Microsoft Exchange Server ChainedSerializationBinder Deny List Typo RCE
Description
This vulnerability allows remote attackers to execute arbitrary code on Exchange Server 2019 CU10 prior to Security Update 3, Exchange Server 2019 CU11 prior to Security Update 2, Exchange Server 2016 CU21 prior to Security Update 3, and Exchange Server 2016 CU22 prior to Security Update 2. Note that authentication is required to exploit this vulnerability. The specific flaw exists due to the fact that the deny list for the ChainedSerializationBinder had a typo whereby an entry was typo'd as System.Security.ClaimsPrincipal instead of the proper value of System.Security.Claims.ClaimsPrincipal. By leveraging this vulnerability, attacks can bypass the ChainedSerializationBinder's deserialization deny list and execute code as NT AUTHORITY\SYSTEM. Tested against Exchange Server 2019 CU11 SU0 on Windows Server 2019, and Exchange Server 2016 CU22 SU0 on Windows Server 2016.
Author(s)
- pwnforsp
- zcgonvh
- Microsoft Threat Intelligence Center
- Microsoft Security Response Center
- peterjson
- testanull
- Grant Willcox
Platform
Windows
Architectures
cmd, x86, x64
Development
Module Options
To display the available options, load the module within the Metasploit console and run the commands 'show options' or 'show advanced':
msf > use exploit/windows/http/exchange_chainedserializationbinder_denylist_typo_rce
msf exploit(exchange_chainedserializationbinder_denylist_typo_rce) > show targets
...targets...
msf exploit(exchange_chainedserializationbinder_denylist_typo_rce) > set TARGET < target-id >
msf exploit(exchange_chainedserializationbinder_denylist_typo_rce) > show options
...show and set options...
msf exploit(exchange_chainedserializationbinder_denylist_typo_rce) > exploit
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