Time to end the war on the network

Edward SnowdenWhen Edward Snowden disclosed the NSA’s activities, many people came to realize that network systems can be misused, even though this was always the case.  People just realized what was possible.  What happened next was a concerted effort to protect protect data from what has become known as “pervasive surveillance”.  This included development of a new version of HTTP that is always encrypted and an easy way to get certificates.

However, when end nodes hide everything from the network, not only can the network not be used by the bad guys, but it can no longer be used by the good guys to either authorize appropriate communications or identify attacks.  A example is spam.  Your mail server sits in front of you and can reject messages when they contain malware or are just garbage.  It does that by examining both the source of the message and the message itself.  Similarly, anyone who has read my writing about Things knows that the network needs just a little bit of information from the device in order to stop unwanted communications.

I have written an Internet Draft that begins to establish a framework for when and how information should be shared, with the idea being that information should be carefully shared with a purpose, understanding that there are risks involved in doing so.  The attacks on Twitter and on krebsonsecurity.com are preventable, but it requires us to recognize that end nodes are not infallible, and they never will be.  Neither, by the way, are network devices.  So long as all of these systems are designed and built by humans, that will be the case.  Each can help each other in good measure to protect the system as a whole.


Photo of Edward Swowden By Laura Poitras / Praxis Films, CC BY 3.0

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iPhone TouchID doesn’t protect you from the government

FingerprintIt’s a common belief that Apple has gone to extraordinary lengths to protect individuals’ privacy through mechanisms such as Touch ID, but what are its limits?  Today Forbes reported that a U.S. attorney was able to get a warrant for the fingerprints of everyone at a particular residence for the express purpose of unlocking iPhones.

Putting aside the shocking breadth of the warrant, suppose you want to resist granting access to an iPhone.  It is not that hard for someone to force your finger onto a phone.  It is quite a different matter for someone to force a password out of your head.  Apple has gone to some lengths to limit certain forms of attack.  For instance, the Touch ID generally will not authenticate a severed finger, nor will it authenticate a fingerprint copy.  Also, Apple doesn’t actually store fingerprint images, but rather hashes of the information used to collect fingerprints.  Note that if the hashing method is known, then the hash itself is sensitive.

For those who care, the question is what length someone is likely to go to gain access to a phone.  Were someone holding a gun to my head and demanding access to my phone, unless it meant harming my family, I’d probably give them the information they wanted.  Short of that, however, I might resist, at least long enough to get to have my day in court.  If that would be your approach, then you might want to skip Touch ID, lest someone simply gets rough with you to get your fingerprint.  The problem is that Touch ID cannot currently be required  in combination with a pass code on iPhones and iPads.  Either suffices.  And this goes against the a basic concept of two-factor authentication.  Combine something you have, like a fingerprint, with something you know, like a pass code.

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Let’s not blame Yahoo! for a difficult policy problem

Yahoo!Many in the tech community are upset over reports from The New York Times and others that Yahoo! responded to an order issued by the Foreign Intelligence Surveillance Act Court (FISC) to search across their entire account base a specific “signatures” of people believed to be terrorists.

It is not clear what capabilities Yahoo! already has, but it would not be unreasonable to expect them to have the ability to scan incoming messages for spam and malware, for instance.  What’s more, we are all the better for this sort of capability.  Consider that around 85% of all email is spam, a small amount of which contains malware, and Yahoo! users don’t see most of that.  Much of that can be rejected without Yahoo! having to look at the content by just examining the source IP address of the device attempting to send Yahoo! mail, but in all likelihood they do look at some, as many systems do.  In fact one of the most popular open source systems in the early days known as SpamAssassin did just this.  The challenge from a technical perspective is to implement such a mechanism without the mechanism itself having a large target surface.

If the government asking for certain messages sounds creepy, we have to ask what a signature is.  A signature normally refers to characteristics of a communication that would either identify its source or that it has some quality.  For instance, viruses all have signatures.  In this case, what is claimed is that terrorists communicated in a certain way such that they could be identified.  According to The Times, the government demonstrated probably cause that this was true, and that the signature was “highly unique”*.  That is, the signature likely matches very few actual messages that the government would see, although we don’t know how small that number really is.  Yahoo! has denied having a capability to scan across all messages in their system, but beyond that not enough is public to know what they would have done.  It may well not have been reasonable to search specific accounts because one can easily create an account, and the terrorists may have many.  The government publicly revealing either the probable cause or the signature would tantamount to alerting terrorists that they are in fact investigation, and that they can be tracked.

