Cisco's IOS XE: Urgent Alert


Published on Oct 17, 2023   —   2 min read

In the cybersecurity arena, vigilance is non-negotiable. Cisco's recent critical security advisory serves as a reminder of this reality. The advisory pertains to a severe privilege escalation vulnerability in the Web UI feature of Cisco's IOS XE Software. With active exploitation confirmed, immediate action is imperative. Let's dissect the advisory and discuss risk mitigation strategies.

The Advisory Unpacked

Designated as CVE-2023-20198, this vulnerability enables a remote, unauthorized attacker to create an elevated-privilege account on the targeted system. To put it bluntly, it's akin to an open invitation to compromise your network. The vulnerability has earned a CVSS score of 10.0, indicating the highest level of risk.

Why This Matters

The Web UI feature is commonly enabled for administrative convenience, leaving a multitude of devices vulnerable. Adding to the gravity of the situation is the absence of any available workarounds. Cisco's sole recommendation is to disable the HTTP Server feature on systems exposed to the internet.

Real-world Consequences

Consider the ramifications if an attacker gains control of a router within a critical infrastructure network. The fallout could range from massive data breaches to the crippling of essential services.

Cisco's guidance is unequivocal: disable the HTTP Server feature by executing the no ip http server or no ip http secure-server commands in global configuration mode. If your setup requires HTTP/HTTPS communication, limit access to trusted networks.

Decision Matrix for Immediate Measures

  1. Running IOS XE?
    • No: You're in the clear. No action required.
    • Yes: Continue to the next step.
  2. Is ip http server or ip http secure-server active?
    • No: You're secure. No action required.
    • Yes: Deactivate the HTTP Server feature or restrict access.

Indicators to Watch

Cisco has provided detailed indicators of compromise, which are crucial for identifying whether your system has been affected. Here's where you can find them:

  1. System Logs: Accessible through your device's management interface or its operating system, system logs will contain specific messages that indicate a compromise. Look for unfamiliar usernames or unexpected file activities.
  2. Snort Rule IDs: If you're using Snort for intrusion detection, implement the following rule IDs that Cisco has provided to detect exploitation attempts:
    • 3:50118:2 - Alerts for initial implant injection
    • 3:62527:1 - Alerts for implant interaction
    • 3:62528:1 - Alerts for implant interaction
    • 3:62529:1 - Alerts for implant interaction

By actively monitoring these indicators, you're not just waiting for the storm to pass; you're learning how to dance in the rain, cybersecurity style.

Awaiting Updates

Cisco is actively investigating and has committed to releasing a software patch. Stay tuned for updates.


This Cisco advisory serves as a dual-purpose alarm bell: it's both a call to immediate action and an impetus for a broader reevaluation of your cybersecurity stance. In a field where threats evolve rapidly, a proactive defense is not a luxury but a necessity. This means not just patching known vulnerabilities but also fostering a culture of security awareness and regularly auditing your systems.

The advisory should also prompt organizations to scrutinize their vendor selection criteria, the comprehensiveness of their security audits, and the readiness of their incident response plans. In essence, while addressing this specific vulnerability is urgent, it's equally crucial to use this as a catalyst for strengthening your overall cybersecurity infrastructure.

Quick Fact

The vulnerability was unearthed during the resolution of multiple Cisco TAC support cases—a needle in a haystack, indeed.

Source: Cisco Security Advisory

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