You seem fixated on MD-5, even though I've never mentioned a particular hash, so let's try SHA-1 its supposedly secure successor.
http://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html

February 18, 2005
...
Earlier this week, three Chinese cryptographers showed that SHA-1 is not collision-free. That is, they developed an algorithm for finding collisions faster than brute force.

Any crypto hash that results in less bits out than bits input will have collisions. That should be obvious. After all there is an infinite number of possible messages and only a finite set of possible hashes. Translation there is an infinite set of messages that will hash to a given value. Exploiting it however may be a PITA. But governments have time and cash to take on PITA projects.

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You seem fixated on MD-5, even though I've never mentioned a particular hash, so let's try SHA-1 its supposedly secure successor.
http://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html

February 18, 2005
...
Earlier this week, three Chinese cryptographers showed that SHA-1 is not collision-free. That is, they developed an algorithm for finding collisions faster than brute force.

Any crypto hash that results in less bits out than bits input will have collisions. That should be obvious. After all there is an infinite number of possible messages and only a finite set of possible hashes. Translation there is an infinite set of messages that will hash to a given value. Exploiting it however may be a PITA. But governments have time and cash to take on PITA projects.

Just to add the all important context from that (old) article:

They can find collisions in SHA-1 in 2^69 calculations, about 2,000 times faster than brute force. Right now, that is just on the far edge of feasibility with current technology. Two comparable massive computations illustrate that point.

In 1999, a group of cryptographers built a DES cracker. It was able to perform 2^56 DES operations in 56 hours. The machine cost $250K to build, although duplicates could be made in the $50K-$75K range. Extrapolating that machine using Moore's Law, a similar machine built today could perform 2^60 calculations in 56 hours, and 2^69 calculations in three and a quarter years. Or, a machine that cost $25M-$38M could do 2^69 calculations in the same 56 hours.


The git repository for the linux kernel code uses a hash function producing "160-bit numbers, which are quite big by normal standards - it is roughly equal to the number of atoms in the Earth".

See: The cracking of kernel.org


I thought the 'faster-than-brute-force' attack method for SHA had been improved recently, as opposed to the 2005 date on that article. However, that still translates into an impractically expensive attack, even for "Evil Government supercomputers", and even if they could also somehow sneak past the change/update logs and still have noone notice.

Perhaps git should indeed be updated to use SHA-512...? That's just a case of your preferred level of paranoia.


Aside: For my backups checks, 'incremental' backups use hash checks, whereas full snapshot backups run a direct binary comparison. But then, I'm unusually paranoid for backups and data transfer...

Keep searchin',
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

Wow!

As I predicted long ago that any significant security breach of a Linux server will make worldwide headline news... Well, here we have it!


Linux Community Websites Hacked

... a non-profit group created to help fuel the growth of Linux, has taken down LinuxFoundation.org, Linux.com and their subdomains for maintenance following the breach, which it believes to be connected to an attack on kernel.org in August.

‘Extreme caution’

“The Linux Foundation made this decision in the interest of extreme caution and security best practices,” the Foundation said in a statement on linux.com.

The Foundation said it was in the process of restoring services as quickly as possible, and advised users to regard passwords and SSH keys used on its sites as having been compromised. ...

... The recent attacks may actually mean positive publicity for Linux, according to Sophos security researcher Paul Ducklin.

“The ‘Linux is a nothing more than a hobby product’ naysayers will be compelled to admit that the operating system really is part of the Big Time. Why else would kernel.org be in the sights of cybercrooks?” he wrote on a Sophos blog. “And Linux itself will emerge almost entirely unscathed because if any dodgy changes are found in the codebase, there will be a public record of them getting rolled back and order restored.”


Linux and the Giant Breach

"Cause for concern? Yes, but there's no reason to believe that kernel sources were compromised; such a change would be easily detected with diff," ...

Security scares are so commonplace in the tech industry today that it's virtually impossible to keep track of them all. Security scares in the Linux world, however, are still rare enough as to cause at least a small collective gasp of consternation. ...

... "of course this is a serious concern but it's not the end of Linux by any means," agreed blogger Robert Pogson.

"I expect procedures on the servers will be tightened up to prevent/detect a recurrence," Pogson added. "Sometimes it takes a failure to provoke positive changes."

Meanwhile, "the ability of Linus to switch to GitHub running software that he wrote shows the tremendous adaptability of FLOSS," Pogson said.
'This Should Improve Confidence'

Barbara Hudson, a blogger on Slashdot who goes by "Tom" on the site, took a similar view.

"A developer's remote machine co-located on the same network was compromised, their password sniffed, and used to do some monkey business on the kernel servers," Hudson told Linux Girl. "In the end, it looks like no permanent damage was done, and that the existing people, procedures and infrastructure are robust enough to recover cleanly."

In fact, "this should improve, not reduce, confidence in the Linux development process," Hudson opined. ...


There's an awful lot of noise on various forums and comments lists to various media articles. There's quite a lot of gloating from Microsoft fan-boys who seem to be oblivious of the staggering gulf between the rarity of this sort of event in the Linux world as compared to other server systems...


This small event should show nicely the robust power of FLOSS and open honest peer review to quickly recover to be stronger yet.

IT is what we make it!
Martin


FLOSS: Free/Libre Open Source Software

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

Linux is 20 years old, so it is now full of holes, security wise.
as martin proved earlier.

Linux is 20 years old, so it is now full of holes, security wise.
as martin proved earlier.

ROTFLMAO!

