cbcvebase.
CVE-2023-24955
published 2023-05-09

CVE-2023-24955: Microsoft SharePoint Server Remote Code Execution Vulnerability

PriorityP188high7.2CVSS 3.1
AVNACLPRHUINSUCHIHAH
KEVITWEXPLOITRansomware
CISA Known Exploited Vulnerabilitydue 2024-04-16
Exploited in the wild
EPSS
85.39%
99.7th percentile
Microsoft SharePoint Server Remote Code Execution Vulnerability

Affected

8 ranges
VendorProductVersion rangeFixed in
microsoftmicrosoft_sharepoint_enterprise_server_2016>= 16.0.0 < 16.0.5395.100016.0.5395.1000
microsoftmicrosoft_sharepoint_server_2019>= 16.0.0 < 16.0.10398.2000016.0.10398.20000
microsoftmicrosoft_sharepoint_server_subscription_edition>= 16.0.0 < 16.0.16130.2042016.0.16130.20420
microsoftsharepoint_enterprise_server
microsoftsharepoint_server
msrcmicrosoft_sharepoint_enterprise_server_2016
msrcmicrosoft_sharepoint_server_2019
msrcmicrosoft_sharepoint_server_subscription_edition

Detection & IOCsextracted from sources · hover to see the quote

path/BusinessDataMetadataCatalog/BDCMetadata.bdcm
  • Detect JWT tokens with signing algorithm set to 'none' in SharePoint OAuth authentication requests — this is the core auth bypass mechanism for CVE-2023-29357 (chained with CVE-2023-24955 for RCE). SharePoint skips signature validation when the JWT algorithm field is 'none' due to a logic flaw in ReadTokenCore().
  • Monitor SharePoint webroot for unexpected creation or modification of the file 'BDCMetadata.bdcm' under the BusinessDataMetadataCatalog directory, which is the payload staging location used in CVE-2023-24955 exploitation.
  • A YARA rule is available to help network defenders analyze logs for signs of potential exploitation on their SharePoint servers using the CVE-2023-29357 PoC exploit (which is the auth bypass prerequisite for CVE-2023-24955 RCE).
  • The exploit chain involves an unauthenticated attacker first spoofing a JWT authentication token to gain admin privileges (CVE-2023-29357), then using the SharePoint API to inject and execute code via CVE-2023-24955. Monitor SharePoint API calls made with newly elevated or anomalous admin tokens.
  • ·CVE-2023-24955 requires the attacker to already have authenticated Site Owner privileges on SharePoint Server. In practice, exploitation requires chaining with CVE-2023-29357 (auth bypass) to achieve unauthenticated RCE. Standalone exploitation of CVE-2023-24955 requires a privileged account.
  • ·The initially released public PoC (September 26, 2023) did not include full RCE capability for CVE-2023-24955 — it only demonstrated the CVE-2023-29357 auth bypass. However, subsequent PoCs including a Metasploit module implement the full chain. Defenders should not assume partial PoC availability limits attacker capability.
  • ·CISA confirmed active exploitation of CVE-2023-24955 but stated there is no evidence it has been used in ransomware attacks at the time of reporting.

CVSS provenance

nvdv3.17.2HIGHCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
vulncheck7.2HIGH
cisa7.2HIGH
vendor_msrc7.2HIGH
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