| ID | Technique | Tactic |
|---|---|---|
| T1548.002 | Bypass User Account Control | Defense Evasion |
Detection: Windows UAC Bypass Suspicious Escalation Behavior
Description
The following analytic detects when a process spawns an executable known for User Account Control (UAC) bypass exploitation and subsequently monitors for any child processes with a higher integrity level than the original process. This detection leverages Sysmon EventID 1 data, focusing on process integrity levels and known UAC bypass executables. This activity is significant as it may indicate an attacker has successfully used a UAC bypass exploit to escalate privileges. If confirmed malicious, the attacker could gain elevated privileges, potentially leading to further system compromise and persistent access.
Search
1
2| tstats `security_content_summariesonly`
3 count max(_time) as lastTime
4
5FROM datamodel=Endpoint.Processes WHERE
6
7Processes.process_integrity_level IN (
8 "low",
9 "medium"
10)
11
12BY Processes.action Processes.dest Processes.original_file_name
13 Processes.parent_process Processes.parent_process_exec
14 Processes.parent_process_guid Processes.parent_process_id
15 Processes.parent_process_name Processes.parent_process_path
16 Processes.process Processes.process_exec Processes.process_guid
17 Processes.process_hash Processes.process_id
18 Processes.process_integrity_level Processes.process_name
19 Processes.process_path Processes.user
20 Processes.user_id Processes.vendor_product
21
22
23| `drop_dm_object_name(Processes)`
24
25
26| eval original_integrity_level = CASE(
27 match(process_integrity_level,"low"),1,
28 match(process_integrity_level,"medium"),2,
29 match(process_integrity_level,"high"),3,
30 match(process_integrity_level,"system"),4,
31 true(),0
32 )
33
34| rename process_guid as join_guid_1,
35 process* as parent_process*
36
37
38| join max=0 dest join_guid_1 [
39
40| tstats `security_content_summariesonly`
41 count min(_time) as firstTime
42 FROM datamodel=Endpoint.Processes WHERE
43
44 Processes.process_integrity_level IN (
45 "high",
46 "system"
47 )
48 Processes.process_name IN (`uacbypass_process_name`)
49
50 BY Processes.dest Processes.parent_process_guid
51 Processes.process_name Processes.process_guid
52
53
54| `drop_dm_object_name(Processes)`
55
56| rename parent_process_guid as join_guid_1,
57 process_guid as join_guid_2,
58 process_name as uac_process_name
59]
60
61
62| join max=0 dest join_guid_2 [
63
64| tstats `security_content_summariesonly`
65 count min(_time) as firstTime
66 FROM datamodel=Endpoint.Processes WHERE
67
68 Processes.parent_process_name IN (`uacbypass_process_name`)
69 Processes.process_integrity_level IN (
70 "high",
71 "system"
72 )
73 BY Processes.dest Processes.parent_process_guid
74 Processes.process_name Processes.process
75 Processes.process_guid Processes.process_path
76 Processes.process_integrity_level Processes.process_current_directory
77
78
79| `drop_dm_object_name(Processes)`
80
81
82| rename parent_process_guid as join_guid_2
83
84
85| eval elevated_integrity_level = CASE(
86 match(process_integrity_level,"low"),1,
87 match(process_integrity_level,"medium"),2,
88 match(process_integrity_level,"high"),3,
89 match(process_integrity_level,"system"),4,
90 true(),0
91 )
92]
93
94| where elevated_integrity_level > original_integrity_level
95
96| `security_content_ctime(firstTime)`
97
98| `security_content_ctime(lastTime)`
99
100| `windows_uac_bypass_suspicious_escalation_behavior_filter`
Data Source
| Name | Platform | Sourcetype | Source |
|---|---|---|---|
| Sysmon EventID 1 |  Windows |
'XmlWinEventLog' |
'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' |
Macros Used
| Name | Value |
|---|---|
| security_content_ctime | convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$) |
| windows_uac_bypass_suspicious_escalation_behavior_filter | search * |
windows_uac_bypass_suspicious_escalation_behavior_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
MITRE ATT&CK
Kill Chain Phases
NIST
CIS
Threat Actors
Exploitation
DE.CM
CIS 10
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
| Setting | Value |
|---|---|
| Disabled | true |
| Cron Schedule | 0 * * * * |
| Earliest Time | -70m@m |
| Latest Time | -10m@m |
| Schedule Window | auto |
| Creates Notable | Yes |
| Rule Title | %name% |
| Rule Description | %description% |
| Notable Event Fields | user, dest |
| Creates Risk Event | True |
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.
Implementation
Target environment must ingest sysmon data, specifically Event ID 1 with process integrity level data.
Known False Positives
Including Werfault.exe may cause some unintended false positives related to normal application faulting, but is used in a number of UAC bypass techniques.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message:
A UAC bypass behavior was detected by process $parent_process_name$ on host $dest$ by $user$.
| Risk Object | Risk Object Type | Risk Score | Threat Objects |
|---|---|---|---|
| dest | system | 50 | process_name, parent_process_name |
| user | user | 50 | process_name, parent_process_name |
References
-
https://hadess.io/user-account-control-uncontrol-mastering-the-art-of-bypassing-windows-uac/
-
https://enigma0x3.net/2016/08/15/fileless-uac-bypass-using-eventvwr-exe-and-registry-hijacking/
Detection Testing
| Test Type | Status | Dataset | Source | Sourcetype |
|---|---|---|---|---|
| Validation | ✅ Passing | N/A | N/A | N/A |
| Unit | ✅ Passing | Dataset | XmlWinEventLog:Microsoft-Windows-Sysmon/Operational |
XmlWinEventLog |
| Integration | ✅ Passing | Dataset | XmlWinEventLog:Microsoft-Windows-Sysmon/Operational |
XmlWinEventLog |
Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI.
Alternatively you can replay a dataset into a Splunk Attack Range
Source: GitHub | Version: 12