cbcvebase.
CVE-2019-1296
published 2019-09-11

CVE-2019-1296: 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%
94.4th 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-2019-1295.

Affected

10 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_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 under the SharePoint application pool worker process (w3wp.exe); alert on w3wp.exe spawning cmd.exe or calc-family processes.
  • Set a breakpoint / monitor for calls to System.Web.UI.ObjectStateFormatter.Deserialize within w3wp.exe on SharePoint servers as an indicator of exploitation in progress.
  • Exploitation path runs through w3wp.exe (SharePoint application pool); monitor this process for anomalous child process creation or unusual outbound network connections.
  • The vulnerability is triggered via a susceptible API endpoint receiving specially-formatted (deserialization payload) input; inspect HTTP requests to SharePoint APIs for malformed/serialized XML payloads.
  • 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 detailed exploit walkthrough in the source documents describes CVE-2019-1257 (ZDI-19-812), which is a related but distinct SharePoint deserialization RCE; CVE-2019-1296 shares the same deserialization root cause (unsafe API input / untrusted data deserialization) and the same patch cycle, so detection hints derived from the exploit mechanics are applicable to both.
  • ·The vulnerability affects Microsoft SharePoint where APIs are not properly protected from unsafe data input; the security update corrects how SharePoint handles deserialization of untrusted data, so patching is the primary mitigation.
  • ·Exploitation is rated 'Exploitation More Likely' for both latest and older software releases by Microsoft, indicating a higher probability of weaponization even though no public exploit or active exploitation was confirmed at time of disclosure.

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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