[8.18] 8.17.6 release notes (backport #6801)

docs/release-notes.asciidoc

@@ -5,6 +5,7 @@ This section summarizes the changes in each release.
 
 * <<release-notes-8.18.1, {elastic-sec} version 8.18.1>>
 * <<release-notes-8.18.0, {elastic-sec} version 8.18.0>>
+* <<release-notes-8.17.6, {elastic-sec} version 8.17.6>>
 * <<release-notes-8.17.5, {elastic-sec} version 8.17.5>>
 * <<release-notes-8.17.4, {elastic-sec} version 8.17.4>>
 * <<release-notes-8.17.3, {elastic-sec} version 8.17.3>>

docs/release-notes/8.16.asciidoc

@@ -39,6 +39,10 @@ When you install an {elastic-defend} integration or a new agent policy for this
 
 *Workaround* +
 To resolve this issue, before you add an {elastic-defend} integration to a policy in {fleet}, apply any pending prebuilt rule updates. This will prevent rule actions and exceptions from being overwritten.
+
+*Resolved* +
+This issue is fixed in {stack} versions 8.17.6, 8.18.1, and 9.0.1.
+
 ====
 // end::known-issue[]
 

docs/release-notes/8.17.asciidoc

@@ -1,6 +1,26 @@
 [[release-notes-header-8.17.0]]
 == 8.17
 
+[discrete]
+[[release-notes-8.17.6]]
+=== 8.17.6
+
+[discrete]
+[[enhancements-8.17.6]]
+==== Enhancements
+* Allows {elastic-defend} users to opt out of event-driven Memory Protection scanning using the advanced policy ({kibana-pull}218354[#218354]).
+
+[discrete]
+[[bug-fixes-8.17.6]]
+==== Fixes
+* Fixes a bug that caused installed prebuilt detection rules to upgrade to their latest available versions when you installed a new {elastic-defend} integration or {agent} policy ({kibana-pull}217959[#217959]).
+* Avoids an `IRQL_NOT_LESS_EQUAL` https://learn.microsoft.com/en-us/windows-hardware/drivers/debugger/bug-checks\--blue-screens-[bugcheck] in the {elastic-defend} driver due to an interaction with Trellix Access Protection (`mfehidk.sys`). This issue can occur when `elastic-endpoint-driver.sys` calls https://learn.microsoft.com/en-us/windows/win32/api/fwpmu/nf-fwpmu-fwpmtransactionbegin0[`FwpmTransactionBegin0`] to initialize its network driver. `FwpmTransactionBegin0` performs a synchronous RPC call to the user-mode Base Filtering Engine service. Trellix's driver intercepts this service's operations, causing `FwpmTransactionBegin0` to hang or slow significantly. This delay prevents {elastic-defend}'s driver from properly initializing in a timely manner. Subsequent system activity can invoke {elastic-defend}'s driver before it has fully initialized, leading to a `IRQL_NOT_LESS_EQUAL` bugcheck. 
++
+If you can't upgrade, you can prevent this issue from occurring by either disabling Trellix Access Protection or adding a https://docs.trellix.com/bundle/endpoint-security-10.6.0-threat-prevention-client-interface-reference-guide-windows/page/GUID-6AC245A1-5E5D-4BAF-93B0-FE7FD33571E6.html[Trellix Access Protection exclusion] for the Base Filtering Engine service (`C:\Windows\System32\svchost.exe`). This issue affects {elastic-defend} versions 8.16.0-8.16.6, 8.17.0-8.17.5, 8.18.0, and 9.0.0.
+* Resolves an unbounded kernel non-paged memory growth issue in {elastic-defend}'s kernel driver during extremely high event load situations on Windows. Systems affected by this issue would slow down or become unresponsive until the triggering event load (for example, network activity) subsided. We are only aware of this issue occurring on very busy Windows Server systems running {elastic-defend} 8.16.0 and later.
+* Allows {elastic-defend} to detect and recover from a corrupt persistent cache database.  Previously, such databases would be unusable, effectively turning off the persistent cache.
+* Reduces {elastic-defend}'s CPU usage for registry events.
+
 [discrete]
 [[release-notes-8.17.5]]
 === 8.17.5
@@ -39,6 +59,10 @@ When you install an {elastic-defend} integration or a new agent policy for this
 
 *Workaround* +
 To resolve this issue, before you add an {elastic-defend} integration to a policy in {fleet}, apply any pending prebuilt rule updates. This will prevent rule actions and exceptions from being overwritten.
+
+*Resolved* +
+This issue is fixed in {stack} versions 8.17.6, 8.18.1, and 9.0.1.
+
 ====
 // end::known-issue[]
 
@@ -140,6 +164,10 @@ When you install an {elastic-defend} integration or a new agent policy for this
 
 *Workaround* +
 To resolve this issue, before you add an {elastic-defend} integration to a policy in {fleet}, apply any pending prebuilt rule updates. This will prevent rule actions and exceptions from being overwritten.
+
+*Resolved* +
+This issue is fixed in {stack} versions 8.17.6, 8.18.1, and 9.0.1.
+
 ====
 // end::known-issue[]