cbcvebase.
CVE-2019-1295
published 2019-09-11

CVE-2019-1295: A remote code execution vulnerability exists in Microsoft SharePoint where APIs aren't properly protected from unsafe data input, aka 'Microsoft SharePoint…

PriorityP356high8.8CVSS 3.1
AVNACLPRLUINSUCHIHAH
EPSS
8.33%
94.3th percentile
A remote code execution vulnerability exists in Microsoft SharePoint where APIs aren't properly protected from unsafe data input, aka 'Microsoft SharePoint Remote Code Execution Vulnerability'. This CVE ID is unique from CVE-2019-1257, CVE-2019-1296.

Affected

11 ranges
VendorProductVersion rangeFixed in
microsoftmicrosoft_sharepoint_enterprise_server
microsoftmicrosoft_sharepoint_foundation
microsoftmicrosoft_sharepoint_server
microsoftsharepoint_enterprise_server
microsoftsharepoint_foundation
microsoftsharepoint_foundation
microsoftsharepoint_server
msrcmicrosoft_sharepoint_enterprise_server_2016
msrcmicrosoft_sharepoint_foundation_2010_service_pack_2
msrcmicrosoft_sharepoint_foundation_2013_service_pack_1
msrcmicrosoft_sharepoint_server_2019

Detection & IOCsextracted from sources · hover to see the quote

  • Exploit requires a BDC model parameter of type Microsoft.BusinessData.Runtime.DynamicType, which triggers deserialization of an arbitrary XmlSerializer stream; monitor SharePoint BDC model uploads for this type string.
  • Successful exploitation spawns child processes cmd.exe and win32calc.exe (or attacker payload) under the SharePoint application pool worker process (w3wp.exe); alert on w3wp.exe spawning cmd.exe or unexpected child processes.
  • Set a breakpoint or monitor for calls to System.Web.UI.ObjectStateFormatter.Deserialize within w3wp.exe as an indicator of exploitation in progress.
  • The vulnerability is triggered via a susceptible API endpoint on SharePoint accepting specially-formatted (deserialization payload) input; monitor SharePoint API calls with anomalous or oversized serialized data bodies.
  • BDC model upload via SharePoint Central Administration or PowerShell is a prerequisite attack step; audit and alert on new BDC model uploads, especially those containing DynamicType parameter definitions.
  • ·The exploit was specifically tested and confirmed on Microsoft SharePoint Server 2016 with KB4464594 installed on 64-bit Windows Server 2016 update 14393.3025; other versions are also affected but this is the confirmed test environment.
  • ·Exploitation requires an administrator account to first upload a malicious BDC model; the attacker then invokes the method with a deserialization payload. This is a two-stage attack requiring admin-level initial access for the setup step.
  • ·The Preview Pane is explicitly NOT an attack vector for this vulnerability.

CVSS provenance

nvdv3.18.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
nvdv2.06.5MEDIUMAV:N/AC:L/Au:S/C:P/I:P/A:P
vendor_msrc8.8CRITICAL
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