Perimeter
2/3/2012
02:19 PM
John H. Sawyer
John H. Sawyer
Commentary
50%
50%

Passive Network Fingerprinting; p0f Gets Fresh Rewrite

Passive network analysis can reveal OS, service, and even vulnerabilities -- just by sniffing the network

In the network security world, nmap is the king for fingerprinting systems and services over the network. It can help identify the operating system (OS), type, and version of a network service, and vulnerabilities that might be present. The problem with nmap is that it generates a lot of "noise" when it performs those activities because it has to send out packets to the system in question to learn more about it. Nmap is an example of an active fingerprinting tool.

There are less noisy alternatives to nmap that fall into the passive fingerprinting category. Instead of actively sending packets to a host and service, they passively analyze network traffic to identify unique characteristics for particular operating systems, client applications, and network services. Their strength is based on the breadth of their signature database, which is not always great. To date, the majority of free and open-source passive fingerprinting tools have focused on OS fingerprinting

Passive fingerprinting can go way beyond just identifying the operating system. Web and mail servers often give up more information than necessary when communicating with clients, and in general, as long as that traffic is unique and can be sniffed, a fingerprint can be created to identify it. The same goes for Web browsers, email clients, and any other application that communicates over the network. Often their version numbers are passed as part of their communications with servers. Tie that version information with a vulnerability database and vulnerable systems can start being identified without ever interacting with the system.

To date, PRADS is the one of the few open-source tools I've found that currently includes fingerprinting additional things like services; however, Michal Zalewski announced on Jan. 10 the availability of p0f v3, which includes the ability to fingerprint TCP services. This is the first release in about six years and is a complete rewrite. This new version currently supports HTTP response and request signatures, but additional protocols are expected to be added in the future.

The obvious difficulty with passive fingerprinting is the need to sniff the traffic, but if you're just monitoring traffic between yourself and another system, that's not an issue. In larger environments, you'll want to leverage a mirror port on a network switch or a network tap in order to see as much traffic as possible. The cool thing about p0f is that it can help find NAT devices in large environments where you might have users plugging in wireless routers.

There's a lot of value and fun that can be had through passive fingerprinting. I'll be discussing it more in the future as I start working on a project specific to mobile devices and application fingerprinting. For a quick preview and review on passive fingerprinting, check out my FireTalk, "Passive Aggressive Pwnage," at ShmooCon 2012.

John Sawyer is a Senior Security Analyst with InGuardians. The views and opinions expressed in this blog are his own and do not represent the views and opinions of his employer. He can be reached at johnhsawyer@gmail.com and found on Twitter @johnhsawyer.

Comment  | 
Print  | 
More Insights
Register for Dark Reading Newsletters
White Papers
Cartoon
Current Issue
Dark Reading December Tech Digest
Experts weigh in on the pros and cons of end-user security training.
Flash Poll
Title Partner’s Role in Perimeter Security
Title Partner’s Role in Perimeter Security
Considering how prevalent third-party attacks are, we need to ask hard questions about how partners and suppliers are safeguarding systems and data.
Video
Slideshows
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2014-6477
Published: 2014-11-23
Unspecified vulnerability in the JPublisher component in Oracle Database Server 11.1.0.7, 11.2.0.3, 11.2.0.4, 12.1.0.1, and 12.1.0.2 allows remote authenticated users to affect confidentiality via unknown vectors, a different vulnerability than CVE-2014-4290, CVE-2014-4291, CVE-2014-4292, CVE-2014-4...

CVE-2014-4807
Published: 2014-11-22
Sterling Order Management in IBM Sterling Selling and Fulfillment Suite 9.3.0 before FP8 allows remote authenticated users to cause a denial of service (CPU consumption) via a '\0' character.

CVE-2014-6183
Published: 2014-11-22
IBM Security Network Protection 5.1 before 5.1.0.0 FP13, 5.1.1 before 5.1.1.0 FP8, 5.1.2 before 5.1.2.0 FP9, 5.1.2.1 before FP5, 5.2 before 5.2.0.0 FP5, and 5.3 before 5.3.0.0 FP1 on XGS devices allows remote authenticated users to execute arbitrary commands via unspecified vectors.

CVE-2014-8626
Published: 2014-11-22
Stack-based buffer overflow in the date_from_ISO8601 function in ext/xmlrpc/libxmlrpc/xmlrpc.c in PHP before 5.2.7 allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code by including a timezone field in a date, leading to improper XML-RPC encoding...

CVE-2014-8710
Published: 2014-11-22
The decompress_sigcomp_message function in epan/sigcomp-udvm.c in the SigComp UDVM dissector in Wireshark 1.10.x before 1.10.11 allows remote attackers to cause a denial of service (buffer over-read and application crash) via a crafted packet.

Best of the Web
Dark Reading Radio
Archived Dark Reading Radio
Now that the holiday season is about to begin both online and in stores, will this be yet another season of nonstop gifting to cybercriminals?