This wiki has been migrated to https://gitlab.com/wireshark/wireshark/-/wikis/home and is now deprecated. Please use that site instead.
Differences between revisions 2 and 12 (spanning 10 versions)
Revision 2 as of 2005-02-08 20:21:41
Size: 2893
Editor: UlfLamping
Comment: if you need admin privs to start a driver, you'll need the same privs to stop it
Revision 12 as of 2006-01-22 14:58:29
Size: 5445
Editor: UlfLamping
Comment: fix link
Deletions are marked like this. Additions are marked like this.
Line 3: Line 3:
This page should collect information about security topics. This page collects information about the secure usage of Ethereal.
Line 5: Line 5:
== General == [[TableOfContents]]
Line 7: Line 7:
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 developer's are doing code reviews about that parts which (hopefully) will eliminate most security problems. = Introduction =
Line 9: Line 9:
Ethereal is a bit different here, as almost the complete code will work with data from the "outside" (being it live captured or loaded from a file) making a code review on the relevant parts would be a code review of the complete Ethereal code which would be a '''huge''' effort, and not all problems might be found after all. This is making Ethereal more vulnerable to attacks than most other programs. In the recent months (years?), Ethereal was often mentioned in security bulletins about having several security related bugs fixed. This is caused by code reviews of individuals and interested parties and by the effort of the Ethereal team to automatically find bugs. It is expected that this will continue - at least in the near future.
Line 11: Line 11:
Ethereal is implemented in ANSI C which is vulnerable to security problems like buffer overflows (compared to more secure designed languages like JAVA or C#). ANSI C is used for several reasons, the main reason is perfomance, as Ethereal is often used to work with huge amounts of data. While there is currently no known exploit out there to attack Ethereal, this may change one day ...
Line 13: Line 13:
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 doing the job of reviewing the patches before they are checked in the main source tree. Because of this, special care should be taken to avoid security related problems while running Ethereal or at least to reduce the possible impact.
Line 15: Line 15:
'''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. Wether this is a problem for yourself will depend on the situation: A small !SoHo network will probably be less critical compared to a companies 24/7 mission critical web server.
Line 17: Line 17:
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, just see below. It's not the intention of this page to discuss the usage of Ethereal regarded by certain persons as being "insecure", because you can see network data like transported passwords. BTW: Security through obscurity just don't work.
Line 19: Line 19:
== Windows == = Why is Ethereal different? =
Line 21: Line 21:
The WinPcap (NPF) driver is loaded by Ethereal when it starts to capture live data. In most programs, small sections of code work directly with "outside" data (e.g. from a file or network). By focusing on these small sections during code reviews, developers can eliminate most security problems.
Line 23: Line 23:
This loading requires administrator privileges. Once the driver is loaded, every local user can capture from it until it's stopped again. Ethereal is different. The vast majority of its code base deals directly with data from the "outside", so a code review on the relevant parts would cover most if not all of the complete Ethereal code. Running "wc -l epan/dissectors/*.[ch]" returns about 1,000,000 lines of code that's expected to handle fresh-off-the-wire data! Auditing all of this would be a '''huge''' effort, and may not guarantee success.
Line 25: Line 25:
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. 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. Another reason is that implementations of other languages might not be as commonly available on all the platforms Ethereal supports.
Line 27: Line 27:
So using Ethereal running in a user account could look like: To make things worse, the Ethereal development is done in an "experimental character" as new protocols are added all the time and existing ones are largely improved, the main reason that Ethereal has gained such a wide support of protocols. The developers providing code to Ethereal (literally hundreds) have very divergent programming experience, from advanced networking specialists to novice programmers, making it more likely that new bugs get in.
Line 29: Line 29:
Start the NPF driver: As a result, Ethereal is more vulnerable to attacks than most other programs.
Line 31: Line 31:
{{{runas /u:administrator "net start npf"}}} = Which actions are critical? =
Line 33: Line 33:
Start Ethereal and work with it, including capturing, until the specific job is finished. Having a bug in the GUI code can be quite annoying, e.g. a crash while printing a capture file. However, these bugs are usually not security related as they cannot be triggered from the outside.
Line 35: Line 35:
Stop the NPF driver again: The most critical action is analyzing packets when they are read in. The following actions will call into the myriad lines of dissector code with data coming from the "outside":
Line 37: Line 37:
{{{runas /u:administrator "net stop npf"}}}  * Open a capture file
 * If "Update list of packets in real time" is used while capturing
 * if "Update list of packets in real time" is ''not'' used after capture stops
Line 39: Line 41:
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. = Administrator/root account usually not required! =

Many Ethereal users think that Ethereal requires a Administrator/root account to work with.

That's not a good idea, as using a root account makes any exploit far more dangerous: a successful exploit will have immediate control of the whole system, compromising it completely.

First of all, most Ethereal functions can always be used with a (probably very limited) user account. Especially the protocol dissectors which are showing most of the security related bugs doesn't need a root account!

Only capturing (and gathering capture interface information) may require a root account, but even that can usually be "circumvented", see ["CaptureSetup/CapturePrivileges"] for details how to do so.

