Name:ESXi Malicious VIB Forced Install id:5d4d2cd2-7b65-4474-97cf-e9b203bcd770 version:1 date:2025-05-09 author:Raven Tait, Splunk status:production type:TTP Description:Detects potentially malicious installation of VMware Installation Bundles (VIBs) using the --force flag. The --force option bypasses signature and compatibility checks, allowing unsigned, community-supported, or incompatible VIBs to be installed on an ESXi host. This behavior is uncommon in normal administrative operations and is often observed in post-compromise scenarios where adversaries attempt to install backdoored or unauthorized kernel modules, drivers, or monitoring tools to establish persistence or gain deeper control of the hypervisor. Data_source:
-VMWare ESXi Syslog
search:`esxi_syslog` Message="* image profile with validation disabled. *" OR Message="* image profile bypassing signing and acceptance level verification. *" OR Message="* vib without valid signature, *" | rex field=_raw "Z (?<dest>[\w\.]+)\s" | stats min(_time) as firstTime max(_time) as lastTime count by dest Message | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `esxi_malicious_vib_forced_install_filter`
how_to_implement:This is based on syslog data generated by VMware ESXi hosts. To implement this search, you must configure your ESXi systems to forward syslog output to your Splunk deployment. These logs must be ingested with the appropriate Splunk Technology Add-on for VMware ESXi Logs, which provides field extractions and CIM compatibility. known_false_positives:Some third party vendor VIBs or patches may require the force option. References: -https://detect.fyi/detecting-and-responding-to-esxi-compromise-with-splunk-f33998ce7823 drilldown_searches: name:'View the detection results for - "$dest$"' search:'%original_detection_search% | search dest = "$dest$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$dest$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'ESXi Post Compromise' - 'Black Basta Ransomware' asset_type:Infrastructure mitre_attack_id: - 'T1505.006' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' security_domain:endpoint
