CVE-2023-41763: Skype for Business Elevation of Privilege Vulnerability

Overview

Severity
Medium (CVSS 5.3)
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:P/RL:O/RC:C
Category
Elevation of Privilege
Exploit Status
Actively Exploited
Exploitation Likelihood
Detected
Publicly Disclosed
Yes
Patch Tuesday
2023-Oct
Released
2023-10-10
EPSS Score
19.17% (percentile: 95.4%)
CISA KEV
Listed — due 2023-10-31

FAQ

How could an attacker exploit this vulnerability? An attacker could make a specially crafted network call to the target Skype for Business server, which could cause the parsing of an http request made to an arbitrary address. This could disclose IP addresses or port numbers or both to the attacker. According to the CVSS metrics, successful exploitation of this vulnerability could lead to some loss of confidentiality (C:L) but have no effect on integrity (I:N) or on availability (A:N). What does that mean for this vulnerability? An attacker who successfully exploited the vulnerability could view some sensitive information (Confidentiality) but not all resources within the impacted component may be divulged to the attacker. The attacker cannot make changes to disclosed information (Integrity) or limit access to the resource (Availability). If the successful attacker only could view some sensitive information, how is this an elevation of privilege vulnerability? In some cases, the exposed sensitive information could provide access to internal networks.

Detection & Weaponization (1 sources)

Maturity: Exploit

  • Nuclei templates: Skype for Business 2019 (SfB) - Blind Server-side Request Forgery

Affected Products (2)

Microsoft Office

  • Skype for Business Server 2015 CU13
  • Skype for Business Server 2019 CU7

Security Updates (2)

Acknowledgments

Anonymous, Dr. Florian Hauser (@frycos) with Code White GmbH, Anonymous, Anonymous

Revision History

  • 2023-10-10: Information published.