Sigma Rules
1,585 rules found for "defense-evasion"
Access To Windows Outlook Mail Files By Uncommon Applications
Detects file access requests to Windows Outlook Mail by uncommon processes. Could indicate potential attempt of credential stealing. Requires heavy baselining before usage
Access To .Reg/.Hive Files By Uncommon Applications
Detects file access requests to files ending with either the ".hive"/".reg" extension, usually associated with Windows Registry backups.
File Creation Date Changed to Another Year
Detects when the file creation time is changed to a year before 2020. Attackers may change the file creation time of a backdoor to make it look like it was installed with the operating system. Note that many processes legitimately change the creation time of a file; it does not necessarily indicate malicious activity. In order to use this rule in production, it is recommended first baseline normal behavior in your environment and then tune the rule accordingly. Hunting Recommendation: Focus on files with creation times set to years significantly before the current date, especially those in user-writable directories. Correlate with process execution logs to identify the source of the modification and investigate any unsigned or suspicious binaries involved.
ADS Zone.Identifier Deleted
Detects the deletion of the "Zone.Identifier" ADS. Attackers can leverage this in order to bypass security restrictions that make use of the ADS such as Microsoft Office apps.
DMP/HDMP File Creation
Detects the creation of a file with the ".dmp"/".hdmp" extension. Often created by software during a crash. Memory dumps can sometimes contain sensitive information such as credentials. It's best to determine the source of the crash.
WDAC Policy File Creation In CodeIntegrity Folder
Attackers can craft a custom Windows Defender Application Control (WDAC) policy that blocks Endpoint Detection and Response (EDR) components while allowing their own malicious code. The policy is placed in the privileged Windows Code Integrity folder (C:\Windows\System32\CodeIntegrity\). Upon reboot, the policy prevents EDR drivers from loading, effectively bypassing security measures and may further enable undetected lateral movement within an Active Directory environment.
Non-DLL Extension File Renamed With DLL Extension
Detects rename operations of files with non-DLL extensions to files with a DLL extension. This is often performed by malware in order to avoid initial detections based on extensions.
Amsi.DLL Load By Uncommon Process
Detects loading of Amsi.dll by uncommon processes
BITS Client BitsProxy DLL Loaded By Uncommon Process
Detects an uncommon process loading the "BitsProxy.dll". This DLL is used when the BITS COM instance or API is used. This detection can be used to hunt for uncommon processes loading this DLL in your environment. Which may indicate potential suspicious activity occurring.
WerFaultSecure Loading DbgCore or DbgHelp - EDR-Freeze
Detects the loading of dbgcore.dll or dbghelp.dll by WerFaultSecure.exe, which has been observed in EDR-Freeze attacks to suspend processes and evade detection. However, this behavior has also been observed during normal software installations, so further investigation is required to confirm malicious activity. When threat hunting, look for this activity in conjunction with other suspicious processes starting, network connections, or file modifications that occur shortly after the DLL load. Pay special attention to timing - if other malicious activities occur during or immediately after this library loading, it may indicate EDR evasion attempts. Also correlate with any EDR/AV process suspension events or gaps in security monitoring during the timeframe.
Dllhost.EXE Initiated Network Connection To Non-Local IP Address
Detects Dllhost.EXE initiating a network connection to a non-local IP address. Aside from Microsoft own IP range that needs to be excluded. Network communication from Dllhost will depend entirely on the hosted DLL. An initial baseline is recommended before deployment.
HH.EXE Initiated HTTP Network Connection
Detects a network connection initiated by the "hh.exe" process to HTTP destination ports, which could indicate the execution/download of remotely hosted .chm files.
Msiexec.EXE Initiated Network Connection Over HTTP
Detects a network connection initiated by an "Msiexec.exe" process over port 80 or 443. Adversaries might abuse "msiexec.exe" to install and execute remotely hosted packages. Use this rule to hunt for potentially anomalous or suspicious communications.
Mail Forwarding/Redirecting Activity Via ExchangePowerShell Cmdlet
Detects email forwarding or redirecting activity via ExchangePowerShell Cmdlet
Inbox Rules Creation Or Update Activity Via ExchangePowerShell Cmdlet
Detects inbox rule creation or update via ExchangePowerShell cmdlet, a technique commonly observed in Business Email Compromise (BEC) attacks to hide emails. The usage of inbox rules can be a sign of a compromised mailbox, where an attacker is attempting to evade detections by suppressing or redirecting incoming emails. Analysts should review these rules in context, validate whether they reflect normal user behavior, and correlate with other indicators such as unusual login activity or recent mailbox rule modifications.
