「白帽黑客成長記」Windows提權基本原理（上）

咱們一般認爲配置得當的Windows是安全的，事實真的是這樣嗎？今天讓咱們跟隨本文做者一塊兒深刻了解Windows操做系統的黑暗角落，看看是否能獲得SYSTEM權限。

做者將使用不一樣版本的Windows來強調任何可能存在的命令行差別，請牢記由於不一樣的操做系統和版本差別會在命令行中顯現，做者試圖構造本教程，以便它適用於Windows提權的最廣泛的方式。

注：文章篇幅較長，閱讀用時約10分鐘。

必要文檔補充：

Encyclopaedia Of Windows Privilege Escalation (Brett Moore)

Windows Attacks: AT is the new black (Chris Gates & Rob Fuller)

Elevating privileges by exploiting weak folder permissions (Parvez Anwar)

譯者注：原文做者提到了meterpreter，咱們能夠把meterpreter比作sql注入利用的sqlmap，在獲得meterpreter的shell後，能夠輸入命令getsystem，自動完成提權。

在t0-t3階段，最初的信息收集方法

最開始是一個低權限的shell，這個shell多是經過遠程代碼執行、釣魚、反彈獲得的。

在最開始的階段，咱們要快速收集一些基本信息來評估咱們的環境。

第一步，找到鏈接的操做系統。

C:\Windows\system32> systeminfo | findstr /B /C:"OS Name" /C:"OS Version"
OS Name: Microsoft Windows 7 Professional
OS Version: 6.1.7601 Service Pack 1 Build 7601

接下來，咱們將看到主機名和鏈接上的對應用戶。

C:\Windows\system32> hostname
b33f
C:\Windows\system32> echo %username%
user1

如今咱們獲得了一些基本信息，而後列出其餘用戶的賬戶，並在更詳細的狀況下查看用戶信息。

這裏會看到user1不是本地組管理員。

C:\Windows\system32> net users
User accounts for \\B33F
-------------------------------------------------------------------------------
Administrator b33f Guest
user1
The command completed successfully.
C:\Windows\system32> net user user1
User name user1
Full Name
Comment
User's comment
Country code 000 (System Default)
Account active Yes
Account expires Never
Password last set 1/11/2014 7:47:14 PM
Password expires Never
Password changeable 1/11/2014 7:47:14 PM
Password required Yes
User may change password Yes
Workstations allowed All
Logon script
User profile
Home directory
Last logon 1/11/2014 8:05:09 PM
Logon hours allowed All
Local Group Memberships *Users
Global Group memberships *None
The command completed successfully.