= Protect Yourself! =

There are some things you can do:

 * Always update to the latest Ethereal version available as bugs are fixed often. You can join the announce mailing list to stay informed about new versions.
 * Don't run Ethereal as root/Administrator! See ["CaptureSetup/CapturePrivileges"] for details how to do so.
 * Analyze capture files in an uncritical environment. You may create a special (limited) user account or even use a dedicated machine for this task.
 * Use a small capture tool which is less likely affected by security bugs, e.g.: tcpdump (upcoming: dumpcap) and transfer the capture file to the uncritical environment mentioned above

= Help is on the way! =

The Ethereal developers agree that the current situation isn't actually satisfying.

Current effort is spend in several ways to improve Ethereal in that regard:

 * Automated tests uncovers previously unknown bugs
 * code reviews take place
 * potential unsecure functions are removed from the code
 * privilege seperation is being implemented (running the capture code in it's own task)
 * ... and many other things

You'll find more information about that effort at the ["Development/Security"] page.

As it's a lot of effort involved in the above tasks, it's unpredictable when they'll be finished (if ever).

Security

This page collects information about the secure usage of Ethereal.

TableOfContents

Introduction

In the recent months (years?), Ethereal was often mentioned in security bulletins about having several security related bugs fixed. This is caused by code reviews of individuals and interested parties and by the effort of the Ethereal team to automatically find bugs. It is expected that this will continue - at least in the near future.

While there is currently no known exploit out there to attack Ethereal, this may change one day ...

Because of this, special care should be taken to avoid security related problems while running Ethereal or at least to reduce the possible impact.

Wether this is a problem for yourself will depend on the situation: A small SoHo network will probably be less critical compared to a companies 24/7 mission critical web server.

It's not the intention of this page to discuss the usage of Ethereal regarded by certain persons as being "insecure", because you can see network data like transported passwords. BTW: Security through obscurity just don't work.

Why is Ethereal different?

In most programs, small sections of code work directly with "outside" data (e.g. from a file or network). By focusing on these small sections during code reviews, developers can eliminate most security problems.

Ethereal is different. The vast majority of its code base deals directly with data from the "outside", so a code review on the relevant parts would cover most if not all of the complete Ethereal code. Running "wc -l epan/dissectors/*.[ch]" returns about 1,000,000 lines of code that's expected to handle fresh-off-the-wire data! Auditing all of this would be a huge effort, and may not guarantee success.

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. Another reason is that implementations of other languages might not be as commonly available on all the platforms Ethereal supports.

To make things worse, the Ethereal development is done in an "experimental character" as new protocols are added all the time and existing ones are largely improved, the main reason that Ethereal has gained such a wide support of protocols. The developers providing code to Ethereal (literally hundreds) have very divergent programming experience, from advanced networking specialists to novice programmers, making it more likely that new bugs get in.

As a result, Ethereal is more vulnerable to attacks than most other programs.

Which actions are critical?

Having a bug in the GUI code can be quite annoying, e.g. a crash while printing a capture file. However, these bugs are usually not security related as they cannot be triggered from the outside.

The most critical action is analyzing packets when they are read in. The following actions will call into the myriad lines of dissector code with data coming from the "outside":

  • Open a capture file
  • If "Update list of packets in real time" is used while capturing
  • if "Update list of packets in real time" is not used after capture stops

Administrator/root account usually not required!

Many Ethereal users think that Ethereal requires a Administrator/root account to work with.

That's not a good idea, as using a root account makes any exploit far more dangerous: a successful exploit will have immediate control of the whole system, compromising it completely.

First of all, most Ethereal functions can always be used with a (probably very limited) user account. Especially the protocol dissectors which are showing most of the security related bugs doesn't need a root account!

Only capturing (and gathering capture interface information) may require a root account, but even that can usually be "circumvented", see ["CaptureSetup/CapturePrivileges"] for details how to do so.

Protect Yourself!

There are some things you can do:

  • Always update to the latest Ethereal version available as bugs are fixed often. You can join the announce mailing list to stay informed about new versions.
  • Don't run Ethereal as root/Administrator! See ["CaptureSetup/CapturePrivileges"] for details how to do so.

  • Analyze capture files in an uncritical environment. You may create a special (limited) user account or even use a dedicated machine for this task.
  • Use a small capture tool which is less likely affected by security bugs, e.g.: tcpdump (upcoming: dumpcap) and transfer the capture file to the uncritical environment mentioned above

Help is on the way!

The Ethereal developers agree that the current situation isn't actually satisfying.

Current effort is spend in several ways to improve Ethereal in that regard:

  • Automated tests uncovers previously unknown bugs
  • code reviews take place
  • potential unsecure functions are removed from the code
  • privilege seperation is being implemented (running the capture code in it's own task)
  • ... and many other things

You'll find more information about that effort at the ["Development/Security"] page.

As it's a lot of effort involved in the above tasks, it's unpredictable when they'll be finished (if ever).

Security (last edited 2015-08-22 15:51:05 by RuelBorais)