Network Share Discovery

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Network Share Discovery
Technique
ID T1135
Tactic Discovery
Platform macOS, Windows
Permissions Required User
Data Sources Process Monitoring, Process command-line parameters, Network protocol analysis, Process use of network

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.12

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.

Examples

  • Dragonfly identified and browsed file servers on the victim network, viewing files pertaining to ICS or Supervisory Control and Data Acquisition (SCADA) systems.3
  • Sowbug listed remote shared drives that were accessible from a victim.4
  • Cobalt Strike can query shared drives on the local system.5
  • MURKYTOP has the capability to retrieve information about shares on remote hosts.6
  • 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.7
  • OSInfo discovers shares on the network 8
  • Pupy can list local and remote shared drives and folders over SMB.9

Mitigation

Identify unnecessary system utilities or potentially malicious software that may be used to acquire network share information, and audit and/or block them by using whitelisting10 tools, like AppLocker,1112 or Software Restriction Policies13 where appropriate.14

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.

References