Re: Unattended reboots (was Re: The clouds are not random enough)
Arshad Noor writes: >If you (or anyone on this forum) know of technology that allows the >application to gain access to the crypto-hardware after an unattended reboot >- but can prevent an attacker from gaining access to those keys after >compromising a legitimate ID on the machine - I'd welcome hearing about it. I talked to an auditor about this a while back, here's my summary of this: For auditing purposes the only thing that.s required for unattended restart is a mechanism to prevent an attacker from copying unprotected keying material from the machine. For example storing the key in a token plugged into the machine is generally considered sufficient because it gives you the ability to point to a physical security procedure that.s used to prevent the key (meaning the token that it.s held in) from being removed. This functions as an audit mechanism because it.ll be noticed if someone removes the token, which isn.t the case if someone copies a file containing the unprotected key from the machine. Hardware security modules (HSMs, a special-purpose crypto computing device capable of storing thousands of keys and performing encryption, signing, certificate management, and many other operations) are often used for this purpose, storing a single symmetric key in the HSM to meet audit requirements. If the HSM vendor has particularly good salespeople then they.ll sell the client at least two $20,000 HSMs (each storing a single key) for disaster recovery purposes. In other word's the target isn't necessarily what's good enough for security people, but what's good enough for the auditors, and the above was deemed good enough for the auditors. Peter. - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majord...@metzdowd.com
Re: Unattended reboots (was Re: The clouds are not random enough)
Hi, > If you (or anyone on this forum) know of technology that allows the > application to gain access to the crypto-hardware after an unattended > reboot - but can prevent an attacker from gaining access to those keys > after compromising a legitimate ID on the machine - I'd welcome hearing > about it. TIA. I (re?)invented a concept for that application, which can be applied in certain situations. I have started from the assumption that we are talking about something like an E-Business system that is hosted in a normal commercial environment with wired, routed networks. The attack-vector I wanted to secure against was stealing the machines. So in the scenario, an attacker would break into the building, steal the server, get out again, and would try to get access to the data afterwards. As long as the machine stays in place, it should be able to reboot unattendedly, as soon as it's somewhere else, it shouldn't be able to reboot unattendedly anymore. The concept is to have a secondary server (or several secondary servers) somewhere else, which has the necessary key available. It should be situated in a place where it is highly unlikely that it also gets stolen when the primary server gets stolen, and it has to be connected through a somewhat trusted routed network. Now the secondary server has configured the IP address of the primary server, and regularly tries to contact the primary server, every minute or something. (Or it uses a different method to detect when the primary server needs the key). The contact-tries are done over the routed network, and the routers must be somewhat secured, and the links in between also have to be trusted. When the secondary server succeeds the connection to the primary server, it authenticates the connection to the primary server (with a key that is stored in plaintext on the primary server, or perhaps generated from the hardware configuration). If the authentication succeeds, the secondary server sends the private key to the primary server, and the primary server can continue to boot normally. If an attacker steals the server, and connects it at a different place in the network, or somewhere else, then the secondary server will not be able to reach the IP address due to the routing, and won't be able to provide the key. So the attacker could only try to break in again, and trace back where the server is, where it comes from, ... Due to the connection originating from the secondary server and not from the primary server, you have to have both the server, and you have to be on the right place of the network. It's not perfect security, but I think it's a reasonable tradeoff for the given threats and the need for high-availability in those certain situations. Please let me know if you hear about any other interesting solutions too. Best regards, Philipp Gühring - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majord...@metzdowd.com
Re: Unattended reboots (was Re: The clouds are not random enough)
> If you (or anyone on this forum) know of technology that allows the > application to gain access to the crypto-hardware after an unattended > reboot - but can prevent an attacker from gaining access to those keys > after compromising a legitimate ID on the machine This is the conundrum of the of the the decade. The TPMs etc, tie a HDD to a server. This helps in cases where the HDDs are discarded w/o proper destruction of data or are stolen. If you have a problem of entire servers being stolen, than you have to worry about physical security. saqib http://kawphi.blogspot.com - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majord...@metzdowd.com
Re: Unattended reboots (was Re: The clouds are not random enough)
> All the HSMs I've worked with start their system daemons automatically; > but the applications using them must still authenticate themselves to > the HSM before keys can be used. How do the cards you've worked with > authenticate the application if no PINs are involved? Sorry, I wasn't clear enough. When I think PIN I think of a keypad and secure channel to the HSM. Not the name/password used by the application. For that, of course, you're right -- the application needs it. /r$ -- STSM, DataPower CTO WebSphere Appliance Architect http://www.ibm.com/software/integration/datapower/ - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majord...@metzdowd.com
