Bitcoin success attracts hacking, phishing, and fraud

Bitcoin, a distributed digital currency that cryptographically verifies transactions, has recently seen a large increase in usage — the total amount of Bitcoins in circulation is now well over $1B US Dollars and each Bitcoin is today worth more than $100. By way of comparison, Gibraltar — a British Overseas Territory and a conventional tax haven — had an economy worth an estimated $1.275B in 2008.

Speculators, investors, and criminals alike have been drawn to the alternative currency in the hopes of exploiting its anonymity, its almost exponential rising exchange rate against conventional currencies, and its dominant position amongst non-governmental currencies. Its attraction to criminals is diverse: it has become the de facto equivalent of cash facilitating anonymous purchases of illegal goods, and the dramatic increase in the value of each Bitcoin has meant that Bitcoin wallets have become increasingly attractive targets for would-be phishers.

Mt. Gox Phishing Site

A recent phishing attack against the leading Bitcoin Exchange, Mt. Gox

Bitcoin users are no strangers to being targeted by criminals: last month, attackers were able to steal $12,000 worth of Bitcoins from Bitinstant, a Bitcoin transaction services company, by obtaining the credentials for a brokerage account after socially engineering access to their emails. Malware writers have also targeted Bitcoins: Infostealer.Coinbit is a Trojan horse that tries to steal Bitcoin wallets. Criminals have also been using networks of infected computers to mine Bitcoins for themselves.

Bitcoin exchanges, organisations converting between Bitcoins and conventional currencies, are an obvious target for fraudsters. Last Thursday Mt. Gox (the leading Bitcoin exchange) faced a “stronger than average” DDoS attack. In September 2012 Bitfloor (another Bitcoin exchange) suspended operations after the theft of ~24,000 BTC (worth $250,000 at the time), and the Bitcoin exchange, Bitcoinica, went out of business after also suffering from large thefts.

Despite the apparent risk of operating in this business, some organisations are promoting a laissez-faire attitude to security to the Bitcoin community: BitPay recommends that merchants "[..] can eliminate the need for PCI Compliance and expensive security measures" by replacing credit card transactions with Bitcoin-based solutions.

Netcraft can provide Phishing Site Takedown and Countermeasures services, PCI Approved Vulnerability Scanning and Penetration Testing to Bitcoin exchanges, merchants, and e-commerce sites. For more information, please contact sales@netcraft.com. Internet users can be protected against phishing sites, Bitcoin-related or otherwise, by Netcraft's Anti-Phishing Extension. Help protect the internet community by reporting potential phishing sites to Netcraft by email to scam@netcraft.com or at http://toolbar.netcraft.com/report_url.

PHP just grows & grows

Netcraft began its Web Server Survey in 1995 and has tracked the deployment of a wide range of scripting technologies across the web since 2001. One such technology is PHP, which Netcraft presently finds on well over 200 million websites.

PHP Trend

The first version of PHP was named Personal Home Page Tools (PHP Tools) when it was released by Rasmus Lerdorf in 1995. PHP 1 can still be downloaded today from museum.php.net. Weighing in at only 26 kilobytes in size, php-108.tar.gz is diminutive by today's standards, yet it was capable of allowing users to implement guestbooks and other form-processing applications.

PHP 2 introduced built-in support for accessing databases, cookie handling, and user-defined functions. It was released in 1997, and by the following year, around 1% of sites on the internet were using PHP.

However, PHP 3 was the first release to closely resemble today's incarnation of PHP. A rewrite of the underlying parser by Andi Gutmans and Zeev Suraski led to what was arguably a different language; accordingly, it was renamed to simply PHP, which was a recursive acronym for "PHP: Hypertext Preprocessor". This was released in 1998 and the ease of extending the language played a large part in its tremendous success, as this aspect attracted dozens of developers to submit a variety of modules.

Andi Gutmans and Zeev Suraski continued to rewrite PHP's core, primarily to improve performance and increase the modularity of the codebase. This led to the creation of the Zend Engine, which was used by PHP 4 when it was released in 2000. As well as offering better performance, PHP 4 could be used with more web servers, supported HTTP sessions, output buffering and several new language constructs.

By September 2001, Netcraft's Web Server Survey found 1.8M sites running PHP.

