Background exploitation KEV catalog No authentication

CVE-2023-20198

Cisco IOS XE Web UI Privilege Escalation Vulnerability

CheckOps priority index

9.4/10 Patch within 24 h

Severity10.0

Probability10.0

Exploitation4/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 99.6% higher than 99.9% of CVEs

CVSS 3.1 10.0 AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:

Exploited for 1,114 days 16 Oct 2023

CISA due date 20 Oct 2023 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 4 / 5

KEV catalog (CISA)16 Oct 2023
Exploited in EUVD (ENISA)16 Oct 2023
Used by ransomwareno
EPSS above 10 %99.6%
No account, over the networkyes

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: 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.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Description ENISA EUVD

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.

Affected products

Cisco IOS XE SoftwareIOS XE Web UI

Affected versions

16.4.2
17.6.1
17.11.1
16.9.3a
16.5.1a
17.9.1x1
16.10.1
16.9.8
16.12.7
17.2.1v
16.5.3
16.7.1a

Weaknesses (CWE)

CWE-420

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

16 Oct 2023
Published
16 Oct 2023
Exploitation reported (ENISA)
16 Oct 2023
Added to the KEV catalog
20 Oct 2023
CISA remediation due date
17 Oct 2026
EPSS peak: 99.6%

References

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