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File smb-check-vulns

Script types: hostrule
Categories: intrusive, exploit, dos, vuln
Download: http://nmap.org/svn/scripts/smb-check-vulns.nse

User Summary

Checks for vulnerabilities:

  • MS08-067, a Windows RPC vulnerability
  • Conficker, an infection by the Conficker worm
  • Unnamed regsvc DoS, a denial-of-service vulnerability I accidentally found in Windows 2000
  • SMBv2 exploit (CVE-2009-3103, Microsoft Security Advisory 975497)
  • MS06-025, a Windows Ras RPC service vulnerability
  • MS07-029, a Windows Dns Server RPC service vulnerability

WARNING: These checks are dangerous, and are very likely to bring down a server. These should not be run in a production environment unless you (and, more importantly, the business) understand the risks!

As a system administrator, performing these kinds of checks is crucial, because a lot more damage can be done by a worm or a hacker using this vulnerability than by a scanner. Penetration testers, on the other hand, might not want to use this script -- crashing services is not generally a good way of sneaking through a network.

If you set the script parameter unsafe, then scripts will run that are almost (or totally) guaranteed to crash a vulnerable system; do NOT specify unsafe in a production environment! And that isn't to say that non-unsafe scripts will not crash a system, they're just less likely to.

If you set the script parameter safe, then script will run that rarely or never crash a vulnerable system. No promises, though.

MS08-067. Checks if a host is vulnerable to MS08-067, a Windows RPC vulnerability that can allow remote code execution. Checking for MS08-067 is very dangerous, as the check is likely to crash systems. On a fairly wide scan conducted by Brandon Enright, we determined that on average, a vulnerable system is more likely to crash than to survive the check. Out of 82 vulnerable systems, 52 crashed. At the same time, MS08-067 is extremely critical to fix. Metasploit has a working and stable exploit for it, and any system vulnerable can very easily be compromised. Conficker. Checks if a host is infected with a known Conficker strain. This check is based on the simple conficker scanner found on this page: http://iv.cs.uni-bonn.de/wg/cs/applications/containing-conficker. Thanks to the folks who wrote that scanner!

regsvc DoS. Checks if a host is vulnerable to a crash in regsvc, caused by a null pointer dereference. I inadvertently discovered this crash while working on smb-enum-sessions, and discovered that it was repeatable. It's been reported to Microsoft (case #MSRC8742).

This check WILL crash the service, if it's vulnerable, and requires a guest account or higher to work. It is considered unsafe.

SMBv2 DoS. Performs a denial-of-service against the vulnerability disclosed in CVE-2009-3103. Checks if the server went offline. This works against Windows Vista and some versions of Windows 7, and causes a bluescreen if successful. The proof-of-concept code at http://seclists.org/fulldisclosure/2009/Sep/39 was used, with one small change.

MS06-025. Vulnerability targets the RasRpcSumbitRequest() RPC method which is a part of RASRPC interface that serves as a RPC service for configuring and getting information from the Remote Access and Routing service. RASRPC can be accessed using either "\ROUTER" SMB pipe or the "\SRVSVC" SMB pipe (usually on Windows XP machines). This is in RPC world known as "ncan_np" RPC transport. RasRpcSumbitRequest() method is a generic method which provides different functionalities according to the RequestBuffer structure and particularly the RegType field within that structure. RegType field is of enum ReqTypes type. This enum type lists all the different available operation that can be performed using the RasRpcSubmitRequest() RPC method. The one particular operation that this vuln targets is the REQTYPE_GETDEVCONFIG request to get device information on the RRAS.

MS07-029. Vulnerability targets the R_DnssrvQuery() and R_DnssrvQuery2() RPC method which is a part of DNS Server RPC interface that serves as a RPC service for configuring and getting information from the DNS Server service. DNS Server RPC service can be accessed using "\dnsserver" SMB named pipe. The vulnerability is triggered when a long string is send as the "zone" parameter which causes the buffer overflow which crashes the service.

(Note: if you have other SMB/MSRPC vulnerability checks you'd like to see added, and you can show me a tool with a license that is compatible with Nmap's, post a request on the nmap-dev mailing list and I'll add it to my list [Ron Bowes].)

Script Arguments


If set, this script will only run checks that are known (or at least suspected) to be safe.


If set, this script will run checks that, if the system isn't patched, are basically guaranteed to crash something. Remember that non-unsafe checks aren't necessarily safe either)

randomseed, smbbasic, smbport, smbsign

See the documentation for the smb library.

smbdomain, smbhash, smbnoguest, smbpassword, smbtype, smbusername

See the documentation for the smbauth library.

Example Usage

nmap --script smb-check-vulns.nse -p445 <host>
sudo nmap -sU -sS --script smb-check-vulns.nse -p U:137,T:139 <host>

Script Output

Host script results:
| smb-check-vulns:
|   Conficker: Likely CLEAN
|   regsvc DoS: regsvc DoS: NOT VULNERABLE
|   SMBv2 DoS (CVE-2009-3103): NOT VULNERABLE
|   MS06-025: NO SERVICE (the Ras RPC service is inactive)
|_  MS07-029: NO SERVICE (the Dns Server RPC service is inactive)


Author: Ron Bowes

License: Same as Nmap--See http://nmap.org/book/man-legal.html

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