hardware replacement or specialized forensic procedures.

Remediation and Mitigation Strategy

Primary remediation requires applying software and ROMMON (Read-Only Memory Monitor) updates that address the vulnerabilities. Cisco provides fixed software releases specific to affected platforms—organizations must identify correct releases for their hardware configurations. ROMMON updates require careful execution with verified recovery procedures to avoid bricking devices.

Maintenance window planning must account for extended downtime potentially required for ROMMON updates. Out-of-band management access ensures recovery capability if updates encounter problems. Backup configurations and software images before beginning remediation activities.

Hardware replacement is required where software patches cannot address the vulnerability due to component limitations. Cisco TAC can assist in identifying replacement requirements and coordinating logistics. Budget and procurement planning should anticipate potential hardware costs.

Post-remediation validation should verify secure boot status and run integrity checks using commands like 'secure boot verify' to confirm Trust Anchor module enforcement. Baseline trust state documentation supports future integrity monitoring.

  • Cross-check hardware inventories against affected product tables in the Cisco advisory, prioritizing ASR, Catalyst, and ISR platforms running IOS XE.
  • Identify specific hardware component revisions to determine whether software-only or hardware replacement remediation is required.
  • Schedule maintenance windows for ROMMON and software upgrades with appropriate change control and recovery procedures.
  • Ensure out-of-band management access for recovery if updates encounter problems.
  • Engage Cisco TAC for hardware replacement coordination where patches are unavailable.
  • Validate trust state after updates using secure boot verification commands and integrity checks.
  • Document baseline trust state for ongoing integrity monitoring and future incident response.
  • Review network architecture for devices with highest value as attack targets and focus on as needed.

Assessment

The Trust Anchor vulnerabilities represent a particularly concerning class of infrastructure security issue because they target the foundational trust mechanisms that security architectures rely upon. If you are affected, use this disclosure as an opportunity to evaluate firmware integrity monitoring capabilities across their network infrastructure.

Establishing baseline trust states and implementing ongoing integrity validation provides defense-in-depth against both known vulnerabilities and potential future firmware-level threats. The complexity of remediation involving both software updates and potential hardware replacement highlights the importance of preventive infrastructure security investment and vendor lifecycle management planning.

Hardware Root of Trust Vulnerabilities

When your hardware security foundation has vulnerabilities, everything built on top becomes questionable. Cisco's Trust Anchor is meant to be the bedrock of device security—a vulnerability here has implications that ripple through your entire network.

This is not the kind of vulnerability you can patch and forget. It requires careful assessment of which devices are affected and what level of risk you are willing to accept.

Making Hard Decisions

Sometimes security advisories require you to make uncomfortable choices. Replacing hardware is expensive; living with known vulnerabilities is risky. There is no easy answer, only informed tradeoffs.

Document your risk acceptance decisions carefully. If you choose to continue using affected devices, understand exactly what risks you are taking on and implement compensating controls where possible.

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Coverage intelligence

Published
Coverage pillar
Infrastructure
Source credibility
91/100 — high confidence
Topics
Cisco · IOS XE · Trust Anchor · Secure Boot
Sources cited
3 sources (tools.cisco.com, cisa.gov, csrc.nist.gov)
Reading time
6 min

Documentation

  1. Cisco Security Advisory — Cisco
  2. CISA Advisory — CISA
  3. NIST Firmware Security — NIST
  • Cisco
  • IOS XE
  • Trust Anchor
  • Secure Boot
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