cbcvebase.
CVE-2023-36035
published 2023-11-14

CVE-2023-36035: Microsoft Exchange Server Spoofing Vulnerability Microsoft Exchange Server Spoofing Vulnerability

high8CVSS 3.1
AVAACLPRLUINSUCHIHAH
EPSS
86.59%
99.7th percentile
Microsoft Exchange Server Spoofing Vulnerability Microsoft Exchange Server Spoofing Vulnerability

Affected

6 ranges
VendorProductVersion rangeFixed in
microsoftmicrosoft_exchange_server_2016_cumulative_update_23>= 15.01.0 < 15.01.2507.03515.01.2507.035
microsoftmicrosoft_exchange_server_2019_cumulative_update_12>= 15.02.0 < 15.02.1118.04015.02.1118.040
microsoftmicrosoft_exchange_server_2019_cumulative_update_13>= 15.02.0 < 15.02.1258.02815.02.1258.028
msrcmicrosoft_exchange_server_2016_cumulative_update_23
msrcmicrosoft_exchange_server_2019_cumulative_update_12
msrcmicrosoft_exchange_server_2019_cumulative_update_13

Detection & IOCsextracted from sources · hover to see the quote

commandPowerShell Remoting session to Exchange Server (authenticated, LAN access)
path\\?\UNC\<attacker>\<share>
otherMobileMailboxPolicy deserialization with ApprovedApplicationCollection member (ConvertViaNoArgumentConstructor gadget chain)
  • Monitor for PowerShell Remoting sessions to Exchange Server from authenticated LAN users, particularly those delivering serialized XML payloads containing MS tags with member definitions targeting MobileMailboxPolicy or ApprovedApplicationCollection types.
  • Detect UNC path bypass using the \\?\UNC\ prefix in Exchange PowerShell Remoting deserialization payloads; Uri.TryCreate returns null for this syntax, bypassing IsUNCPath checks while FileInfo still resolves the path, enabling NTLM relay.
  • Alert on outbound SMB/NTLM authentication attempts originating from the Exchange Server process to external or attacker-controlled hosts, which may indicate NTLM relay exploitation via CVE-2023-36035.
  • Require LAN-adjacent network segmentation and restrict authenticated Exchange PowerShell Remoting access; the attack vector is adjacent (AV:A) and requires valid Exchange user credentials (PR:L).
  • ·Exploitation requires an authenticated user with valid Exchange credentials and LAN adjacency; unauthenticated or remote-only attackers cannot exploit this vulnerability.
  • ·CVE-2023-36035 is a partial bypass for CVE-2023-36756; the path traversal/web shell upload is no longer possible, but NTLM relay via CAB extraction with the UNC path bypass remains the impact.

CVSS provenance

nvdv3.18.0HIGHCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cvelistv58.0HIGH
vendor_msrc8.0HIGH
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