Network Share Discovery

Networks often contain shared network drives and folders that enable users to access file directories on various systems across a network.

Windows

File sharing over a Windows network occurs over the SMB protocol. [1] [2]

Net can be used to query a remote system for available shared drives using the net view \remotesystem command. It can also be used to query shared drives on the local system using net share.

Adversaries may look for folders and drives shared on remote systems as a means of identifying sources of information to gather as a precursor for Collection and to identify potential systems of interest for Lateral Movement.

Mac

On Mac, locally mounted shares can be viewed with the df -aH command.

Cloud

Cloud virtual networks may contain remote network shares or file storage services accessible to an adversary after they have obtained access to a system. For example, AWS, GCP, and Azure support creation of Network File System (NFS) shares and Server Message Block (SMB) shares that may be mapped on endpoint or cloud-based systems.[3][4]

ID: T1135
Tactic: Discovery
Platform: macOS, Windows, AWS, GCP, Azure
Permissions Required: User
Data Sources: Process monitoring, Process command-line parameters, Network protocol analysis, Process use of network
CAPEC ID: CAPEC-643
Contributors: Praetorian
Version: 2.0

Procedure Examples

Name Description
APT1 APT1 listed connected network shares. [20]
APT41 APT41 used the net share command as part of network reconnaissance. [22]
Cobalt Strike Cobalt Strike can query shared drives on the local system. [8]
Dragonfly 2.0 Dragonfly 2.0 identified and browsed file servers in the victim network, sometimes , viewing files pertaining to ICS or Supervisory Control and Data Acquisition (SCADA) systems. [17] [18]
Empire Empire can find shared drives on the local system. [9]
InvisiMole InvisiMole can gather network share information. [10]
Koadic Koadic can scan local network for open SMB. [6]
Kwampirs Kwampirs collects a list of network shares with the command net share. [12]
MURKYTOP MURKYTOP has the capability to retrieve information about shares on remote hosts. [11]
Net The net view \remotesystem and net share commands in Net can be used to find shared drives and directories on remote and local systems respectively. [5]
Olympic Destroyer Olympic Destroyer will attempt to enumerate mapped network shares to later attempt to wipe all files on those shares. [16]
OSInfo OSInfo discovers shares on the network [14]
PlugX PlugX has a module to enumerate network shares. [15]
Pupy Pupy can list local and remote shared drives and folders over SMB. [7]
Sowbug Sowbug listed remote shared drives that were accessible from a victim. [19]
Tropic Trooper Tropic Trooper used netview to scan target systems for shared resources. [21]
Zebrocy Zebrocy identifies network drives when they are added to victim systems. [13]

Mitigations

This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.

Detection

System and network discovery techniques normally occur throughout an operation as an adversary learns the environment. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities, such as Lateral Movement, based on the information obtained.

Normal, benign system and network events related to legitimate remote system discovery may be uncommon, depending on the environment and how they are used. Monitor processes and command-line arguments for actions that could be taken to gather system and network information. Remote access tools with built-in features may interact directly with the Windows API to gather information. Information may also be acquired through Windows system management tools such as Windows Management Instrumentation and PowerShell.

In cloud-based systems, native logging can be used to identify access to certain APIs and dashboards that may contain system information. Depending on how the environment is used, that data alone may not be sufficient due to benign use during normal operations.

References

  1. Symantec Security Response Attack Investigation Team. (2018, April 23). New Orangeworm attack group targets the healthcare sector in the U.S., Europe, and Asia. Retrieved May 8, 2018.
  2. Kaspersky Lab's Global Research & Analysis Team. (2018, February 20). A Slice of 2017 Sofacy Activity. Retrieved November 27, 2018.
  3. Symantec Security Response. (2016, September 6). Buckeye cyberespionage group shifts gaze from US to Hong Kong. Retrieved September 26, 2016.
  4. Computer Incident Response Center Luxembourg. (2013, March 29). Analysis of a PlugX variant. Retrieved November 5, 2018.
  5. Mercer, W. and Rascagneres, P. (2018, February 12). Olympic Destroyer Takes Aim At Winter Olympics. Retrieved March 14, 2019.
  6. US-CERT. (2018, March 16). Alert (TA18-074A): Russian Government Cyber Activity Targeting Energy and Other Critical Infrastructure Sectors. Retrieved June 6, 2018.
  7. US-CERT. (2017, October 20). Alert (TA17-293A): Advanced Persistent Threat Activity Targeting Energy and Other Critical Infrastructure Sectors. Retrieved November 2, 2017.
  8. Symantec Security Response. (2017, November 7). Sowbug: Cyber espionage group targets South American and Southeast Asian governments. Retrieved November 16, 2017.
  9. Mandiant. (n.d.). APT1 Exposing One of China’s Cyber Espionage Units. Retrieved July 18, 2016.
  10. Alintanahin, K. (2015). Operation Tropic Trooper: Relying on Tried-and-Tested Flaws to Infiltrate Secret Keepers. Retrieved June 14, 2019.
  11. Fraser, N., et al. (2019, August 7). Double DragonAPT41, a dual espionage and cyber crime operation APT41. Retrieved September 23, 2019.