Query: detection engineering for Debugger Evasion
Matching passage: T1622 Debugger Evasion. Tactics: stealth, discovery. Description: Adversaries may employ various means to detect and avoid debuggers. Debuggers are typically used by defenders to trace and/or analyze the execution of potential malware payloads.(Citation: ProcessHacker Github) Debugger evasion may include changing behaviors based on the results of the checks for the presence of artifacts indicative of a debugged environment. Similar to [Virtualization/Sandbox Evasion](https://attack.mitre.org/techniques/T1497), if the adversary detects a debugger, they may alter their malware to disengage from the victim or conceal the core functions of the implant. They may also search for debugger artifacts before dropping secondary or additional payloads. Specific checks will vary based on the target and/or adversary. On Windows, this may involve [Native API](https://attack.mitre.org/techniques/T1106) function calls such as <code>IsDebuggerPresent()</code> and <code> NtQueryInformationProcess()</code>, or manually checking the <code>BeingDebugged</code> flag of the Process Environment Block (PEB). On Linux, this may involve querying `/proc/self/status` for the `TracerPID` field, which indicates whether or not the process is being traced by dynamic analysis tools.(Citation: Cado Security P2PInfect 2023)(Citation: Positive Technologies Hellhounds 2023) Other checks for debugging artifacts may also seek to enumerate hardware breakpoints, interrupt assembly opcodes, time checks, or measurements if exceptions are raised in the current process (assuming a present debugger would “swallow” or handle the potential error).(Citation: hasherezade debug)(Citation: AlKhaser Debug)(Citation: vxunderground debug) Malware may also leverage Structured Exception Handling (SEH) to detect debuggers by throwing an exception and detecting whether the process is suspended. SEH handles both hardware and software expectations, providing control over the exceptions including support for debugging. If a debugger is present, the program’s control will be transferred to the
Near-miss passage: T1027.010 Command Obfuscation. Tactics: stealth. Description: Adversaries may obfuscate content during command execution to impede detection. Command-line obfuscation is a method of making strings and patterns within commands and scripts more difficult to signature and analyze. This type of obfuscation can be included within commands executed by delivered payloads (e.g., [Phishing](https://attack.mitre.org/techniques/T1566) and [Drive-by Compromise](https://attack.mitre.org/techniques/T1189)) or interactively via [Command and Scripting Interpreter](https://attack.mitre.org/techniques/T1059).(Citation: Akamai JS)(Citation: Malware Monday VBE) For example, adversaries may abuse syntax that utilizes various symbols and escape characters (such as spacing, `^`, `+`. `$`, and `%`) to make commands difficult to analyze while maintaining the same intended functionality.(Citation: RC PowerShell) Many languages support built-in obfuscation in the form of base64 or URL encoding.(Citation: Microsoft PowerShellB64) Adversaries may also manually implement command obfuscation via string splitting (`“Wor”+“d.Application”`), order and casing of characters (`rev <<<'dwssap/cte/ tac'`), globing (`mkdir -p '/tmp/:&$NiA'`), as well as various tricks involving passing strings through tokens/environment variables/input streams.(Citation: Bashfuscator Command Obfuscators)(Citation: FireEye Obfuscation June 2017) Adversaries may also use tricks such as directory traversals to obfuscate references to the binary being invoked by a command (`C:\voi\pcw\..\..\Windows\tei\qs\k\..\..\..\system32\erool\..\wbem\wg\je\..\..\wmic.exe shadowcopy delete`).(Citation: Twitter Richard WMIC) Tools such as <code>Invoke-Obfuscation</code> and <code>Invoke-DOSfucation</code> have also been used to obfuscate commands.(Citation: Invoke-DOSfuscation)(Citation: Invoke-Obfuscation)