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T1021.002 SMB/Windows Admin Shares

Adversaries may use Valid Accounts to interact with a remote network share using Server Message Block (SMB). The adversary may then perform actions as the logged-on user.

SMB is a file, printer, and serial port sharing protocol for Windows machines on the same network or domain. Adversaries may use SMB to interact with file shares, allowing them to move laterally throughout a network. Linux and macOS implementations of SMB typically use Samba.

Windows systems have hidden network shares that are accessible only to administrators and provide the ability for remote file copy and other administrative functions. Example network shares include C$, ADMIN$, and IPC$. Adversaries may use this technique in conjunction with administrator-level Valid Accounts to remotely access a networked system over SMB,1 to interact with systems using remote procedure calls (RPCs),2 transfer files, and run transferred binaries through remote Execution. Example execution techniques that rely on authenticated sessions over SMB/RPC are Scheduled Task/Job, Service Execution, and Windows Management Instrumentation. Adversaries can also use NTLM hashes to access administrator shares on systems with Pass the Hash and certain configuration and patch levels.3

Item Value
ID T1021.002
Sub-techniques T1021.001, T1021.002, T1021.003, T1021.004, T1021.005, T1021.006
Tactics TA0008
CAPEC ID CAPEC-561
Platforms Windows
Permissions required Administrator, User
Version 1.0
Created 11 February 2020
Last Modified 23 March 2020

Procedure Examples

ID Name Description
S0504 Anchor Anchor can support windows execution via SMB shares.20
G0007 APT28 APT28 has mapped network drives using Net and administrator credentials.46
G0016 APT29 APT29 has used administrative accounts to connect over SMB to targeted users.41
G0022 APT3 APT3 will copy files over to Windows Admin Shares (like ADMIN$) as part of lateral movement.40
G0050 APT32 APT32 used Net to use Windows’ hidden network shares to copy their tools to remote machines for execution.37
G0087 APT39 APT39 has used SMB for lateral movement.49
G0096 APT41 APT41 has transferred implant files using Windows Admin Shares.34
S0089 BlackEnergy BlackEnergy has run a plug-in on a victim to spread through the local network by using PsExec and accessing admin shares.24
G0108 Blue Mockingbird Blue Mockingbird has used Windows Explorer to manually copy malicious files to remote hosts over SMB.39
G0114 Chimera Chimera has used Windows admin shares to move laterally.3536
S0154 Cobalt Strike Cobalt Strike can use Window admin shares (C$ and ADMIN$) for lateral movement.15
S0608 Conficker Conficker variants spread through NetBIOS share propagation.27
S0575 Conti Conti can spread via SMB and encrypts files on different hosts, potentially compromising an entire network.1617
G0009 Deep Panda Deep Panda uses net.exe to connect to network shares using net use commands with compromised credentials.38
S0659 Diavol Diavol can spread throughout a network via SMB prior to encryption.29
S0038 Duqu Adversaries can instruct Duqu to spread laterally by copying itself to shares it has enumerated and for which it has obtained legitimate credentials (via keylogging or other means). The remote host is then infected by using the compromised credentials to schedule a task on remote machines that executes the malware.13
S0367 Emotet Emotet leverages the Admin$ share for lateral movement once the local admin password has been brute forced. 11
G0061 FIN8 FIN8 has attempted to map to C$ on enumerated hosts to test the scope of their current credentials/context.32
G0117 Fox Kitten Fox Kitten has used valid accounts to access SMB shares.52
S0698 HermeticWizard HermeticWizard can use a list of hardcoded credentials to to authenticate via NTLMSSP to the SMB shares on remote systems.30
G0004 Ke3chang Ke3chang actors have been known to copy files to the network shares of other computers to move laterally.4748
S0236 Kwampirs Kwampirs copies itself over network shares to move laterally on a victim network.31
G0032 Lazarus Group Lazarus Group malware SierraAlfa accesses the ADMIN$ share via SMB to conduct lateral movement.5051
S0532 Lucifer Lucifer can infect victims by brute forcing SMB.14
S0039 Net Lateral movement can be done with Net through net use commands to connect to the on remote systems.8
S0056 Net Crawler Net Crawler uses Windows admin shares to establish authenticated sessions to remote systems over SMB as part of lateral movement.10
S0368 NotPetya NotPetya can use PsExec, which interacts with the ADMIN$ network share to execute commands on remote systems.21229
S0365 Olympic Destroyer Olympic Destroyer uses PsExec to interact with the ADMIN$ network share to execute commands on remote systems.199
G0116 Operation Wocao Operation Wocao has used Impacket’s smbexec.py as well as accessing the C$ and IPC$ shares to move laterally.53
G0071 Orangeworm Orangeworm has copied its backdoor across open network shares, including ADMIN$, C$WINDOWS, D$WINDOWS, and E$WINDOWS.31
S0029 PsExec PsExec, a tool that has been used by adversaries, writes programs to the ADMIN$ network share to execute commands on remote systems.9
S0019 Regin The Regin malware platform can use Windows admin shares to move laterally.18
S0446 Ryuk Ryuk has used the C$ network share for lateral movement.23
G0034 Sandworm Team Sandworm Team has run net use to connect to network shares.44
S0140 Shamoon Shamoon accesses network share(s), enables share access to the target device, copies an executable payload to the target system, and uses a Scheduled Task/Job to execute the malware.28
S0603 Stuxnet Stuxnet propagates to available network shares.12
G0028 Threat Group-1314 Threat Group-1314 actors mapped network drives using net use.45
G0010 Turla Turla used net use commands to connect to lateral systems within a network.33
G0102 Wizard Spider Wizard Spider has used SMB to drop Cobalt Strike Beacon on a domain controller for lateral movement.4243
S0672 Zox Zox has the ability to use SMB for communication.25
S0350 zwShell zwShell has been copied over network shares to move laterally.26

Mitigations

ID Mitigation Description
M1037 Filter Network Traffic Consider using the host firewall to restrict file sharing communications such as SMB. 7
M1035 Limit Access to Resource Over Network Consider disabling Windows administrative shares.
M1027 Password Policies Do not reuse local administrator account passwords across systems. Ensure password complexity and uniqueness such that the passwords cannot be cracked or guessed.
M1026 Privileged Account Management Deny remote use of local admin credentials to log into systems. Do not allow domain user accounts to be in the local Administrators group multiple systems.

Detection

ID Data Source Data Component
DS0017 Command Command Execution
DS0028 Logon Session Logon Session Creation
DS0033 Network Share Network Share Access
DS0029 Network Traffic Network Connection Creation

References

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