以上是咱們目前須要瞭解的關於用戶和權限的所有內容。接下來咱們要討論的是網絡信息，鏈接的設備，以及相應規則。

首先看一下可用的網絡接口和路由表。

C:\Windows\system32> ipconfig /all
Windows IP Configuration
 Host Name . . . . . . . . . . . . : b33f
 Primary Dns Suffix . . . . . . . :
 Node Type . . . . . . . . . . . . : Hybrid
 IP Routing Enabled. . . . . . . . : No
 WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Bluetooth Network Connection:
 Media State . . . . . . . . . . . : Media disconnected
 Connection-specific DNS Suffix . :
 Description . . . . . . . . . . . : Bluetooth Device (Personal Area Network)
 Physical Address. . . . . . . . . : 0C-84-DC-62-60-29
 DHCP Enabled. . . . . . . . . . . : Yes
 Autoconfiguration Enabled . . . . : Yes
Ethernet adapter Local Area Connection:
 Connection-specific DNS Suffix . :
 Description . . . . . . . . . . . : Intel(R) PRO/1000 MT Network Connection
 Physical Address. . . . . . . . . : 00-0C-29-56-79-35
 DHCP Enabled. . . . . . . . . . . : Yes
 Autoconfiguration Enabled . . . . : Yes
 Link-local IPv6 Address . . . . . : fe80::5cd4:9caf:61c0:ba6e%11(Preferred)
 IPv4 Address. . . . . . . . . . . : 192.168.0.104(Preferred)
 Subnet Mask . . . . . . . . . . . : 255.255.255.0
 Lease Obtained. . . . . . . . . . : Saturday, January 11, 2014 3:53:55 PM
 Lease Expires . . . . . . . . . . : Sunday, January 12, 2014 3:53:55 PM
 Default Gateway . . . . . . . . . : 192.168.0.1
 DHCP Server . . . . . . . . . . . : 192.168.0.1
 DHCPv6 IAID . . . . . . . . . . . : 234884137
 DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-18-14-24-1D-00-0C-29-56-79-35
 DNS Servers . . . . . . . . . . . : 192.168.0.1
 NetBIOS over Tcpip. . . . . . . . : Enabled
C:\Windows\system32> route print
===========================================================================
Interface List
 18...0c 84 dc 62 60 29 ......Bluetooth Device (Personal Area Network)
 13...00 ff 0c 0d 4f ed ......TAP-Windows Adapter V9
 11...00 0c 29 56 79 35 ......Intel(R) PRO/1000 MT Network Connection
 1...........................Software Loopback Interface 1
 16...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter
 15...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #2
 19...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #3
 14...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface
===========================================================================
IPv4 Route Table
===========================================================================
Active Routes:
Network Destination Netmask Gateway Interface Metric
 0.0.0.0 0.0.0.0 192.168.0.1 192.168.0.104 10
 127.0.0.0 255.0.0.0 On-link 127.0.0.1 306
 127.0.0.1 255.255.255.255 On-link 127.0.0.1 306
 127.255.255.255 255.255.255.255 On-link 127.0.0.1 306
 192.168.0.0 255.255.255.0 On-link 192.168.0.104 266
 192.168.0.104 255.255.255.255 On-link 192.168.0.104 266
 192.168.0.255 255.255.255.255 On-link 192.168.0.104 266
 224.0.0.0 240.0.0.0 On-link 127.0.0.1 306
 224.0.0.0 240.0.0.0 On-link 192.168.0.104 266
 255.255.255.255 255.255.255.255 On-link 127.0.0.1 306
 255.255.255.255 255.255.255.255 On-link 192.168.0.104 266
===========================================================================
Persistent Routes:
 None
IPv6 Route Table
===========================================================================
Active Routes:
 If Metric Network Destination Gateway
 14 58 ::/0 On-link
 1 306 ::1/128 On-link
 14 58 2001::/32 On-link
 14 306 2001:0:5ef5:79fb:8d2:b4e:3f57:ff97/128
 On-link
 11 266 fe80::/64 On-link
 14 306 fe80::/64 On-link
 14 306 fe80::8d2:b4e:3f57:ff97/128
 On-link
 11 266 fe80::5cd4:9caf:61c0:ba6e/128
 On-link
 1 306 ff00::/8 On-link
 14 306 ff00::/8 On-link
 11 266 ff00::/8 On-link
===========================================================================
Persistent Routes:
 None

arp -A顯示了全部可用接口的arp(地址解析協議)緩存表。

C:\Windows\system32> arp -A
Interface: 192.168.0.104 --- 0xb
 Internet Address Physical Address Type
 192.168.0.1 90-94-e4-c5-b0-46 dynamic
 192.168.0.101 ac-22-0b-af-bb-43 dynamic
 192.168.0.255 ff-ff-ff-ff-ff-ff static
 224.0.0.22 01-00-5e-00-00-16 static
 224.0.0.251 01-00-5e-00-00-fb static
 224.0.0.252 01-00-5e-00-00-fc static
 239.255.255.250 01-00-5e-7f-ff-fa static
 255.255.255.255 ff-ff-ff-ff-ff-ff static

