Category Archives: Security

Telephone-based Payment Card Data PCI Guidelines

The Security Standards Council (SSC) has released an information supplement on telephone-based payment card data. This is an update to PCI SSC FAQ 5362.

It now is clear that controls must be in place to clean and protect audio recordings; they violate PCI compliance if they store sensitive authentication data (SAD).

It is a violation of PCI DSS Requirement 3.2 to store any sensitive authentication data, including card validation codes and values, after authorization even if encrypted. It is therefore prohibited to use any form of digital audio recording (using formats such as WAV, MP3, etc.) for storing CAV2, CVC2, CVV2 or CID codes after authorization if that data can be queried; recognizing that multiple tools exist that potentially could query a variety of digital recordings.

The last sentence is the big clue. Known query tools pose a clear and present threat to SAD in audio files. The point of this supplement is to emphasize that the data needs to be protected due to the ease of querying and reading it. The controls must be documented and validated as usual.

The supplement provides a decision process flow to help illustrate different control areas. Even if no calls are recorded, for example, “Processing and transmission of cardholder data remain in scope for PCI DSS”.

One area of ambiguity remains.

Note the end of the sentence above where the Council says storage is prohibited “if that data can be queried”. Despite SAD media storage being prohibited there are some particular situations of storage — with additional controls — that may be allowed.

If these recordings cannot be data-mined, storage of CAV2, CVC2, CVV2 or CID codes after authorization may be permissible as long as appropriate validation has been performed. This includes the physical and logical protections defined in PCI DSS that must still be applied to these call-recording formats.

A call center, which can validate recordings can not be data-mined, thus may be allowed to store SAD. However, at the same time the supplement says they are prohibited from storing SAD.

Pay particular attention to sensitive authentication data: Storage is not permitted.

All clear?

I wonder if the PCI Council has the humor to start a campaign called “SAD is bad. Get rid of it and be glad”. They could even distribute it as a song, in an audio file.

US to Follow Chinese Common Cell Power Rule

China was said to be trying to reduce waste when it passed a rule five years ago that all mobile devices must be charged by a common USB interface.

China, through YD/T 1591-2006 “Technical Requirements and Test Method of Charger and Interface for Mobile Telecommunication Terminal Equipment,” created a requirement that cell phones must be charged from a USB charger.

[…]

To converge all the external connection functionality onto a single USB interface, several problems need to be solved, including routing audio over the same interface as data, detecting what external accessories are connected, maintaining high performance for all devices, and keeping power low.

Europe followed in 2009. Now, despite Apple’s best efforts to deploy annoyingly proprietary interfaces, ComputerWorld says the US will follow the Chinese USB rule.

By January 2012, all U.S. cell phones will have a common micro-USB interface that will allow universal external power chargers to use the port, CTIA Chairman Dan Hesse announced at a keynote at CTIA here today.

The variety of charging ports used in cell phones and smartphones today has irritated American users for years, especially as Europe moved forward on a common micro USB interface for data devices.

Oh, that’s funny, ComputerWorld does not mention the Chinese at all.

I agree with their assessment of American irritation. One of the reasons I dumped every electronic device I owned with iPhone/iPod interface a couple years ago was because I moved to a USB-only rule at home and at work. I have been surprised to find hotel rooms and gyms with electronics that have Apple proprietary interfaces. It’s like seeing a treadmill with a Betamax slot.

Bottom line is that availability of power will go up while waste goes down with a rule like this. There are compromises in features and maybe even functionality, but availability improvements and waste reduction seem worth it to me.

MHTML Exploit Evolution and Warning

Michal Zalewski includes an important paragraph towards the end of his analysis of the MHTML exploit affecting Google users as well as “a significant proportion of all sensitive web applications on the Internet”.

Based on this 2007 advisory, it appears that a variant of this issue first appeared in 2004, and has been independently re-discovered several times in that timeframe. In 2006, the vendor reportedly acknowledged the behavior as “by design”; but in 2007, partial mitigations against the attack were rolled out as a part of MS07-034 (CVE-2007-2225). Unfortunately, these mitigations did not extend to a slightly modified attack published in the January 2011 post to the full-disclosure mailing list.

Great to see the evolution has been included in the discussion. That was one of my points in my BSidesSF presentation when I criticized Symantec and McAfee for their analysis of certain infamous incidents. It felt like it was becoming too easy for security analysts to push the ZOMG button instead of taking time to trace and explain the development path that attackers followed. Certain shortcuts taken by Microsoft in 2007, for example, could have been called out for leading to problems the following year and especially in 2009. Instead security research is often given incentives to make a discovery look unique (“Download our new ZOMG report now! Try our new anti-ZOMG product!”).

Risk happens. But security can do itself a great disservice if it does not try to take mistakes back to product management and convince them to apply a corrective/new risk formula for the future — breaches should be traced back to decisions whenever possible.

This attack is focused more on a server flaw than prior iterations, which seems innovative, but it still has a lineage.

In other words, if we become too hasty and label a breach as an amazing state-sponsored intelligence effort, we allow vendors to claim it was impossible to see and the cost of prevention too high to achieve (until now, with a handy new ZOMG tool); instead, they would be given less wiggle room and more responsibility for quality engineering if security teams provide a logical progression of warnings and opportunities that showed where they could have fixed the issue much earlier.

Kudos to Zalewski on that account. His post is excellent. I also really like his vendor-neutral recommendations and that he offers defensive suggestions for both server and client.

It appears that the affected sites generally have very little recourse to stop the attack: it is very difficult to block the offending input patterns perfectly, and there may be no reliable way to distinguish between MHTML-related requests and certain other types of navigation (e.g., loads). A highly experimental server-side workaround devised by Robert Swiecki may involve returning HTTP code 201 Created rather than 200 OK when encountering vulnerable User-Agent strings – as these codes are recognized by most browsers, but seem to confuse the MHTML fetcher itself.

Until the problem is addressed by the vendor through Windows Update, I would urge users to consider installing a FixIt tool released by Microsoft as an interim workaround.

How the Dutch WiFi Hacker Escaped Conviction

Technically he was convicted on a separate charge so he did not go free, but he charges against him for hacking into a WiFi network were dismissed. PC World gives the following explanation:

A computer in The Netherlands is defined as a machine that is used for three things: the storage, processing and transmission of data. A router can therefore not be described as a computer because it is only used to transfer or process data and not for storing bits and bytes. Hacking a device that is no computer by law is not illegal, and can not be prosecuted, the court concluded.

The prosecution had to prove the wireless router was used for storage, processing and transmission of data. That sounds not terribly hard to do (a router is used to store logs and route data, packets are processed and transmitted), but apparently they proved only one or two, not all three. Also, if the law had used the word “or” instead of “and” (storage, processing or transmission of data) the judge might have found a different result. The ruling was appealed.