Re: Unattended reboots (was Re: The clouds are not random enough)
Arshad Noor wrote: Almost every e-commerce site (that needs to be PCI-DSS compliant) I've worked with in the last few years, insists on having unattended reboots. Not only that but many will be multi-node High Availability cluster systems as well or will be horizontally scaled. This means that there are multiple machines needing access to the same key material. Or it means putting a crypto protocol terminator "on the front" - the down side of that is loosing end to end security. Even when the server is configured with a FIPS-certified HSM and the cryptographic keys are in secure storage with M of N controls for access to the keys, in order for the application to have access to the keys in the crypto hardware upon an unattended reboot, This is because availability of the service is actually more important to the business than "real" security. > the PINs to the hardware must be accessible to the application. If the application has automatic Or at least a broker for the application. access to the PINs, then so does an attacker who manages to gain entry to the machine. The way we have traditionally done that in Solaris for IKE is to write the passphrase/PIN in the clear to disk but rely on UNIX permissions to "protect" ie readable only to root or the user account the service runs as. P.S. As an aside, the solution we have settled on is to have the key- custodians enter their PINs to the crypto-hardware (even from remote locations, if needed, through secure channels). While it does not provide for unattended reboots, it does minimize the latency between reboots while ensuring that there is nothing persistent on the machine with PINs to the crypto-hardware. We recently added this ability for the IKE daemon on Solaris/OpenSolaris for the case when the private keys IKE uses are stored in a PKCS#11 keystore (HSM or TPM). However we don't expect this to be used in the case where unattended reboots or cluster failover be used. This is really no different to storing a root/host/service keytab on disk for Kerberos - yet that seems to be accepted practice even in organisations that by policy don't want passphrase/PIN on disk. -- Darren J Moffat - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majord...@metzdowd.com
Re: Unattended reboots (was Re: The clouds are not random enough)
Arshad Noor wrote: > to the keys, in order for the application to have access to the keys in > the crypto hardware upon an unattended reboot, the PINs to the hardware > must be accessible to the application. If the application has automatic > access to the PINs, then so does an attacker who manages to gain entry > to the machine. > If you (or anyone on this forum) know of technology that allows the > application to gain access to the crypto-hardware after an unattended > reboot - but can prevent an attacker from gaining access to those keys > after compromising a legitimate ID on the machine - I'd welcome hearing > about it. TIA. You could have a device that uses the keys only once for each time it is powered on, and see that the intended process uses it early in the boot process to answer the challenge of whatever it's authenticating to. This could be simulated in s/w using something such as BSD securelevel or having a different sudoers file for one part of the boot process. Then you're going to want only cold reboots, and if your device doesn't work when expected you'd wonder whether someone beat you to it. - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majord...@metzdowd.com
Re: Unattended reboots (was Re: The clouds are not random enough)
Richard Salz wrote: The cards that I know about work differently -- you configure them to allow unattended reboot, and then no PIN is involved. This is a little more secure, in that it requires a conscious decision to do this, as opposed to sticking the PIN somewhere on the filesystem. I'm not sure I'm following, Richard. All the HSMs I've worked with start their system daemons automatically; but the applications using them must still authenticate themselves to the HSM before keys can be used. How do the cards you've worked with authenticate the application if no PINs are involved? Arshad Noor StrongAuth, Inc. - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majord...@metzdowd.com
Re: Unattended reboots (was Re: The clouds are not random enough)
> in order for the application to have access to the keys in > the crypto hardware upon an unattended reboot, the PINs to the hardware > must be accessible to the application. The cards that I know about work differently -- you configure them to allow unattended reboot, and then no PIN is involved. This is a little more secure, in that it requires a conscious decision to do this, as opposed to sticking the PIN somewhere on the filesystem. /r$ -- STSM, DataPower CTO WebSphere Appliance Architect http://www.ibm.com/software/integration/datapower/ - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majord...@metzdowd.com
Unattended reboots (was Re: The clouds are not random enough)
Jerry Leichter wrote: How does a server, built on stock technology, keep secrets that it can use to authenticate with other servers after an unattended reboot? Without tamper-resistant hardware that controls access to keys, anything the software can get at at boot, an attacker who steals a copy of a backup, say - can also get at. I would be very interested in learning what conclusions you came to, Jerry. It is my experience that even *with* tamper-resistant hardware (TPM, HSM, smartcard), the threat of breach is very high if the server is configured for unattended reboots. Almost every e-commerce site (that needs to be PCI-DSS compliant) I've worked with in the last few years, insists on having unattended reboots. Even when the server is configured with a FIPS-certified HSM and the cryptographic keys are in secure storage with M of N controls for access to the keys, in order for the application to have access to the keys in the crypto hardware upon an unattended reboot, the PINs to the hardware must be accessible to the application. If the application has automatic access to the PINs, then so does an attacker who manages to gain entry to the machine. If you (or anyone on this forum) know of technology that allows the application to gain access to the crypto-hardware after an unattended reboot - but can prevent an attacker from gaining access to those keys after compromising a legitimate ID on the machine - I'd welcome hearing about it. TIA. Arshad Noor StrongAuth, Inc. P.S. As an aside, the solution we have settled on is to have the key- custodians enter their PINs to the crypto-hardware (even from remote locations, if needed, through secure channels). While it does not provide for unattended reboots, it does minimize the latency between reboots while ensuring that there is nothing persistent on the machine with PINs to the crypto-hardware. - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majord...@metzdowd.com