這就使咱們瞭解了活動網絡鏈接和防火牆規則。

C:\Windows\system32> netstat -ano
Active Connections
 Proto Local Address Foreign Address State PID
 TCP 0.0.0.0:135 0.0.0.0:0 LISTENING 684
 TCP 0.0.0.0:445 0.0.0.0:0 LISTENING 4
 TCP 0.0.0.0:5357 0.0.0.0:0 LISTENING 4
 TCP 127.0.0.1:5354 0.0.0.0:0 LISTENING 1400
 TCP 192.168.0.104:139 0.0.0.0:0 LISTENING 4
 TCP [::]:135 [::]:0 LISTENING 684
 TCP [::]:445 [::]:0 LISTENING 4
 TCP [::]:5357 [::]:0 LISTENING 4
 UDP 0.0.0.0:5355 *:* 1100
 UDP 0.0.0.0:52282 *:* 976
 UDP 0.0.0.0:55202 *:* 2956
 UDP 0.0.0.0:59797 *:* 1400
 UDP 127.0.0.1:1900 *:* 2956
 UDP 127.0.0.1:65435 *:* 2956
 UDP 192.168.0.104:137 *:* 4
 UDP 192.168.0.104:138 *:* 4
 UDP 192.168.0.104:1900 *:* 2956
 UDP 192.168.0.104:5353 *:* 1400
 UDP 192.168.0.104:65434 *:* 2956
 UDP [::]:5355 *:* 1100
 UDP [::]:52281 *:* 976
 UDP [::]:52283 *:* 976
 UDP [::]:55203 *:* 2956
 UDP [::]:59798 *:* 1400
 UDP [::1]:1900 *:* 2956
 UDP [::1]:5353 *:* 1400
 UDP [::1]:65433 *:* 2956
 UDP [fe80::5cd4:9caf:61c0:ba6e%11]:1900 *:* 2956
 UDP [fe80::5cd4:9caf:61c0:ba6e%11]:65432 *:* 2956

如下兩個netsh命令是在不一樣操做系統的命令示例。

netsh firewall命令只能從XP SP2和以上版本運行。

C:\Windows\system32> netsh firewall show state
Firewall status:
-------------------------------------------------------------------
Profile = Standard
Operational mode = Enable
Exception mode = Enable
Multicast/broadcast response mode = Enable
Notification mode = Enable
Group policy version = Windows Firewall
Remote admin mode = Disable
Ports currently open on all network interfaces:
Port Protocol Version Program
-------------------------------------------------------------------
No ports are currently open on all network interfaces.
C:\Windows\system32> netsh firewall show config
Domain profile configuration:
-------------------------------------------------------------------
Operational mode = Enable
Exception mode = Enable
Multicast/broadcast response mode = Enable
Notification mode = Enable
Allowed programs configuration for Domain profile:
Mode Traffic direction Name / Program
-------------------------------------------------------------------
Port configuration for Domain profile:
Port Protocol Mode Traffic direction Name
-------------------------------------------------------------------
ICMP configuration for Domain profile:
Mode Type Description
-------------------------------------------------------------------
Enable 2 Allow outbound packet too big
Standard profile configuration (current):
-------------------------------------------------------------------
Operational mode = Enable
Exception mode = Enable
Multicast/broadcast response mode = Enable
Notification mode = Enable
Service configuration for Standard profile:
Mode Customized Name
-------------------------------------------------------------------
Enable No Network Discovery
Allowed programs configuration for Standard profile:
Mode Traffic direction Name / Program
-------------------------------------------------------------------
Enable Inbound COMRaider / E:\comraider\comraider.exe
Enable Inbound nc.exe / C:\users\b33f\desktop\nc.exe
Port configuration for Standard profile:
Port Protocol Mode Traffic direction Name
-------------------------------------------------------------------
ICMP configuration for Standard profile:
Mode Type Description
-------------------------------------------------------------------
Enable 2 Allow outbound packet too big
Log configuration:
-------------------------------------------------------------------
File location = C:\Windows\system32\LogFiles\Firewall\pfirewall.log
Max file size = 4096 KB
Dropped packets = Disable
Connections = Disable

