Splunk Security
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This analytic detects suspicious use of 'mshta.exe' or 'rundll32.exe' invoking 'mshtml.dll' or the 'RunHTMLApplication' export without including a direct HTTP/HTTPS URL in the command line. This pattern could be associated with obfuscated script execution used by threat actors during initial access or payload staging. The absence of a visible URL may indicate attempts to evade static detections by embedding the URL via string concatenation, encoding (e.g., hex), or indirect script loaders like 'GetObject()'.
The analytic detects the use of msiexec.exe with an HTTP or HTTPS URL in the command line, indicating a remote file download attempt. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution logs that include command-line details. This activity is significant as it may indicate an attempt to download and execute potentially malicious software from a remote server. If confirmed malicious, this could lead to unauthorized code execution, system compromise, or further malware deployment within the network.
This analytic detects oversized Cisco Smart Install (SMI) protocol messages by inspecting traffic to TCP port 4786 within the Network_Traffic data model. Abnormally large SMI payloads have been associated with exploitation and protocol abuse (e.g., CVE-2018-0171; activity reported by the "Static Tundra" threat actor). Monitoring message sizes over time can help identify possible attempts at remote code execution, denial of service, or reconnaissance against Cisco devices exposing Smart Install.
This detection identifies execution of the file synchronization utility "rclone" with network activity, as captured by Cisco Network Visibility Module flow data. It specifically looks for `rclone.exe` or `rclone` commands with arguments indicative of data transfer to cloud storage providers (e.g., `copy`, `remote:`, `mega:`, `ftp:`) and suspicious flags (`--transfers`, `--ignore-existing`, `--auto-confirm`). Rclone is a legitimate tool but is frequently abused by threat actors for data exfiltration or cloud abuse.
Detection rule generated by AI system
The analytic detects `wmic.exe` loading a remote XSL script via a URL. This detection leverages Endpoint Detection and Response (EDR) data, focusing on command-line executions that include HTTP/HTTPS URLs and the /FORMAT switch. This activity is significant as it indicates a potential application control bypass, allowing adversaries to execute JScript or VBScript within an XSL file. If confirmed malicious, this technique can enable attackers to execute arbitrary code, escalate privileges, or maintain persistence using a trusted Windows tool, posing a severe threat to the environment.
This analytic detects network traffic to TCP port 4786, which is used by the Cisco Smart Install protocol. Smart Install is a plug-and-play configuration and image-management feature that helps customers to deploy Cisco switches. This protocol has been exploited via CVE-2018-0171, a vulnerability that allows unauthenticated remote attackers to execute arbitrary code or cause denial of service conditions. Recently, Cisco Talos reported that a Russian state-sponsored threat actor called "Static Tundra" has been actively exploiting this vulnerability to compromise unpatched and end-of-life network devices. Monitoring for traffic to this port can help identify potential exploitation attempts or unauthorized Smart Install activity.
The analytic detects the Windows InstallUtil.exe binary making a remote network connection. This activity is significant because InstallUtil.exe can be exploited to download and execute malicious code, bypassing application control mechanisms. If confirmed malicious, an attacker could achieve code execution, potentially leading to further system compromise, data exfiltration, or lateral movement within the network. Analysts should review the parent process, network connections, and any associated file modifications to determine the legitimacy of this activity.
This analytic detects the execution of PowerShell commands to install unsigned AppX packages using Add-AppxPackage or Add-AppPackage cmdlets with the -AllowUnsigned flag. This activity is significant as adversaries may use unsigned AppX packages to install malicious applications, bypass security controls, or establish persistence. If confirmed malicious, this could allow attackers to install unauthorized applications that may contain malware, backdoors, or other malicious components.
This analytic detects suspicious use of `rundll32.exe` in combination with `mshtml.dll` and the export `RunHTMLApplication`. This behavior is often observed in malware to execute JavaScript or VBScript in memory, enabling payload staging or bypassing script execution policies and bypassing the usage of the "mshta.exe" binary. The detection leverages Cisco Network Visibility Module telemetry which offers network flow activity along with process information such as command-line arguments. If confirmed malicious, this activity may indicate initial access or payload download.
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