The risk to civil liberties is that there are no terrorists at all, and this is just a fishing expedition, or worse, persecution of some form.  The FISC and its appellate courts are intended to provide some level of protection against abuse, but in all other cases, the public as a view to whether that abuse is actually occurring.  Many have complained about a lack of transparent oversight of the FISC, but the question is how to have that oversight without alerting The Bad Guys.

The situation gets more complex if one considers that other countries would want the same right to demand information from their mail service providers that the U.S. enjoys, as Yahoo’s own transparency report demonstrates.

In short we are left with a set of difficult compromises that pit gathering of intelligence on terrorists and other criminals against the risk of government abuse.  That’s not Yahoo!’s fault.  This is a hard problem that requires thoughtful consideration of these trade offs, and the timing is right to think about this.  Once again, the Foreign Intelligence Surveillance Act (FISA) will be up for reauthorization in Congress next year.  And in this case, let’s at least consider the possibility that the government is trying to fulfill its responsibility of protecting its citizens and residents, and Yahoo! is trying to be a good citizen in looking at each individual request on its merits and in accordance with relevant laws.


* No I don’t know the difference between “unique” and “highly unique” either.

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How hard is it to secure a baby monitor?

Philips In.Sight B120/37Parents often seek the security of a baby monitor to know that their child is resting comfortably.  Unfortunately that security is often misplaced.  Last year Rapid7 produced a damning report, exposing numerous vulnerabilities in these devices.  As an example, the Philips In.Sight B120/37 made use of a fixed password over an insecure telnet or web service that resides on TCP port 8080.

Don AdamsThe thing is- the In.Sight came very close to getting right, or as the great Maxwell Smart would say, “Missed it by that much!”  That’s because Philips also offers a cloud-based service that would not otherwise require the device to listen to any TCP port.  That’s a good way to go because it is harder to probe the device for vulnerabilities.

One good reason to offer a local service is that some some people do not trust cloud services, and they particularly do not trust cloud services involving images of their children.  Indeed this makes for a very difficult choice, because that same Rapid7 report notes problems with some cloud based services, and so parents wouldn’t be wrong to worry.

Either way, I’ve built a MUD file using MudFileMaker.

A brief view of the application alongside tcpdump together with a quick view of the server binary seems to indicate that cloud communications are to api.ivideon.com.  We can thus come up with an appropriate MUD file as follows:

{
  "ietf-mud:meta-info": {
    "lastUpdate": "2016-10-03T12:56:08+02:00",
    "systeminfo": "Philips In.Sight B120/37 Baby Monitor",
    "cacheValidity": 1440
  },
  "ietf-acl:access-lists": {
    "ietf-acl:access-list": [
      {
        "acl-name": "mud-94344-v4in",
        "acl-type": "ipv4-acl",
        "ietf-mud:packet-direction": "to-device",
        "access-list-entries": {
          "ace": [
            {
              "rule-name": "clout0-in",
              "matches": {
                "ietf-acldns:src-dnsname": "api.ivideon.com",
                "protocol": 6,
                "source-port-range": {
                  "lower-port": 443,
                  "upper-port": 443
                }
              },
              "actions": {
                "permit": [
                  null
                ]
              }
            },
            {
              "rule-name": "entin0-in",
              "matches": {
                "ietf-mud:controller": "http://ivideon.com/babymonitors",
                "protocol": 6,
                "source-port-range": {
                  "lower-port": 8080,
                  "upper-port": 8080
                }
              },
              "actions": {
                "permit": [
                  null
                ]
              }
            }
          ]
        }
      },
      {
        "acl-name": "mud-94344-v4out",
        "acl-type": "ipv4-acl",
        "ietf-mud:packet-direction": "from-device",
        "access-list-entries": {
          "ace": [
            {
              "rule-name": "clout0-in",
              "matches": {
                "ietf-acldns:src-dnsname": "api.ivideon.com",
                "protocol": 6,
                "source-port-range": {
                  "lower-port": 443,
                  "upper-port": 443
                }
              },
              "actions": {
                "permit": [
                  null
                ]
              }
            },
            {
              "rule-name": "entin0-in",
              "matches": {
                "ietf-mud:controller": "http://ivideon.com/babymonitors",
                "protocol": 6,
                "source-port-range": {
                  "lower-port": 8080,
                  "upper-port": 8080
                }
              },
              "actions": {
                "permit": [
                  null
                ]
              }
            }
          ]
        }
      }
    ]
  }
}

