T1562.006 Indicator Blocking

T1562.006 Indicator Blocking

Sub-technique of: T1562

High-Level Description

An adversary may attempt to block indicators or events typically captured by sensors from being gathered and analyzed. This could include maliciously redirecting or even disabling host-based sensors, such as Event Tracing for Windows (ETW), by tampering settings that control the collection and flow of event telemetry. These settings may be stored on the system in configuration files and/or in the Registry as well as being accessible via administrative utilities such as PowerShell or Windows Management Instrumentation.

For example, adversaries may modify the File value in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EventLog\Security to hide their malicious actions in a new or different .evtx log file. This action does not require a system reboot and takes effect immediately.

ETW interruption can be achieved multiple ways, however most directly by defining conditions using the PowerShell Set-EtwTraceProvider cmdlet or by interfacing directly with the Registry to make alterations.

In the case of network-based reporting of indicators, an adversary may block traffic associated with reporting to prevent central analysis. This may be accomplished by many means, such as stopping a local process responsible for forwarding telemetry and/or creating a host-based firewall rule to block traffic to specific hosts responsible for aggregating events, such as security information and event management (SIEM) products.

In Linux environments, adversaries may disable or reconfigure log processing tools such as syslog or nxlog to inhibit detection and monitoring capabilities to facilitate follow on behaviors. ESXi also leverages syslog, which can be reconfigured via commands such as esxcli system syslog config set and esxcli system syslog config reload.

Kill Chain Phase

• Defense Evasion (TA0005)

Platforms: Windows, macOS, Linux, ESXi

What to Check

• Identify if Indicator Blocking technique is applicable to target environment
• Check Windows systems for indicators of Indicator Blocking
• Check macOS systems for indicators of Indicator Blocking
• Check Linux systems for indicators of Indicator Blocking
• Verify mitigations are bypassed or absent (3 known mitigations)
• Assess detection coverage (1 detection strategies)

How to Test

Atomic Red Team Tests

The following tests are from Atomic Red Team and provide actionable ways to test this technique:

Atomic Test 1: Auditing Configuration Changes on Linux Host

Emulates modification of auditd configuration files