Query: indicators of Downgrade Attack
Matching passage: T1689 Downgrade Attack. Tactics: defense impairment. Description: Adversaries may downgrade or use a version of system features that may be outdated, vulnerable, and/or does not support updated security controls. Downgrade attacks typically take advantage of a system’s backward compatibility to force it into less secure modes of operation. Adversaries may downgrade and use various less-secure versions of features of a system, such as [Command and Scripting Interpreter](https://attack.mitre.org/techniques/T1059) or even network protocols that can be abused to enable [Adversary-in-the-Middle](https://attack.mitre.org/techniques/T1557) or [Network Sniffing](https://attack.mitre.org/techniques/T1040).(Citation: Praetorian TLS Downgrade Attack 2014) For example, [PowerShell](https://attack.mitre.org/techniques/T1059/001) versions 5+ includes Script Block Logging (SBL), which can record executed script content. However, adversaries may attempt to execute a previous version of PowerShell that does not support SBL with the intent to impair defenses while running malicious scripts that may have otherwise been detected.(Citation: CrowdStrike downgrade attack)(Citation: Google Cloud downgrade attack)(Citation: att_def_ps_logging) Adversaries may similarly target network traffic to downgrade from an encrypted HTTPS connection to an unsecured HTTP connection that exposes network data in clear text.(Citation: Targeted SSL Stripping Attacks Are Real)(Citation: CrowdStrike Downgrade attack 2) On Windows systems, adversaries may downgrade the boot manager to a vulnerable version that bypasses Secure Boot, granting the ability to disable various operating system security mechanisms.(Citation: SafeBreach)
Near-miss passage: T1685.001 Disable or Modify Windows Event Log. Tactics: defense impairment. Description: Adversaries may disable or modify the Windows Event Log to limit data that can be leveraged for detections and audits. Windows Event Log records user and system activity such as login attempts and process creation.(Citation: EventLog_Core_Technologies) This data is used by security tools and analysts to generate detections. The EventLog service maintains event logs from various system components and applications. By default, the service automatically starts when a system powers on. An audit policy, maintained by the Local Security Policy (secpol.msc), defines which system events the EventLog service logs. Security audit policy settings can be changed by running secpol.msc, then navigating to `Security Settings\Local Policies\Audit Policy` for basic audit policy settings or `Security Settings\Advanced Audit Policy Configuration` for advanced audit policy settings.(Citation: Microsoft Audit Policy)(Citation: Microsoft Adv Security Settings) `auditpol.exe` may also be used to set audit policies.(Citation: Microsoft auditpol) Adversaries may target system-wide logging or just that of a particular application. For example, the Windows EventLog service may be disabled using the `Set-Service -Name EventLog -Status Stopped` or `sc config eventlog start=disabled` commands (followed by manually stopping the service using `Stop-Service -Name EventLog`). Additionally, the service may be disabled by modifying the "Start" value in `HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EventLog` then restarting the system for the change to take effect.(Citation: Disable_Win_Event_Logging)(Citation: disable_win_evt_logging) There are several ways to disable the EventLog service via registry key modification. Without Administrator privileges, adversaries may modify the "Start" value in the key `HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\WMI\Autologger\EventLog-Security`, then reboot the system to disable the Security EventLog.(Citation: winser19_file_overwrite_bug_twitter) W