Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

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 [email protected] and found on Twitter @johnhsawyer.

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Why Cyber-Risk Is a C-Suite Issue
Marc Wilczek, Digital Strategist & CIO Advisor,  11/12/2019
Unreasonable Security Best Practices vs. Good Risk Management
Jack Freund, Director, Risk Science at RiskLens,  11/13/2019
Breaches Are Inevitable, So Embrace the Chaos
Ariel Zeitlin, Chief Technology Officer & Co-Founder, Guardicore,  11/13/2019
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Current Issue
Navigating the Deluge of Security Data
In this Tech Digest, Dark Reading shares the experiences of some top security practitioners as they navigate volumes of security data. We examine some examples of how enterprises can cull this data to find the clues they need.
Flash Poll
Rethinking Enterprise Data Defense
Rethinking Enterprise Data Defense
Frustrated with recurring intrusions and breaches, cybersecurity professionals are questioning some of the industrys conventional wisdom. Heres a look at what theyre thinking about.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2019-19010
PUBLISHED: 2019-11-16
Eval injection in the Math plugin of Limnoria (before 2019.11.09) and Supybot (through 2018-05-09) allows remote unprivileged attackers to disclose information or possibly have unspecified other impact via the calc and icalc IRC commands.
CVE-2019-16761
PUBLISHED: 2019-11-15
A specially crafted Bitcoin script can cause a discrepancy between the specified SLP consensus rules and the validation result of the [email protected] npm package. An attacker could create a specially crafted Bitcoin script in order to cause a hard-fork from the SLP consensus. All versions >1.0...
CVE-2019-16762
PUBLISHED: 2019-11-15
A specially crafted Bitcoin script can cause a discrepancy between the specified SLP consensus rules and the validation result of the slpjs npm package. An attacker could create a specially crafted Bitcoin script in order to cause a hard-fork from the SLP consensus. Affected users can upgrade to any...
CVE-2019-13581
PUBLISHED: 2019-11-15
An issue was discovered in Marvell 88W8688 Wi-Fi firmware before version p52, as used on Tesla Model S/X vehicles manufactured before March 2018, via the Parrot Faurecia Automotive FC6050W module. A heap-based buffer overflow allows remote attackers to cause a denial of service or execute arbitrary ...
CVE-2019-13582
PUBLISHED: 2019-11-15
An issue was discovered in Marvell 88W8688 Wi-Fi firmware before version p52, as used on Tesla Model S/X vehicles manufactured before March 2018, via the Parrot Faurecia Automotive FC6050W module. A stack overflow could lead to denial of service or arbitrary code execution.