{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/black-basta-ransomware/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[],"_cs_exploited":false,"_cs_products":["ESXi","Splunk Enterprise","Splunk Enterprise Security","Splunk Cloud"],"_cs_severities":["medium"],"_cs_tags":["esxi","vmware","syslog","anomaly","T1601.001","T1685","ESXi Post Compromise","Black Basta Ransomware","Infrastructure","endpoint"],"_cs_type":"advisory","_cs_vendors":["VMWare","Splunk"],"content_html":"\u003cp\u003eThis detection focuses on identifying failed file download attempts on VMware ESXi hosts by analyzing system logs for specific error messages. The errors may stem from unauthorized or malicious attempts to install or update components, such as VIBs (vSphere Installation Bundles) or scripts, potentially leading to system compromise or disruption. This is important for defenders because successful exploitation could result in the installation of malicious software, unauthorized modifications to the ESXi host, or even complete system takeover. The detection leverages ESXi syslog data and is designed to be implemented within a Splunk environment using the appropriate technology add-on for VMware ESXi Logs.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eThe attacker gains initial access to a system with the ability to interact with the ESXi host (e.g., through compromised credentials or a vulnerability).\u003c/li\u003e\n\u003cli\u003eThe attacker attempts to download a malicious VIB or script onto the ESXi host.\u003c/li\u003e\n\u003cli\u003eThe ESXi host attempts to download the file from a remote location.\u003c/li\u003e\n\u003cli\u003eThe download fails due to network issues, file integrity checks, or access restrictions.\u003c/li\u003e\n\u003cli\u003eThe ESXi host logs an error message indicating the failed download attempt. Messages include \u0026ldquo;\u003cem\u003eDownload failed\u003c/em\u003e\u0026rdquo;, \u0026ldquo;\u003cem\u003eFailed to download file\u003c/em\u003e\u0026rdquo;, \u0026ldquo;\u003cem\u003eFile download error\u003c/em\u003e\u0026rdquo;, \u0026ldquo;\u003cem\u003eCould not download\u003c/em\u003e\u0026rdquo;.\u003c/li\u003e\n\u003cli\u003eThe system logs are forwarded to a SIEM such as Splunk for analysis.\u003c/li\u003e\n\u003cli\u003eA detection rule identifies the error message in the logs and triggers an alert.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation following a failed download attempt could lead to the installation of malicious software, unauthorized modification of the ESXi host configuration, or denial of service. While the detection identifies \u003cem\u003efailed\u003c/em\u003e download attempts, repeated failures or unusual patterns of failed downloads can indicate a persistent and potentially sophisticated attack. The impact could range from system instability to full compromise, depending on the attacker\u0026rsquo;s objectives and the vulnerabilities exploited.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eConfigure ESXi hosts to forward syslog output to your Splunk deployment to collect the necessary log data.\u003c/li\u003e\n\u003cli\u003eInstall and configure the Splunk Technology Add-on for VMware ESXi Logs to ensure proper field extraction and CIM compatibility.\u003c/li\u003e\n\u003cli\u003eDeploy the provided Splunk search query to identify ESXi download errors in your environment.\u003c/li\u003e\n\u003cli\u003eTune the detection logic and filter list (\u003ccode\u003eesxi_download_errors_filter\u003c/code\u003e) to reduce false positives based on your environment\u0026rsquo;s specific characteristics.\u003c/li\u003e\n\u003cli\u003eInvestigate alerts generated by the detection to determine the root cause of the failed download attempts.\u003c/li\u003e\n\u003cli\u003eUse the drilldown searches to view detection results and risk events associated with the identified hosts.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2024-01-03T12:00:00Z","date_published":"2024-01-03T12:00:00Z","id":"/briefs/2024-01-03-esxi-download-errors/","summary":"Detection of failed file download attempts on ESXi hosts, potentially indicating unauthorized or malicious activity such as installing or updating components, including VIBs or scripts.","title":"ESXi Download Error Detection","url":"https://feed.craftedsignal.io/briefs/2024-01-03-esxi-download-errors/"}],"language":"en","title":"CraftedSignal Threat Feed — Black Basta Ransomware","version":"https://jsonfeed.org/version/1.1"}