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[Tuning] Improve Performance (#2953)

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* [Tuning] Improve Performance

Remote Computer Account DnsHostName Update : sequence not needed, removed auth event to improve rule execution time.

Potential Remote Credential Access via Registry : removed sequence, since user.id is reported as std user SID (svchost is impersonating a remote user), and reduced file.path to known bad (based on observed TPs)

* Update privilege_escalation_suspicious_dnshostname_update.toml

* ++

* ++

---------

Co-authored-by: Jonhnathan <26856693+w0rk3r@users.noreply.github.com>

(cherry picked from commit 5e801b2edf)
This commit is contained in:
Samirbous
2023-08-21 16:23:34 +01:00
committed by github-actions[bot]
parent 32f4fe26ba
commit 3534b37ba6
2 changed files with 8 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files
rules/windows/credential_access_remote_sam_secretsdump.toml
+5 -13
View File
@@ -4,7 +4,7 @@ integration = ["endpoint", "system", "windows"]
maturity = "production"
min_stack_comments = "New fields added: required_fields, related_integrations, setup"
min_stack_version = "8.3.0"
updated_date = "2023/06/22"
updated_date = "2023/07/21"
[rule]
author = ["Elastic"]
@@ -73,22 +73,14 @@ tags = [
"Tactic: Credential Access",
"Resources: Investigation Guide",
]
timestamp_override = "event.ingested"
type = "eql"
query = '''
sequence by host.id, user.id with maxspan=1m
[authentication where
event.outcome == "success" and event.action == "logged-in" and
winlog.logon.type == "Network" and not user.name == "ANONYMOUS LOGON" and
not user.domain == "NT AUTHORITY" and source.ip != "127.0.0.1" and source.ip !="::1"]
[file where event.action == "creation" and process.name : "svchost.exe" and
file where host.os.type == "windows" and
event.action == "creation" and process.name : "svchost.exe" and
file.Ext.header_bytes : "72656766*" and user.id : ("S-1-5-21-*", "S-1-12-1-*") and file.size >= 30000 and
not file.path :
("?:\\Windows\\system32\\HKEY_LOCAL_MACHINE_SOFTWARE_Microsoft_*.registry",
"?:\\Users\\*\\AppData\\Local\\Microsoft\\Windows\\UsrClass.dat.LOG?",
"?:\\Users\\*\\AppData\\Local\\Microsoft\\Windows\\UsrClass.dat",
"?:\\Users\\*\\ntuser.dat.LOG?",
"?:\\Users\\*\\NTUSER.DAT")]
file.path : ("?:\\Windows\\system32\\*.tmp", "?:\\WINDOWS\\Temp\\*.tmp")
'''
rules/windows/privilege_escalation_suspicious_dnshostname_update.toml
+3 -10
View File
@@ -4,7 +4,7 @@ integration = ["system", "windows"]
maturity = "production"
min_stack_comments = "New fields added: required_fields, related_integrations, setup"
min_stack_version = "8.3.0"
updated_date = "2023/06/22"
updated_date = "2023/07/21"
[rule]
author = ["Elastic"]
@@ -27,24 +27,17 @@ risk_score = 73
rule_id = "6bed021a-0afb-461c-acbe-ffdb9574d3f3"
severity = "high"
tags = ["Domain: Endpoint", "OS: Windows", "Use Case: Threat Detection", "Tactic: Privilege Escalation", "Use Case: Active Directory Monitoring", "Data Source: Active Directory", "Use Case: Vulnerability"]
timestamp_override = "event.ingested"
type = "eql"
query = '''
sequence by winlog.computer_name with maxspan=5m
[authentication where event.action == "logged-in" and
winlog.logon.type == "Network" and event.outcome == "success" and
not user.name == "ANONYMOUS LOGON" and not winlog.event_data.SubjectUserName : "*$" and
not user.domain == "NT AUTHORITY" and source.ip != "127.0.0.1" and source.ip !="::1"] by winlog.event_data.TargetLogonId
[iam where event.action == "changed-computer-account" and
iam where event.action == "changed-computer-account" and user.id : ("S-1-5-21-*", "S-1-12-1-*") and
/* if DnsHostName value equal a DC DNS hostname then it's highly suspicious */
winlog.event_data.DnsHostName : "??*" and
/* exclude FPs where DnsHostName starts with the ComputerName that was changed */
not startswith~(winlog.event_data.DnsHostName, substring(winlog.event_data.TargetUserName, 0, length(winlog.event_data.TargetUserName) - 1))
] by winlog.event_data.SubjectLogonId
'''