Sigma Rules
354 rules found for "initial-access"
Shai-Hulud Malicious Bun Execution - Linux
Detects the execution of `bun_environment.js` via the Bun runtime, a behavior associated with the Shai-Hulud "Second Coming" NPM supply chain attack. The malware uses a `setup_bun.js` script to install the Bun runtime if not present, and then executes the malicious `bun_environment.js` payload.
Shai-Hulud 2.0 Malicious NPM Package Installation - Linux
Detects the command-line installation of specific malicious npm packages and versions associated with the Shai-Hulud 2.0 supply chain attack.
Shai-Hulud Malicious Bun Execution
Detects the execution of `bun_environment.js` via the Bun runtime, a behavior associated with the Shai-Hulud "Second Coming" NPM supply chain attack. The malware uses a `setup_bun.js` script to install the Bun runtime if not present, and then executes the malicious `bun_environment.js` payload.
Shai-Hulud 2.0 Malicious NPM Package Installation
Detects the command-line installation of specific malicious npm packages and versions associated with the Shai-Hulud 2.0 supply chain attack.
Axios NPM Compromise File Creation Indicators - Linux
Detects file creation events linked to the Axios NPM supply chain compromise. Axios is a popular JavaScript HTTP client. On March 30, 2026, malicious versions (1.14.1, 0.30.4) were published to npm, injecting a dependency (plain-crypto-js@4.2.1) that executed a postinstall script as a cross-platform RAT dropper.
Axios NPM Compromise File Creation Indicators - MacOS
Detects file creation events linked to the Axios NPM supply chain compromise on macOS devices. Axios is a popular JavaScript HTTP client. On March 30, 2026, malicious versions (1.14.1, 0.30.4) were published to npm, injecting a dependency (plain-crypto-js@4.2.1) that executed a postinstall script as a cross-platform RAT dropper.
Axios NPM Compromise File Creation Indicators - Windows
Detects file creation events linked to the Axios NPM supply chain compromise. Axios is a popular JavaScript HTTP client. On March 30, 2026, malicious versions (1.14.1, 0.30.4) were published to npm, injecting a dependency (plain-crypto-js@4.2.1) that executed a postinstall script as a cross-platform RAT dropper. The dropper contacted a C2 server, delivered platform-specific payloads, deleted itself, and replaced package.json to evade detection. The attack used cscript.exe (VBScript), curl.exe (C2), and PowerShell masquerading as Windows Terminal.
Axios NPM Compromise Indicators - Linux
Detects the Linux-specific execution chain of the plain-crypto-js malicious npm dependency by Axios NPM package, including payload download via curl and detached execution using nohup and python3. On March 30, 2026, malicious versions (1.14.1, 0.30.4) were published to npm, injecting a dependency (plain-crypto-js@4.2.1) that executed a postinstall script as a cross-platform RAT dropper. The dropper contacted a C2 server, delivered platform-specific payloads, deleted itself, and replaced package.json to evade detection.
Axios NPM Compromise Indicators - macOS
Detects the macOS-specific execution chain of the plain-crypto-js malicious npm dependency in Axios NPM Package, including AppleScript execution via osascript, payload download, permission modification, execution, and cleanup.
Axios NPM Compromise Indicators - Windows
Detects the specific Windows execution chain and process tree associated with the Axios NPM supply chain compromise. On March 30, 2026, malicious versions (1.14.1, 0.30.4) were published to npm, injecting a dependency (plain-crypto-js@4.2.1) that executed a postinstall script as a cross-platform RAT dropper. The dropper contacted a C2 server, delivered platform-specific payloads, deleted itself, and replaced package.json to evade detection. The attack used cscript.exe (VBScript), curl.exe (C2), and PowerShell masquerading as Windows Terminal.
TeamPCP LiteLLM Supply Chain Attack Persistence Indicators
Detects the creation of specific persistence files as observed in the LiteLLM PyPI supply chain attack. In March 2026, a supply chain attack was discovered involving the popular open-source LLM framework LiteLLM by Threat Actor TeamPCP. The malicious package harvests every credential on the system, encrypts and exfiltrates them, and installs a persistent C2 backdoor.
LiteLLM / TeamPCP Supply Chain Attack Indicators
Detects process executions related to the backdoored versions of LiteLLM (v1.82.7 or v1.82.8). In March 2026, a supply chain attack was discovered involving the popular open-source LLM framework LiteLLM by Threat Actor TeamPCP. The malicious package harvests every credential on the system, encrypts and exfiltrates them, and installs a persistent C2 backdoor.
Low Reputation Effective Top-Level Domain (eTLD)
Detects DNS queries to domains within known low reputation eTLDs. This rule uses AlphaSOC's threat intelligence data and is updated on a monthly basis.
.Class Extension URI Ending Request
Detects requests to URI ending with the ".class" extension in proxy logs. This could rules can be used to hunt for potential downloads of Java classes as seen for example in Log4shell exploitation attacks against Log4j.
WebDAV Temporary Local File Creation
Detects the creation of WebDAV temporary files with potentially suspicious extensions
Microsoft Word Add-In Loaded
Detects Microsoft Word loading an Add-In (.wll) file which can be used by threat actors for initial access or persistence.
HTML File Opened From Download Folder
Detects web browser process opening an HTML file from a user's Downloads folder. This behavior is could be associated with phishing attacks where threat actors send HTML attachments to users. When a user opens such an attachment, it can lead to the execution of malicious scripts or the download of malware. During investigation, analyze the HTML file for embedded scripts or links, check for any subsequent downloads or process executions, and investigate the source of the email or message containing the attachment.
Default Credentials Usage
Before deploying any new asset, change all default passwords to have values consistent with administrative level accounts. Sigma detects default credentials usage. Sigma for Qualys vulnerability scanner. Scan type - Vulnerability Management.