Windows Mail App Mailbox Access Via PowerShell Script
Detects PowerShell scripts that try to access the default Windows MailApp MailBox. This indicates manipulation of or access to the stored emails of a user. E.g. this could be used by an attacker to exfiltrate or delete the content of the emails.
New Windows Firewall Rule Added Via New-NetFirewallRule Cmdlet - ScriptBlock
Detects when a powershell script contains calls to the "New-NetFirewallRule" cmdlet in order to add a new firewall rule with an "Allow" action.
Use Of Remove-Item to Delete File - ScriptBlock
PowerShell Remove-Item with -Path to delete a file or a folder with "-Recurse"
Powershell Token Obfuscation - Powershell
Detects TOKEN OBFUSCATION technique from Invoke-Obfuscation in Powershell scripts. Use this rule as a threat-hunting baseline to find obfuscated scripts in your environment. Once tested and tuned, consider deploying a production detection rule based on this hunting rule.
Potential Shellcode Injection
Detects potential shellcode injection as seen used by tools such as Metasploit's migrate and Empire's psinject.
Set Files as System Files Using Attrib.EXE
Detects the execution of "attrib" with the "+s" flag to mark files as system files
Potential BOINC Software Execution (UC-Berkeley Signature)
Detects the use of software that is related to the University of California, Berkeley via metadata information. This indicates it may be related to BOINC software and can be used maliciously if unauthorized.
Potential File Override/Append Via SET Command
Detects the use of the "SET" internal command of Cmd.EXE with the /p flag followed directly by an "=" sign. Attackers used this technique along with an append redirection operator ">>" in order to update the content of a file indirectly. Ex: cmd /c >> example.txt set /p="test data". This will append "test data" to contents of "example.txt". The typical use case of the "set /p=" command is to prompt the user for input.
Headless Process Launched Via Conhost.EXE
Detects the launch of a child process via "conhost.exe" with the "--headless" flag. The "--headless" flag hides the windows from the user upon execution.
Dynamic .NET Compilation Via Csc.EXE - Hunting
Detects execution of "csc.exe" to compile .NET code. Attackers often leverage this to compile code on the fly and use it in other stages.
ClickOnce Deployment Execution - Dfsvc.EXE Child Process
Detects child processes of "dfsvc" which indicates a ClickOnce deployment execution.
Diskshadow Child Process Spawned
Detects any child process spawning from "Diskshadow.exe". This could be due to executing Diskshadow in interpreter mode or script mode and using the "exec" flag to launch other applications.
Diskshadow Script Mode Execution
Detects execution of "Diskshadow.exe" in script mode using the "/s" flag. Attackers often abuse "diskshadow" to execute scripts that deleted the shadow copies on the systems. Investigate the content of the scripts and its location.
Potential Proxy Execution Via Explorer.EXE From Shell Process
Detects the creation of a child "explorer.exe" process from a shell like process such as "cmd.exe" or "powershell.exe". Attackers can use "explorer.exe" for evading defense mechanisms by proxying the execution through the latter. While this is often a legitimate action, this rule can be use to hunt for anomalies. Muddy Waters threat actor was seeing using this technique.
Potential DLL Sideloading Activity Via ExtExport.EXE
Detects the execution of "Extexport.exe".A utility that is part of the Internet Explorer browser and is used to export and import various settings and data, particularly when switching between Internet Explorer and other web browsers like Firefox. It allows users to transfer bookmarks, browsing history, and other preferences from Internet Explorer to Firefox or vice versa. It can be abused as a tool to side load any DLL. If a folder is provided in the command line it'll load any DLL with one of the following names "mozcrt19.dll", "mozsqlite3.dll", or "sqlite.dll". Arbitrary DLLs can also be loaded if a specific number of flags was provided.
New Self Extracting Package Created Via IExpress.EXE
Detects the "iexpress.exe" utility creating self-extracting packages. Attackers where seen leveraging "iexpress" to compile packages on the fly via ".sed" files. Investigate the command line options provided to "iexpress" and in case of a ".sed" file, check the contents and legitimacy of it.
