Network Service Scanning

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Network Service Scanning
Technique
ID T1046
Tactic Discovery
Platform Windows Server 2003, Windows Server 2008, Windows Server 2012, Windows XP, Windows 7, Windows 8, Windows Server 2003 R2, Windows Server 2008 R2, Windows Server 2012 R2, Windows Vista, Windows 8.1, Windows 10
Permissions Required User, Administrator, SYSTEM
Data Sources Netflow/Enclave netflow, Network protocol analysis, Packet capture, Process command-line parameters, Process use of network

Adversaries may attempt to get a listing of services running on remote hosts, including those that may be vulnerable to remote software exploitation. Methods to acquire this information include port scans and vulnerability scans using tools that are brought onto a system.

Examples

  • FIN6 used publicly available tools (including Microsoft's built-in SQL querying tool, osql.exe) to map the internal network and conduct reconnaissance against Active Directory, Structured Query Language (SQL) servers, and NetBIOS.1
  • Suckfly the victim's internal network for hosts with ports 8080, 5900, and 40 open.2
  • Threat Group-3390 actors use the Hunter tool to conduct network service discovery for vulnerable systems.3
  • menuPass has used tcping.exe, similar to Ping, to probe port status on systems of interest.4
  • BlackEnergy has conducted port scans on a host.5
  • Cobalt Strike can perform port scans from an infected host.6
  • HDoor scans to identify open ports on the victim. 7
  • Remsec has a plugin that can perform ARP scanning as well as port scanning.8
  • XTunnel is capable of probing the network for open ports.9

Mitigation

Use network intrusion detection/prevention systems to detect and prevent remote service scans. Ensure that unnecessary ports and services are closed and proper network segmentation is followed to protect critical servers and devices.

Identify unnecessary system utilities or potentially malicious software that may be used to acquire information about services running on remote systems, 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 from legitimate remote service scanning may be uncommon, depending on the environment and how they are used. Legitimate open port and vulnerability scanning may be conducted within the environment and will need to be deconflicted with any detection capabilities developed. Network intrusion detection systems can also be used to identify scanning activity. Monitor for process use of the networks and inspect intra-network flows to detect port scans.

References