Query: EDR alert: possible Unix Shell Configuration Modification (T1546.004)
Matching passage: T1546.004 Unix Shell Configuration Modification. Tactics: privilege escalation, persistence. Description: Adversaries may establish persistence through executing malicious commands triggered by a user’s shell. User [Unix Shell](https://attack.mitre.org/techniques/T1059/004)s execute several configuration scripts at different points throughout the session based on events. For example, when a user opens a command-line interface or remotely logs in (such as via SSH) a login shell is initiated. The login shell executes scripts from the system (<code>/etc</code>) and the user’s home directory (<code>~/</code>) to configure the environment. All login shells on a system use /etc/profile when initiated. These configuration scripts run at the permission level of their directory and are often used to set environment variables, create aliases, and customize the user’s environment. When the shell exits or terminates, additional shell scripts are executed to ensure the shell exits appropriately. Adversaries may attempt to establish persistence by inserting commands into scripts automatically executed by shells. Using bash as an example, the default shell for most GNU/Linux systems, adversaries may add commands that launch malicious binaries into the <code>/etc/profile</code> and <code>/etc/profile.d</code> files.(Citation: intezer-kaiji-malware)(Citation: bencane blog bashrc) These files typically require root permissions to modify and are executed each time any shell on a system launches. For user level permissions, adversaries can insert malicious commands into <code>~/.bash_profile</code>, <code>~/.bash_login</code>, or <code>~/.profile</code> which are sourced when a user opens a command-line interface or connects remotely.(Citation: anomali-rocke-tactics)(Citation: Linux manual bash invocation) Since the system only executes the first existing file in the listed order, adversaries have used <code>~/.bash_profile</code> to ensure execution. Adversaries have also leveraged the <code>~/.bashrc</code> file which is additionally executed if the connection is established remotely or
Near-miss passage: T1546.012 Image File Execution Options Injection. Tactics: privilege escalation, persistence. Description: Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by Image File Execution Options (IFEO) debuggers. IFEOs enable a developer to attach a debugger to an application. When a process is created, a debugger present in an application’s IFEO will be prepended to the application’s name, effectively launching the new process under the debugger (e.g., <code>C:\dbg\ntsd.exe -g notepad.exe</code>).(Citation: Microsoft Dev Blog IFEO Mar 2010) IFEOs can be set directly via the Registry or in Global Flags via the GFlags tool.(Citation: Microsoft GFlags Mar 2017) IFEOs are represented as <code>Debugger</code> values in the Registry under <code>HKLM\SOFTWARE{\Wow6432Node}\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\<executable></code> where <code>&lt;executable&gt;</code> is the binary on which the debugger is attached.(Citation: Microsoft Dev Blog IFEO Mar 2010) IFEOs can also enable an arbitrary monitor program to be launched when a specified program silently exits (i.e. is prematurely terminated by itself or a second, non kernel-mode process).(Citation: Microsoft Silent Process Exit NOV 2017)(Citation: Oddvar Moe IFEO APR 2018) Similar to debuggers, silent exit monitoring can be enabled through GFlags and/or by directly modifying IFEO and silent process exit Registry values in <code>HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SilentProcessExit\</code>.(Citation: Microsoft Silent Process Exit NOV 2017)(Citation: Oddvar Moe IFEO APR 2018) Similar to [Accessibility Features](https://attack.mitre.org/techniques/T1546/008), on Windows Vista and later as well as Windows Server 2008 and later, a Registry key may be modified that configures "cmd.exe," or another program that provides backdoor access, as a "debugger" for an accessibility program (ex: utilman.exe). After the Registry is modified, pressing the appropriate key combination at the login screen while at the keyboard or when connecte