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Simple Network Management Protocol (SNMP)

  • Baed on UDP - Can be suspectable for IP spoofing and replay
  • 1,2,2c versions are plain text
  • Week auth and default community strings (public, default)

Devices often support configuration file read and write through private SNMP community string access. Hence having access to private string means router configuration can be altered.

Configuration Files

snmp.conf
snmpd.conf
snmp-config.xml

SNMP - Management Information Base (MBI)

Tree database related to network management. http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?topic=/com.ibm.aix.progcomm/doc/progcomc/mib.htm

commuity strings - public / private / manager / ...

Scanning

nmap -sU --open -p 161 <ip> --open
Scan one community string for multiple IPs
onesixtyone -c community.txt -i ips.txt

Probe MBI

snmpwalk -c public -v1 <ip> 1.3.6.1.2.1.25.4.2.1.2
 • 1.3.6.1.2.1.25.1.6.0 System Processes
 • 1.3.6.1.2.1.25.4.2.1.2 Running Programs
 • 1.3.6.1.2.1.25.4.2.1.4 Processes Path
 • 1.3.6.1.2.1.25.2.3.1.4 Storage Units
 • 1.3.6.1.2.1.25.6.3.1.2 Software Name
 • 1.3.6.1.4.1.77.1.2.25 User Accounts
 • 1.3.6.1.2.1.6.13.1.3  TCP Local Ports

Default community strings

public
private
cisco
  cable-docsis
  ILMI

Important properties

Windows NT
.1.3.6.1.2.1.1.5 Hostnames
.1.3.6.1.4.1.77.1.4.2 Domain Name
.1.3.6.1.4.1.77.1.2.25 Usernames
.1.3.6.1.4.1.77.1.2.3.1.1 Running Services
.1.3.6.1.4.1.77.1.2.27 Share Information

Tools

snmpenum

perl snmpenum.pl 192.168.38.200 public windows.txt

snmpwalk

snmpwalk -c public 192.168.38.200 -v 1
  • OpUtils
  • SolarWinds
  • SNScan
  • SNMP Scanner
  • NS Auditor
  • snmpcheck
  • onesixtyone
    • Scan one community string for multiple IPs