Re: The clouds are not random enough
On Sat, Aug 1, 2009 at 10:06 PM, Jerry Leichter wrote: >> Why Cloud Computing Needs More Chaos: >> >> http://www.forbes.com/2009/07/30/cloud-computing-security-technology-cio-network-cloud-computing.html >> >> [Moderator's note: ... the article is about a growing problem -- the >> lack of good quality random numbers in VMs provided by services like EC2 >> and the effect this has on security. --Perry] > > The problem is broader than this. A while back, I evaluated a technology > that did it best to solve a basically insoluble problem: How does a server, > built on stock technology, keep secrets that it can use to authenticate with > other servers after an unattended reboot? Without tamper-resistant hardware > that controls access to keys, anything the software can get at at boot, an > attacker who steals a copy of a backup, say - can also get at. So, the > trick is to use a variety of measurements of the hardware - amount of > memory, disk sizes, disk serial numbers, whatever you can think of that > varies from machine to machine and is not stored in a backup - and combines > them to produce a key that encrypts the important secrets. Since hardware > does need to be fixed or upgraded at times, a good implementation will use > some kind of "m unchanged out of n measurements" algorithm. Basically, this > is the kind of thing Microsoft uses to lock license keys to particular > instances of hardware. Yes, it can be broken - but you can make breaking it > a great deal of work. > > Virtualization changes all of this. Every copy of a virtual machine is will > be identical as far as most of these measurements are concerned. I'd imagine (I'm not particularly interested in licence enforcement, so I really am imagining), that the opposite was the problem: i.e. that the host could run you on any VM which might have wildly varying characteristics, depending on what the real machine underneath was, and what else you were sharing with. So, every time you see the measurements, they'll be different. - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majord...@metzdowd.com
Re: The clouds are not random enough
Why Cloud Computing Needs More Chaos: http://www.forbes.com/2009/07/30/cloud-computing-security-technology-cio-network-cloud-computing.html [Moderator's note: ... the article is about a growing problem -- the lack of good quality random numbers in VMs provided by services like EC2 and the effect this has on security. --Perry] The problem is broader than this. A while back, I evaluated a technology that did it best to solve a basically insoluble problem: How does a server, built on stock technology, keep secrets that it can use to authenticate with other servers after an unattended reboot? Without tamper-resistant hardware that controls access to keys, anything the software can get at at boot, an attacker who steals a copy of a backup, say - can also get at. So, the trick is to use a variety of measurements of the hardware - amount of memory, disk sizes, disk serial numbers, whatever you can think of that varies from machine to machine and is not stored in a backup - and combines them to produce a key that encrypts the important secrets. Since hardware does need to be fixed or upgraded at times, a good implementation will use some kind of "m unchanged out of n measurements" algorithm. Basically, this is the kind of thing Microsoft uses to lock license keys to particular instances of hardware. Yes, it can be broken - but you can make breaking it a great deal of work. Virtualization changes all of this. Every copy of a virtual machine is will be identical as far as most of these measurements are concerned. Conversely, if you try to let the physical level show through - e.g., use the disk serial number of the real disk on which a virtual disk lives - you disrupt some of the things VM's are trying to provide, lie easy transportability of instances from one hardware "home" to another. The last I heard about the technology I looked at, they didn't have any good solution for VM's (though I haven't kept up and don't know the current status). Ultimately, the only solution is for hypervisors to take on some security roles - passing along unforgeable ID's and random numbers from hardware and other resources that they have access to but do not export to the guest OS's. That doesn't *solve* the problem. It puts us back where we were before the virtualization craze: Needing to write a secure OS and various secure services. However, since hypervisors are much smaller and *much* more limited in operation than full OS's, so the problems may be correspondingly easier to solve. -- Jerry - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majord...@metzdowd.com
The clouds are not random enough
Why Cloud Computing Needs More Chaos: http://www.forbes.com/2009/07/30/cloud-computing-security-technology-cio-network-cloud-computing.html [Moderator's note: It is not supposed to be the moderator's job to read a link and then summarize for the readers it is interesting to click on. In the future, posters should provide at least a few sentences explaining why a link is of interest or I'm going to simply stop forwarding them. In the current instance, the article is about a growing problem -- the lack of good quality random numbers in VMs provided by services like EC2 and the effect this has on security. --Perry] - The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majord...@metzdowd.com
