Microsoft Excel Security Feature Bypass

Microsoft Excel Security Feature Bypass Vulnerability

CheckOps priority index

6.2/10 Patch within 7 days

Severity7.8

Probability4.3

Exploitation3/5

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

EPSS · today 43.0% higher than 98.7% of CVEs

CVSS 3.1 7.8 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:

Exploited for 1,813 days 17 Nov 2021

CISA due date 01 Dec 2021 for US federal agencies

Exploitation probability EPSS · FIRST

EPSS probability (%)Percentile among all CVEs

Exploitation signals 3 / 5

KEV catalog (CISA)17 Nov 2021
Exploited in EUVD (ENISA)17 Nov 2021
Used by ransomwareno
EPSS above 10 %43.0%
No account, over the networkno

What to do

Fix

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

CISA guidance: Apply updates per vendor instructions.

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

Affected products

Microsoft Office 2019 for MacMicrosoft Excel 2013 Service Pack 1Microsoft Excel 2016Microsoft Office LTSC 2021Microsoft Office LTSC for Mac 2021Microsoft Office 2016Microsoft Office 2019Microsoft 365 Apps for EnterpriseMicrosoft Office 2013 Service Pack 1Office

Affected versions

16.0.0 <16.55.21111400
15.0.0.0 <15.0.5397.1001
16.0.0.0 <16.0.5239.1001
16.0.1 <https://aka.ms/OfficeSecurityReleases
16.0.1 <16.55.21111400
16.0.0 <16.0.5239.1001
19.0.0 <https://aka.ms/OfficeSecurityReleases
15.0.0 <15.0.5397.1001

Weaknesses (CWE)

CWE-357

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

10 Nov 2021
Published
17 Nov 2021
Exploitation reported (ENISA)
17 Nov 2021
Added to the KEV catalog
01 Dec 2021
CISA remediation due date
26 Sept 2026
EPSS peak: 43.0%

References

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