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CVE

CVE-2023-20198

Cisco IOS XE Web UI Privilege Escalation Vulnerability

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.

CRITICAL · CVSS 10 ⚠ CISA KEV EPSS 0.94013
Act now
  • Listed on CISA KEV (known exploited in the wild)
  • SSVC exploitation status: active
  • EPSS ≥ 0.50 - high probability of exploitation in the next 30 days
  • EPSS percentile: top 0% of all CVEs by exploitation likelihood
  • Public exploit or PoC is available
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules10 YARA rules0
⬢

Required Remediation

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.

◆

Threat Actors Linked

2
actorSalt Typhoon
actorTAG-100
⬡

Weakness Classification

CWE-420Unprotected Alternate Channel
▤

Affected Products & Versions

6
rockwellautomation allen-bradley stratix 5200 firmware< 17.12.02
rockwellautomation allen-bradley stratix 5800 firmware< 17.12.02
cisco ios xe>= 16.12 and < 16.12.10a
cisco ios xe>= 17.3 and < 17.3.8a
cisco ios xe>= 17.6 and < 17.6.6a
cisco ios xe>= 17.9 and < 17.9.4a
⚠

Public Exploits & PoCs

2
nucleiCisco IOS XE - Impant Detectioncritical
nucleiCisco IOS XE Web UI - Command Injectioncritical
◈

Detection Rules (IDS/IPS)

15
et-openET EXPLOIT Cisco IOS XE Web Server Implant Check (CVE-2023-20198) (Inbound) M1trojan-activity
et-openET EXPLOIT Cisco IOS XE Web Server Implant Check (CVE-2023-20198) (Outbound) M1trojan-activity
et-openET INFO Cisco IOS XE Web Server Auth From Suspicious Username (cisco_support) (CVE-2023-20198) (Inbound)misc-activity
et-openET HUNTING Suspicious Cisco Privilege Level 15 in HTTP Header (Inbound)misc-activity
et-openET HUNTING Suspicious Cisco Privilege Level 15 in HTTP Header (Outbound)misc-activity
et-openET HUNTING Cisco IOS XE Web Server Auth From Suspicious Username (cisco_tac_admin) (CVE-2023-20198) (Inbound)misc-activity
Open rulesets (ET Open, Snort Community, abuse.ch) link to source. Commercial rulesets are reference-only.
◈

Sigma Hunt Rules

10
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
relatedcriticalAntivirus Password Dumper Detection
relatedcriticalHacktool Execution - Imphash
relatedcriticalHackTool - Rubeus Execution
relatedcriticalPotential Credential Dumping Via LSASS Process Clone
relatedcriticalWCE wceaux.dll Access
relatedcriticalHackTool - Dumpert Process Dumper Default File
▣

Scoring & Timeline

10
CRITICAL · CVSS v3.1 · psirt@cisco.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD16 Oct 2023 · 04:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
yes
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

4
cisaKEV-CVE-2023-20198
cisco-csafcisco-sa-iosxe-webui-privesc-j22SaA4z
splunk-security-content07c36cda-6567-43c3-bc1a-89dff61e2cd9
cisa-csafcisa-csaf-csaf_files-OT-white-2023-icsa-23-297-01
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-webui-privesc-j22SaA4zMitigationVendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-20198US Government Resource
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