最後，咱們將簡要地看一下在這個設備上的運行內容，好比計劃任務、運行進程、啓動服務和安裝的驅動程序。

這將顯示全部調度任務的詳細輸出，下面您能夠看到單個任務的示例輸出。

C:\Windows\system32> schtasks /query /fo LIST /v
Folder: \Microsoft\Windows Defender
HostName: B33F
TaskName: \Microsoft\Windows Defender\MP Scheduled Scan
Next Run Time: 1/22/2014 5:11:13 AM
Status: Ready
Logon Mode: Interactive/Background
Last Run Time: N/A
Last Result: 1
Author: N/A
Task To Run: c:\program files\windows defender\MpCmdRun.exe Scan -ScheduleJob
 -WinTask -RestrictPrivilegesScan
Start In: N/A
Comment: Scheduled Scan
Scheduled Task State: Enabled
Idle Time: Only Start If Idle for 1 minutes, If Not Idle Retry For 240 minutes
Power Management: No Start On Batteries
Run As User: SYSTEM
Delete Task If Not Rescheduled: Enabled
Stop Task If Runs X Hours and X Mins: 72:00:00
Schedule: Scheduling data is not available in this format.
Schedule Type: Daily
Start Time: 5:11:13 AM
Start Date: 1/1/2000
End Date: 1/1/2100
Days: Every 1 day(s)
Months: N/A
Repeat: Every: Disabled
Repeat: Until: Time: Disabled
Repeat: Until: Duration: Disabled
Repeat: Stop If Still Running: Disabled
[..Snip..]
# tasklist命令顯示了正在運行的進程以及啓動服務。
C:\Windows\system32> tasklist /SVC
Image Name PID Services
========================= ======== ============================================
System Idle Process 0 N/A
System 4 N/A
smss.exe 244 N/A
csrss.exe 332 N/A
csrss.exe 372 N/A
wininit.exe 380 N/A
winlogon.exe 428 N/A
services.exe 476 N/A
lsass.exe 484 SamSs
lsm.exe 496 N/A
svchost.exe 588 DcomLaunch, PlugPlay, Power
svchost.exe 668 RpcEptMapper, RpcSs
svchost.exe 760 Audiosrv, Dhcp, eventlog,
 HomeGroupProvider, lmhosts, wscsvc
svchost.exe 800 AudioEndpointBuilder, CscService, Netman,
 SysMain, TrkWks, UxSms, WdiSystemHost,
 wudfsvc
svchost.exe 836 AeLookupSvc, BITS, gpsvc, iphlpsvc,
 LanmanServer, MMCSS, ProfSvc, Schedule,
 seclogon, SENS, ShellHWDetection, Themes,
 Winmgmt, wuauserv
audiodg.exe 916 N/A
svchost.exe 992 EventSystem, fdPHost, netprofm, nsi,
 WdiServiceHost, WinHttpAutoProxySvc
svchost.exe 1104 CryptSvc, Dnscache, LanmanWorkstation,
 NlaSvc
spoolsv.exe 1244 Spooler
svchost.exe 1272 BFE, DPS, MpsSvc
mDNSResponder.exe 1400 Bonjour Service
taskhost.exe 1504 N/A
taskeng.exe 1556 N/A
vmtoolsd.exe 1580 VMTools
dwm.exe 1660 N/A
explorer.exe 1668 N/A
vmware-usbarbitrator.exe 1768 VMUSBArbService
TPAutoConnSvc.exe 1712 TPAutoConnSvc
[..Snip..]
C:\Windows\system32> net start
These Windows services are started:
 Application Experience
 Application Information
 Background Intelligent Transfer Service
 Base Filtering Engine
 Bluetooth Support Service
 Bonjour Service
 COM+ Event System
 COM+ System Application
 Cryptographic Services
 DCOM Server Process Launcher
 Desktop Window Manager Session Manager
 DHCP Client
 Diagnostic Policy Service
 Diagnostic Service Host
 Diagnostic System Host
 Distributed Link Tracking Client
 Distributed Transaction Coordinator
 DNS Client
 Function Discovery Provider Host
 Function Discovery Resource Publication
 Group Policy Client
[..Snip..]
# DRIVERQUERY有時是有用的，由於一些第三方驅動，即便是信譽良好的公司，也比瑞士奶酪上的洞多。這是可能的，由於ring0的利用是在大多數人的專長技能以外。
C:\Windows\system32> DRIVERQUERY
Module Name Display Name Driver Type Link Date
============ ====================== ============= ======================
1394ohci 1394 OHCI Compliant Ho Kernel 11/20/2010 6:01:11 PM
ACPI Microsoft ACPI Driver Kernel 11/20/2010 4:37:52 PM
AcpiPmi ACPI Power Meter Drive Kernel 11/20/2010 4:47:55 PM
adp94xx adp94xx Kernel 12/6/2008 7:59:55 AM
adpahci adpahci Kernel 5/2/2007 1:29:26 AM
adpu320 adpu320 Kernel 2/28/2007 8:03:08 AM
AFD Ancillary Function Dri Kernel 11/20/2010 4:40:00 PM
agp440 Intel AGP Bus Filter Kernel 7/14/2009 7:25:36 AM
aic78xx aic78xx Kernel 4/12/2006 8:20:11 AM
aliide aliide Kernel 7/14/2009 7:11:17 AM
amdagp AMD AGP Bus Filter Dri Kernel 7/14/2009 7:25:36 AM
amdide amdide Kernel 7/14/2009 7:11:19 AM
AmdK8 AMD K8 Processor Drive Kernel 7/14/2009 7:11:03 AM
AmdPPM AMD Processor Driver Kernel 7/14/2009 7:11:03 AM
amdsata amdsata Kernel 3/19/2010 9:08:27 AM
amdsbs amdsbs Kernel 3/21/2009 2:35:26 AM
amdxata amdxata Kernel 3/20/2010 12:19:01 AM
AppID AppID Driver Kernel 11/20/2010 5:29:48 PM
arc arc Kernel 5/25/2007 5:31:06 AM
[..Snip..]

