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MS-ISAC CYBERSECURITY ADVISORY
MS-ISAC ADVISORY NUMBER:
2023-122 – UPDATED
DATE(S) ISSUED:
10/16/2023
10/27/2023 – UPDATED
SUBJECT:
A Vulnerability in Cisco IOS XE Software Web UI Could Allow for Privilege Escalation
OVERVIEW:
A vulnerability in Cisco IOS XE Software Web UI that could allow for privilege escalation. Successful exploitation could allow an unauthenticated remote attacker to create an account on an affected system with privilege level 15 access, allowing them to use that account to gain control of the affected system. The Cisco IOS XE Software web UI is an embedded GUI-based system-management tool, that comes with the default image.
THREAT INTELLIGENCE:
Cisco is aware of this vulnerability being exploited in the wild.
SYSTEMS AFFECTED:
- This vulnerability affects Cisco IOS XE Software if the web UI feature is enabled.
October 27th – UPDATED SYSTEMS AFFECTED:
- Cisco IOS XE Software Releases prior to 17.9.4a
- Cisco IOS XE Software Releases prior to 17.6.6a
- Cisco IOS XE Software Releases prior to 17.3.8a
- Cisco IOS XE Software Releases prior to 16.12.10a
RISK:
Government:
- Large and medium government entities: High
- Small government entities: High
Businesses:
- Large and medium business entities: High
- Small business entities: High
Home users: Low
TECHNICAL SUMMARY:
A vulnerability has been discovered in Cisco IOS XE Software Web UI that could allow for privilege escalation.
According to Cisco, at this time a patch is not available, and there are no workarounds that address this vulnerability. As a defensive measure it is strongly recommended that users disable the HTTP Server feature on all internet-facing systems.
Tactic: Credential Access (TA0006):
Technique: Unsecured Credentials (T1552):
- A vulnerability in Cisco IOS XE Software Web UI that could allow for privilege escalation and if exploited could allow an unauthenticated, remote attacker to create an account on an affected system with privilege level 15 access allowing them to use that account to gain control of the affected system.
October 27th – UPDATED TECHNICAL SUMMARY:
Cisco has released appropriate fixed software releases relating to the vulnerability. They do advise that customers upgrade to a fixed version.
For detailed platform release information, see:
https://www.cisco.com/c/en/us/support/docs/ios-nx-os-software/ios-xe-dublin-17121/221128-software-fix-availability-for-cisco-ios.html
For versions that do not have a patch available, Cisco does offer work arounds within the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-webui-privesc-j22SaA4z
RECOMMENDATIONS:
We recommend the following actions be taken:
- Apply appropriate updates and patches provided by Cisco to vulnerable systems immediately after appropriate testing. (M1051: Update Software)
- Safeguard 7.1: Establish and Maintain a Vulnerability Management Process: Establish and maintain a documented vulnerability management process for enterprise assets. Review and update documentation annually, or when significant enterprise changes occur that could impact this Safeguard.
- Safeguard 7.4: Perform Automated Application Patch Management: Perform application updates on enterprise assets through automated patch management on a monthly, or more frequent, basis.
- Safeguard 7.5: Perform Automated Vulnerability Scans of Internal Enterprise Assets: Perform automated vulnerability scans of internal enterprise assets on a quarterly, or more frequent, basis. Conduct both authenticated and unauthenticated scans, using a SCAP-compliant vulnerability scanning tool.
- Apply the Principle of Least Privilege to all systems and services. Run all software as a non-privileged user (one without administrative privileges) to diminish the effects of a successful attack. (M1026: Privileged Account Management)
- Safeguard 4.7: Manage Default Accounts on Enterprise Assets and Software: Manage default accounts on enterprise assets and software, such as root, administrator, and other pre-configured vendor accounts. Example implementations can include: disabling default accounts or making them unusable.
- Safeguard 5.4: Restrict Administrator Privileges to Dedicated Administrator Accounts: Restrict administrator privileges to dedicated administrator accounts on enterprise assets. Conduct general computing activities, such as internet browsing, email, and productivity suite use, from the user’s primary, non-privileged account.
- Block execution of code on a system through application control, and/or script blocking. (M1038: Execution Prevention)
- Safeguard 2.5 : Allowlist Authorized Software: Use technical controls, such as application allowlisting, to ensure that only authorized software can execute or be accessed. Reassess bi-annually, or more frequently.
- Safeguard 2.6 : Allowlist Authorized Libraries: Use technical controls to ensure that only authorized software libraries, such as specific .dll, .ocx, .so, etc., files, are allowed to load into a system process. Block unauthorized libraries from loading into a system process. Reassess bi-annually, or more frequently.
- Safeguard 2.7 : Allowlist Authorized Scripts: Use technical controls, such as digital signatures and version control, to ensure that only authorized scripts, such as specific .ps1, .py, etc., files, are allowed to execute. Block unauthorized scripts from executing. Reassess bi-annually, or more frequently.
- Remove or deny access to unnecessary and potentially vulnerable software to prevent abuse by adversaries. (M1042: Disable or Remove Feature or Program)
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- Safeguard 2.3: Address Unauthorized Software: Ensure that unauthorized software is either removed from use on enterprise assets or receives a documented exception. Review monthly, or more frequently.
- Safeguard 2.5: Allowlist Authorized Software: Use technical controls, such as application allowlisting, to ensure that only authorized software can execute or be accessed. Reassess bi-annually, or more frequently.
- Safeguard 2.7: Allowlist Authorized Scripts: Use technical controls, such as digital signatures and version control, to ensure that only authorized scripts, such as specific .ps1, .py, etc., files, are allowed to execute. Block unauthorized scripts from executing. Reassess bi-annually, or more frequently.
- Safeguard 4.1: Establish and Maintain a Secure Configuration Process: Establish and maintain a secure configuration process for enterprise assets (end-user devices, including portable and mobile, non-computing/IoT devices, and servers) and software (operating systems and applications). Review and update documentation annually, or when significant enterprise changes occur that could impact this Safeguard.
- Safeguard 4.8: Uninstall or Disable Unnecessary Services on Enterprise Assets and Software: Uninstall or disable unnecessary services on enterprise assets and software, such as an unused file sharing service, web application module, or service function.
- Safeguard 18.3: Remediate Penetration Test Findings: Remediate penetration test findings based on the enterprise’s policy for remediation scope and prioritization.
- Safeguard 18.5: Perform Periodic Internal Penetration Tests: Perform periodic internal penetration tests based on program requirements, no less than annually. The testing may be clear box or opaque box.
Cisco:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-webui-privesc-j22SaA4z
CVE:
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-20198
October 27th – UPDATED REFERENCES:
CISA:
https://www.cisa.gov/guidance-addressing-cisco-ios-xe-web-ui-vulnerabilities
Multi-State Information Sharing and Analysis Center (MS-ISAC)
Elections Infrastructure Information Sharing and Analysis Center (EI-ISAC)
31 Tech Valley Drive
East Greenbush, NY 12061
24×7 Security Operations Center
SOC@cisecurity.org – 1-866-787-4722
TLP:CLEAR
www.cisa.gov/tlp
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