CyberSecBulletin
CVE-2023-20198Exploited in the wildNVD status: Analyzed

Cisco IOS XE Web UI Privilege Escalation

Published Updated By the CyberSecBulletin desk

CVE-2023-20198 is a critical-severity unprotected alternate channel vulnerability in Cisco IOS XE Software from Cisco, with a CVSS 3.1 base score of 10.0 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Cisco IOS XE Software versions: 16.1.1; 16.1.2; 16.1.3, and others listed below. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on October 16, 2023, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Allen-bradley Stratix 5200 Firmware to 17.12.02 or a later version.
  2. Update Allen-bradley Stratix 5800 Firmware to 17.12.02 or a later version.
  3. Update iOS Xe to 16.12.10a or 17.3.8a or 17.6.6a or 17.9.4a, whichever matches your release line, or a later version.
  4. CISA's required action: Verify that instances of Cisco IOS XE Web UI are in compliance with BOD 23-02 and apply mitigations per vendor instructions. For affected products (Cisco IOS XE Web UI exposed to the internet or to untrusted networks), follow vendor instructions to determine if a system may have been compromised and immediately report positive findings to CISA.
  5. Read the advisory on sec.cloudapps.cisco.com for workarounds and exact fixed builds.
  6. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
CiscoCisco IOS XE Software16.1.1; 16.1.2; 16.1.3; 16.2.1; 16.2.2; 16.3.1; 16.3.2; 16.3.3; and 32 more rangesNot stated
Rockwell AutomationAllen-bradley Stratix 5200 Firmwarebefore 17.12.0217.12.02
Rockwell AutomationAllen-bradley Stratix 5800 Firmwarebefore 17.12.0217.12.02
CiscoiOS Xe16.12 up to, but not including, 16.12.10a; 17.3 up to, but not including, 17.3.8a; 17.6 up to, but not including, 17.6.6a; 17.9 up to, but not including, 17.9.4a16.12.10a, 17.3.8a, 17.6.6a, 17.9.4a

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.110.0CriticalCNA (cisco.com)
CVSS 3.110.0CriticalNVD

Official description

Cisco is providing an update for the ongoing investigation into observed exploitation of the web UI feature in Cisco IOS XE Software. We are updating the list of fixed releases and adding the Software Checker. Our investigation has determined that the actors exploited two previously unknown issues. The attacker first exploited CVE-2023-20198 to gain initial access and issued a privilege 15 command to create a local user and password combination. This allowed the user to log in with normal user access. The attacker then exploited another component of the web UI feature, leveraging the new local user to elevate privilege to root and write the implant to the file system. Cisco has assigned CVE-2023-20273 to this issue. CVE-2023-20198 has been assigned a CVSS Score of 10.0. CVE-2023-20273 has been assigned a CVSS Score of 7.2. Both of these CVEs are being tracked by CSCwh87343.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Unprotected Alternate Channel

The product protects a primary channel, but it does not use the same level of protection for an alternate channel.

How developers prevent this class of flaw

  • Identify all alternate channels and use the same protection mechanisms that are used for the primary channels.

More Unprotected Alternate Channel vulnerabilities (CWE-420)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. Deadline for US federal agencies to remediate, set by CISA.
  4. CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
  5. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in Cisco IOS XE Software

All Cisco IOS XE Software vulnerabilities

Recent Unprotected Alternate Channel vulnerabilities

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