Perhaps you need to read again what Ozzfan and myself have posted, and the outcome. Also note that your hero Microsoft looks to be making more money out of Linux systems than from it's own Windows!... (Android continues to be a gold mine for Microsoft... Really innovation? Or just good old fashioned extortion?)

The nature of FLOSS and open peer review is that any hole very publicly gets uncovered and fixed, quickly. The same mechanisms also ensure that very few holes ever see the light of day or last long enough to get exploited.

Please watch the news. We'll welcome any useful comments from you.

Regards,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

... so let's try SHA-1 its supposedly secure successor.
http://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html
[...]

Just to add the all important context from that (old) article:

They can find collisions in SHA-1 in 2^69 calculations, ...

... a machine that cost $25M-$38M could do 2^69 calculations in the same 56 hours.

... an impractically expensive attack, even for "Evil Government supercomputers", and even if they could also somehow sneak past the change/update logs and still have noone notice.

Perhaps git should indeed be updated to use SHA-512...? That's just a case of your preferred level of paranoia. ...

Then again, there is also this trick:

xkcd: Security


Keep searchin',
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

Linux is 20 years old, so it is now full of holes, security wise.
as martin proved earlier.

ROTFLMAO!

Perhaps you need to read again what Ozzfan and myself have posted, and the outcome. Also note that your hero Microsoft looks to be making more money out of Linux systems than from it's own Windows!... (Android continues to be a gold mine for Microsoft... Really innovation? Or just good old fashioned extortion?)

The nature of FLOSS and open peer review is that any hole very publicly gets uncovered and fixed, quickly. The same mechanisms also ensure that very few holes ever see the light of day or last long enough to get exploited.

Please watch the news. We'll welcome any useful comments from you.

Regards,
Martin

Microsoft looks to be making more money out of Linux systems than from it's own Windows mobile.

and that is old, since this is not referring WP7.

but why not to make money out of linux too.

The nature of FLOSS and open peer review is that any hole very publicly gets uncovered and fixed, quickly.Regards,
Martin

there was just a test how well people can find bugs and things from code, and even best professionals did very badly.

they just don´t find them.

The nature of FLOSS and open peer review is that any hole very publicly gets uncovered and fixed, quickly.

there was just a test how well people can find bugs and things from code, and even best professionals did very badly.

they just don´t find them.

Note in the world of FLOSS:

"given enough eyeballs, all bugs are shallow"


That notes how peer review (utilising "many eyeballs") is far more effective than closed and secretive 'proprietary' development where there are necessarily a very few bleary "eyeballs" working under business pressures and difficult time constraints...


Keep searchin',
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

That notes how peer review (utilising "many eyeballs") is far more effective than closed and secretive 'proprietary' development where there are necessarily a very few bleary "eyeballs" working under business pressures and difficult time constraints...

An open source project is just like a committee: A headless beast with legs running in different directions.

---

So thats why Linux is so stable. True it is headless but most of the coders seem to know good code when they see it and have little problem accepting what others have done or changing a few lines that make the code better. The big thing is that its not about the Ego or a paycheck to get things done

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In a rich man's house there is no place to spit but his face.
Diogenes Of Sinope

Some time after the host compromise, the story has been presented in detail at The 2011 Kernel Summit:

KS2011: Kernel.org report

One of the biggest events overshadowing the 2011 kernel summit was the compromise of kernel.org and its slow recovery, so it was fitting that kernel.org was the first topic to be discussed. A bit more information on what happened was on offer and future directions were considered. The future version of kernel.org will be rather more secure than its predecessors. ...

... Kernel.org also ended up supporting a bugzilla installation, patchwork, various wikis, the kerneloops.org site, and more. Running kernel.org had turned into a big, complex job.

On the morning of August 28, 2011, Peter discovered that his personal server had been compromised. As he dug into the situation, it became clear that kernel.org had been hit as well. The attack turns out to have been part of a widespread credential-stealing network that has been operating for some years now; it is clear that the site had been owned by this network for some time before it was discovered. What also seems to be clear is that this was not a targeted attack; kernel.org was just another on a long list of broken machines.

The attackers operated quietly...

... seemingly, were able to exploit ssh agent forwarding to move on to new machines. What they did not do was to mess with the data on kernel.org; after an extensive investigation, no data tampering has been found. Even so, kernel.org is coming back without all the old data; developers are asked to carefully review anything they care about before re-uploading it.

Kernel.org is being rebuilt from the beginning with a much greater separation of services; it will also be moving fully into the Linux Foundation. ... There will be additional staff to do the job properly, and no more volunteer administrators. Only full-time administrators will have root access to the systems involved...

John Hawley, the current full-time administrator, talked about the design of the new site. The old kernel.org had a single system, called "hera," that was at the center of everything. The new version will be much more distributed, with hera's functions split out to a number of separate boxes (some of which will be virtual machines). The site is currently being built on machines that had originally been delivered to the Linux Foundation for other purposes; he noted that the firewall box has 24 CPUs and 32GB of memory, which ought to be enough for the task. Currently only John has access to the new systems; until somebody else is hired, the community needs to cross its fingers against the possibility of bus-related accidents. ...


So... A story of an evolution into an overworked expanded hubris to then be attacked via an external privileged access via automated (root?) access... No data tampered with but all credentials must be considered compromised. From that, a complete reorganisation and rebuild of the site is being done, all very thoroughly.

Quite a story, and volunteer admins are as human as everyone else.


I for one have never trusted the convenience of ssh agent forwarding for precisely the threat of what compromised kernel.org... (I similarly do not trust VPNs... Such connections are strictly considered as 'untrusted'!)

IT is what we make it,
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)