Microsoft Exchange Server 2016 CU23/2019 CU12/2019 CU13 excessive authentication

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
8.9$0-$5k0.00

Summaryinfo

A vulnerability was found in Microsoft Exchange Server 2016 CU23/2019 CU12/2019 CU13. It has been declared as very critical. This affects an unknown function. The manipulation results in an unknown weakness. This vulnerability was named CVE-2023-21709. The attack may be performed from remote. There is no available exploit. It is advisable to implement a patch to correct this issue.

Detailsinfo

A vulnerability was found in Microsoft Exchange Server 2016 CU23/2019 CU12/2019 CU13 (Groupware Software). It has been classified as very critical. CWE is classifying the issue as CWE-307. The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame, making it more susceptible to brute force attacks. This is going to have an impact on confidentiality, integrity, and availability.

The weakness was presented 08/08/2023 as confirmed security guidance (Website). The advisory is shared for download at portal.msrc.microsoft.com. This vulnerability is traded as CVE-2023-21709. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/01/2023). The MITRE ATT&CK project declares the attack technique as T1110.001.

Applying a patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.8
VulDB Meta Temp Score: 8.9

VulDB Base Score: 9.8
VulDB Temp Score: 8.5
VulDB Vector: 🔍
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 9.8
Vendor Vector (Microsoft): 🔍

CNA Base Score: 9.8
CNA Vector (Microsoft): 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Excessive authentication
CWE: CWE-307 / CWE-799 / CWE-400
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Unproven

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Timelineinfo

12/13/2022 🔍
08/08/2023 +238 days 🔍
08/08/2023 +0 days 🔍
08/08/2023 +0 days 🔍
09/01/2023 +24 days 🔍

Sourcesinfo

Vendor: microsoft.com

Advisory: portal.msrc.microsoft.com
Status: Confirmed

CVE: CVE-2023-21709 (🔍)
GCVE (CVE): GCVE-0-2023-21709
GCVE (VulDB): GCVE-100-236508

Entryinfo

Created: 08/08/2023 20:26
Updated: 09/01/2023 14:53
Changes: 08/08/2023 20:26 (21), 08/08/2023 20:27 (13), 08/08/2023 20:30 (19), 09/01/2023 14:49 (1), 09/01/2023 14:53 (11)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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