 

在t4階段，神祕藝術之WMIC

WMIC（Windows Management Instrumentation Command-Line，Windows管理工具命令行），是Windows最有用的命令行工具之一。

WMIC對於信息收集和滲透是很是實用的，並且輸出內容有不少值得期待的地方。全面解釋WMIC的使用將須要一個教程，因爲格式化的問題，WMIC有些輸出將很難顯示。

下面列出兩個文章，對於WMIC是很是值得閱讀的：

• Command-Line Ninjitsu (SynJunkie)
• Windows WMIC Command Line (ComputerHope)

 

一些默認配置的Windows並不容許訪問WMIC，除非是用戶在Windows的管理組，從虛擬機測試來看，任何版本的Windows XP的低權限用戶並不能訪問WMIC。相反的，默認配置的Windows 7專業版和Windows 8企業版容許低權限的用戶訪問WMIC並查詢操做系統版本。

這正是咱們所須要的，由於咱們正在使用WMIC來收集關於目標機的信息。關於WMIC的選項，列出了下面可用的命令行：

C:\Windows\system32> wmic /?
[global switches] 
The following global switches are available:
/NAMESPACE Path for the namespace the alias operate against.
/ROLE Path for the role containing the alias definitions.
/NODE Servers the alias will operate against.
/IMPLEVEL Client impersonation level.
/AUTHLEVEL Client authentication level.
/LOCALE Language id the client should use.
/PRIVILEGES Enable or disable all privileges.
/TRACE Outputs debugging information to stderr.
/RECORD Logs all input commands and output.
/INTERACTIVE Sets or resets the interactive mode.
/FAILFAST Sets or resets the FailFast mode.
/USER User to be used during the session.
/PASSWORD Password to be used for session login.
/OUTPUT Specifies the mode for output redirection.
/APPEND Specifies the mode for output redirection.
/AGGREGATE Sets or resets aggregate mode.
/AUTHORITY Specifies the for the connection.
/?[:<BRIEF|FULL>] Usage information.
For more information on a specific global switch, type: switch-name /?
The following alias/es are available in the current role:
ALIAS - Access to the aliases available on the local system
BASEBOARD - Base board (also known as a motherboard or system board) management.
BIOS - Basic input/output services (BIOS) management.
BOOTCONFIG - Boot configuration management.
CDROM - CD-ROM management.
COMPUTERSYSTEM - Computer system management.
CPU - CPU management.
CSPRODUCT - Computer system product information from SMBIOS.
DATAFILE - DataFile Management.
DCOMAPP - DCOM Application management.
DESKTOP - User's Desktop management.
DESKTOPMONITOR - Desktop Monitor management.
DEVICEMEMORYADDRESS - Device memory addresses management.
DISKDRIVE - Physical disk drive management.
DISKQUOTA - Disk space usage for NTFS volumes.
DMACHANNEL - Direct memory access (DMA) channel management.
ENVIRONMENT - System environment settings management.
FSDIR - Filesystem directory entry management.
GROUP - Group account management.
IDECONTROLLER - IDE Controller management.
IRQ - Interrupt request line (IRQ) management.
JOB - Provides access to the jobs scheduled using the schedule service.
LOADORDER - Management of system services that define execution dependencies.
LOGICALDISK - Local storage device management.
LOGON - LOGON Sessions.
MEMCACHE - Cache memory management.
MEMORYCHIP - Memory chip information.
MEMPHYSICAL - Computer system's physical memory management.
NETCLIENT - Network Client management.
NETLOGIN - Network login information (of a particular user) management.
NETPROTOCOL - Protocols (and their network characteristics) management.
NETUSE - Active network connection management.
NIC - Network Interface Controller (NIC) management.
NICCONFIG - Network adapter management.
NTDOMAIN - NT Domain management.
