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This page should collect information about security topics.


In most programs, only parts of a program are directly working with "outside" data (from a file or network), so to avoid security problems, the developers are doing code reviews about that parts which (hopefully) will eliminate most security problems.

Ethereal is a bit different here, as almost the complete code will work with data from the "outside" (whether it's from a live capture or loaded from a file), so a code review on the relevant parts would be a code review of most if not all of the complete Ethereal code which would be a huge effort, and not all problems might be found after all. This makes Ethereal more vulnerable to attacks than most other programs.

Ethereal is implemented in ANSI C which is vulnerable to security problems like buffer overflows (compared to more securely designed languages like Java or C#). ANSI C is used for several reasons; the main reason is performance, as Ethereal is often used to work with huge amounts of data, and another reason is that implementations of other languages might not be as commonly available on all the platforms Ethereal support. Some of this might be solved, at least for some dissectors, by having higher-level languages used to describe protocols, with translators to C for those languages; if the translators have been reviewed to make sure they generate "safe" code, and the code they call has been reviewed to make sure it's safe, then dissectors written in those higher-level languages will be safe. For example, some dissectors for protocols using ASN.1 are generated from an ASN.1 description of the protocol.

A further security problem is that the Ethereal development process includes patches from many different developers (with different levels of programming skills) all around the world, and only a few developers are doing the job of reviewing the patches before they are checked in the main source tree.

Conclusion: The current development model won't change for several reasons, so if there are concerns about the mentioned security problems, different approaches avoiding the drawbacks of these problems should be taken.

The best way might be to run Ethereal in a user account which can't do any real harm. As on some platforms live capturing from the network needs administration privileges, additional steps have to be taken; see below.


The WinPcap (NPF) driver is loaded by Ethereal when it starts to capture live data.

This loading requires administrator privileges. Once the driver is loaded, every local user can capture from it until it's stopped again.

To be secure (at least in a way), it is recommended that the administrator should always running in a user account, and only start processes that really need the administrator privileges.

So using Ethereal running in a user account could look like:

Start the NPF driver:

runas /u:administrator "net start npf"

Start Ethereal and work with it, including capturing, until the specific job is finished.

Stop the NPF driver again:

runas /u:administrator "net stop npf"

This way, it's a lot more secure than running with the administrator account. However, while doing this, any local user can also capture from the network. This might not be desireable, but this can't be currently circumvented. Please note that this is not a limitation of the Ethereal implementation, but of the underlying WinPcap driver; see [ this note in the WinPcap FAQ].