Microsoft Workflow Compiler Execution
Detects the execution of Microsoft Workflow Compiler, which may permit the execution of arbitrary unsigned code.
CodePage Modification Via MODE.COM
Detects a CodePage modification using the "mode.com" utility. This behavior has been used by threat actors behind Dharma ransomware.
Suspicious New Instance Of An Office COM Object
Detects an svchost process spawning an instance of an office application. This happens when the initial word application creates an instance of one of the Office COM objects such as 'Word.Application', 'Excel.Application', etc. This can be used by malicious actors to create malicious Office documents with macros on the fly. (See vba2clr project in the references)
Invocation Of Crypto-Classes From The "Cryptography" PowerShell Namespace
Detects the invocation of PowerShell commands with references to classes from the "System.Security.Cryptography" namespace. The PowerShell namespace "System.Security.Cryptography" provides classes for on-the-fly encryption and decryption. These can be used for example in decrypting malicious payload for defense evasion.
New Windows Firewall Rule Added Via New-NetFirewallRule Cmdlet
Detects calls to the "New-NetFirewallRule" cmdlet from PowerShell in order to add a new firewall rule with an "Allow" action.
Regsvr32.EXE Calling of DllRegisterServer Export Function Implicitly
Detects execution of regsvr32 with the silent flag and no other flags on a DLL located in an uncommon or potentially suspicious location. When Regsvr32 is called in such a way, it implicitly calls the DLL export function 'DllRegisterServer'.
DLL Call by Ordinal Via Rundll32.EXE
Detects calls of DLLs exports by ordinal numbers via rundll32.dll.
Rundll32.EXE Calling DllRegisterServer Export Function Explicitly
Detects when the DLL export function 'DllRegisterServer' is called in the commandline by Rundll32 explicitly where the DLL is located in a non-standard path.
Potential CommandLine Obfuscation Using Unicode Characters
Detects potential CommandLine obfuscation using unicode characters. Adversaries may attempt to make an executable or file difficult to discover or analyze by encrypting, encoding, or otherwise obfuscating its contents on the system or in transit.
Elevated System Shell Spawned
Detects when a shell program such as the Windows command prompt or PowerShell is launched with system privileges. Use this rule to hunt for potential suspicious processes.
Potential Suspicious Execution From GUID Like Folder Names
Detects potential suspicious execution of a GUID like folder name located in a suspicious location such as %TEMP% as seen being used in IcedID attacks. Use this rule to hunt for potentially suspicious activity stemming from uncommon folders.
File or Folder Permissions Modifications
Detects a file or folder's permissions being modified or tampered with.
Use Short Name Path in Command Line
Detects the use of short name paths (8.3 format) in command lines, which can be used to obfuscate paths or access restricted locations. Windows creates short 8.3 filenames (like PROGRA~1) for compatibility with MS-DOS-based or 16-bit Windows programs. When investigating, examine: - Commands using short paths to access sensitive directories or files - Web servers on Windows (especially Apache) where short filenames could bypass security controls - Correlation with other suspicious behaviors - baseline of short name usage in your environment and look for deviations
Potential Executable Run Itself As Sacrificial Process
Detects when an executable launches an identical instance of itself, a behavior often used to create a suspended “sacrificial” process for code injection or evasion. Investigate for indicators such as the process being started in suspended mode, rapid parent termination, memory manipulation (e.g., WriteProcessMemory, CreateRemoteThread), or unsigned binaries. Review command-line arguments, process ancestry, and network activity to confirm if this is legitimate behavior or process injection activity.
Arbitrary Command Execution Using WSL
Detects potential abuse of Windows Subsystem for Linux (WSL) binary as a Living of the Land binary in order to execute arbitrary Linux or Windows commands.
Microsoft Office Trusted Location Updated
Detects changes to the registry keys related to "Trusted Location" of Microsoft Office. Attackers might add additional trusted locations to avoid macro security restrictions.
Registry Set With Crypto-Classes From The "Cryptography" PowerShell Namespace
Detects the setting of a registry inside the "\Shell\Open\Command" value with PowerShell classes from the "System.Security.Cryptography" namespace. The PowerShell namespace "System.Security.Cryptography" provides classes for on-the-fly encryption and decryption. These can be used for example in decrypting malicious payload for defense evasion.