Remember, the router needs to fill out which devices are authorized to be in class http://ivideon.com/babymonitors.  Note the use of incoming tcp port 8080.  It is possible at least for the server software run on another port if the configuration is changed.  At that moment, the above MUD file would be too restrictive, and the device would not function.  To fix that, one would simply remove the TCP port filter.

Again, note that only authorized communications are listed in the file, and so just because the developer left a telnet server in place doesn’t mean that just anyone would be able to access it.  This serves as a means to confirm the intentions of the developers.  Of course developers should never leave back doors, but if they do, perhaps MUD can reduce their impact, and let parents rest just a little easier.

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How MUD could help against the Krebs Attack

CybercrimeIn the attack against krebsonsecurity.com, one of the systems that is said to have been used was the “H.264 Network DVR“.  This device accepts HTTP connections, and communicates outbound using FTP and EMail.  There may also be an undocumented protocol for a proprietary interface.

As I’ve previously discussed, use of Manufacturer Usage Descriptions (MUD) can limit the attack surface of a device, and it can also prevent devices from being used to source an attack.    MUD allows for manufacturers to define classes, and now one simply needs to fill them in on deployment.  From the manufacturer’s side, one needs to provide the file.  For the DVR in question, I used MudMaker to create a description that a network device could use to create appropriate network protections:

{
  "ietf-mud:meta-info": {
    "lastUpdate": "2016-10-02T08:28:19+02:00",
    "systeminfo": "DVR H.264",
    "cacheValidity": 1440
  },
  "ietf-acl:access-lists": {
    "ietf-acl:access-list": [
      {
        "acl-name": "mud-65333-v4in",
        "acl-type": "ipv4-acl",
        "ietf-mud:packet-direction": "to-device",
        "access-list-entries": {
          "ace": [
            {
              "rule-name": "entout0-in",
              "matches": {
                "ietf-mud:controller": "http://dvr264.example.com/controller"
              },
              "actions": {
                "permit": [
                  null
                ]
              }
            },
            {
              "rule-name": "entin0-in",
              "matches": {
                "ietf-mud:controller": "http://dvr264.example.com/controller",
                "protocol": 6,
                "source-port-range": {
                  "lower-port": 80,
                  "upper-port": 80
                }
              },
              "actions": {
                "permit": [
                  null
                ]
              }
            }
          ]
        }
      },
      {
        "acl-name": "mud-65333-v4out",
        "acl-type": "ipv4-acl",
        "ietf-mud:packet-direction": "from-device",
        "access-list-entries": {
          "ace": [
            {
              "rule-name": "entout0-in",
              "matches": {
                "ietf-mud:controller": "http://dvr264.example.com/controller"
              },
              "actions": {
                "permit": [
                  null
                ]
              }
            },
            {
              "rule-name": "entin0-in",
              "matches": {
                "ietf-mud:controller": "http://dvr264.example.com/controller",
                "protocol": 6,
                "source-port-range": {
                  "lower-port": 80,
                  "upper-port": 80
                }
              },
              "actions": {
                "permit": [
                  null
                ]
              }
            }
          ]
        }
      }
    ]
  }
}

What is left for the controller to do that is specific to this device is define which devices are in the class http://dvr64.example.com.  That might include the FTP-based logging system that this model uses, for instance, as well as those systems that are authorized to connect to the HTTP port.

The important part of that description is what you don’t see.  You don’t see any of the attack vectors used, because through this whitelist approach, you only specify what is permitted, and everything else aside from name service and time queries is explicitly denied.  This device uses a good few services, and so I haven’t specified each one in the example for brevity’s sake.

This may well have stopped the hacker from gaining access to the device in the first place, and would have stopped the device from being able to attack the blogger, and many other attacks as well.

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