NTEVENT - Entries in the NT Event Log.
NTEVENTLOG - NT eventlog file management.
ONBOARDDEVICE - Management of common adapter devices built into the motherboard (system board).
OS - Installed Operating System/s management.
PAGEFILE - Virtual memory file swapping management.
PAGEFILESET - Page file settings management.
PARTITION - Management of partitioned areas of a physical disk.
PORT - I/O port management.
PORTCONNECTOR - Physical connection ports management.
PRINTER - Printer device management.
PRINTERCONFIG - Printer device configuration management.
PRINTJOB - Print job management.
PROCESS - Process management.
PRODUCT - Installation package task management.
QFE - Quick Fix Engineering.
QUOTASETTING - Setting information for disk quotas on a volume.
RDACCOUNT - Remote Desktop connection permission management.
RDNIC - Remote Desktop connection management on a specific network adapter.
RDPERMISSIONS - Permissions to a specific Remote Desktop connection.
RDTOGGLE - Turning Remote Desktop listener on or off remotely.
RECOVEROS - Information that will be gathered from memory when the operating system fails.
REGISTRY - Computer system registry management.
SCSICONTROLLER - SCSI Controller management.
SERVER - Server information management.
SERVICE - Service application management.
SHADOWCOPY - Shadow copy management.
SHADOWSTORAGE - Shadow copy storage area management.
SHARE - Shared resource management.
SOFTWAREELEMENT - Management of the elements of a software product installed on a system.
SOFTWAREFEATURE - Management of software product subsets of SoftwareElement.
SOUNDDEV - Sound Device management.
STARTUP - Management of commands that run automatically when users log onto the computer 
 system.
SYSACCOUNT - System account management.
SYSDRIVER - Management of the system driver for a base service.
SYSTEMENCLOSURE - Physical system enclosure management.
SYSTEMSLOT - Management of physical connection points including ports, slots and 
 peripherals, and proprietary connections points.
TAPEDRIVE - Tape drive management.
TEMPERATURE - Data management of a temperature sensor (electronic thermometer).
TIMEZONE - Time zone data management.
UPS - Uninterruptible power supply (UPS) management.
USERACCOUNT - User account management.
VOLTAGE - Voltage sensor (electronic voltmeter) data management.
VOLUME - Local storage volume management.
VOLUMEQUOTASETTING - Associates the disk quota setting with a specific disk volume.
VOLUMEUSERQUOTA - Per user storage volume quota management.
WMISET - WMI service operational parameters management.
For more information on a specific alias, type: alias /?
CLASS - Escapes to full WMI schema.
PATH - Escapes to full WMI object paths.
CONTEXT - Displays the state of all the global switches.
QUIT/EXIT - Exits the program.
For more information on CLASS/PATH/CONTEXT, type: (CLASS | PATH | CONTEXT) /?

爲了簡化操做，我已經建立了一個腳本，能夠在目標機器上使用WMIC提取如下信息：流程、服務、用戶賬號、用戶組、網絡接口、硬盤信息、網絡共享信息、安裝Windows補丁、程序在啓動運行、安裝的軟件列表、操做系統、時區信息。

經過各類標誌和參數來提取有價值的信息，若是有人想要添加到列表中，請在下面留下評論。使用內置的輸出特性，腳本將把全部結果寫入可讀的html文件。

腳本地址：

http://www.fuzzysecurity.com/tutorials/files/wmic_info.rar

輸出頁面：

http://www.fuzzysecurity.com/tutorials/files/Win7.html

以上是今天的內容，你們看懂了嗎？下期咱們將繼續分享Windows提權基本原理的相關內容，請你們及時關注。