PHP 5 was released in 2004, and remains the most recent major version release today (5.4.11 was released on 17 January 2013). Zend Engine 2.0 forms the core of this release.

By January 2013, PHP was being used by a remarkable 244M sites, meaning that 39% of sites in Netcraft's Web Server Survey were running PHP. Of sites that run PHP, 78% are served from Linux computers, followed by 8% on FreeBSD. Precompiled Windows binaries can also be downloaded from windows.php.net, which has helped Windows account for over 7% of PHP sites.

Popular web applications that use PHP include content management systems such as WordPress, Joomla and Drupal, along with several popular ecommerce solutions like Zencart, osCommerce and Magento. In January 2013, these six applications alone were found running on a total of 32M sites worldwide.

PHP also demonstrates a strong installation base across web-facing computers that are found as part of Netcraft's Computer Counting survey. Just as an individual IP address is capable of hosting many websites, an individual computer can also be configured to have multiple IP addresses. This survey allows us to identify unique web-facing computers and which operating systems they use regardless of how many sites or IP addresses they have. As of January 2013, 2.1M out of 4.3M web-facing computers are running PHP.

PHP has also become a victim of its own success in some respects: With so many servers running PHP, and with so many different web applications authored in PHP, hackers are presented with a huge and rather attractive attack surface. Because it is so easy to get started with programming in PHP, it attracts all levels of developers, many of whom may produce insecure applications through lack of experience and attention to detail. Netcraft's anti-phishing services find wave upon wave of phishing attacks hosted on compromised PHP applications, and the U.S. NVD (National Vulnerability Database) contains several thousand unique vulnerabilities that relate either to PHP itself, or to applications written in PHP.

Methodology

The full list of hostnames from the Netcraft Web Server Survey forms the basis of our technology tracking. We make requests to each of these sites, or if there is a large number of sites hosted on a single IP address, we employ a proportional sampling technique. The content of each page and its HTTP headers are analysed to determine which technologies are being used. For PHP, we look for references to .php filename extensions or the existence of HTTP response headers like "X-Powered-By: PHP". Additional signature tests are used to identify particular PHP applications, such as WordPress.

Each metric is then calculated as follows:

Hostnames

For each IP address, we estimate the total number of PHP sites it serves by calculating the product of the proportion of sampled hostnames that are running PHP and the total number of hostnames on that IP address. In cases where the IP address is serving 100 or fewer sites, all sites will be sampled and thus be representative of the entire population for that IP address.

Active sites

To provide a more meaningful metric which counts the number of human-generated sites actively using PHP, our active site count excludes spam sites or other computer-generated content. This methodology is described in more detail here.

IP addresses

This metric counts the number of unique IP addresses where at least one hostname in its sample set was found to be running PHP.

Computers

A single physical or virtual computer may have more than one IP address. We are able to identify unique computers that are exposed to the internet via multiple IP addresses. If an IP address is running PHP, then the computer associated with it is marked as running PHP. Further details of this methodology are explained in our Hosting Provider Server Count.

CloudFlare accelerates 235,000 websites

Just over two years since its launch, the CloudFlare content distribution network is being actively used to accelerate traffic to more than 235,000 websites in Netcraft's Web Server Survey. In total, we found 785,000 sites currently configured to use CloudFlare's DNS servers. Once a domain has been configured to use these servers, any of its subdomains can be routed through the CloudFlare system at the click of a button. Paying customers can also route their traffic through CloudFlare by setting up a CNAME within their own DNS.

CloudFlare's network is globally spread across 23 datacenters, half of which are entirely remotely operated. Nine of these datacenters were opened during a month-long expansion effort which ended in August and resulted in a 70% increase in network capacity. CloudFlare's content distribution network spreads website content around these datacenters, allowing visitors to request pages from geographically closer locations. This typically reduces the number of network hops, resulting in an average request taking less than 30ms.

In addition to moving static files closer to visitors, CloudFlare also offers an automatic web optimisation feature called Rocket Loader. This combines multiple JavaScript files into a single request, which saves both time and bandwidth. Pro, Business and Enterprise users can also enable beta support for SPDY requests, which achieve better latency than HTTP through the use of compression, multiplexing and prioritisation.

In October, CloudFlare introduced support for OCSP stapling, which it claims has increased the speed of SSL requests by 30%. The Online Certificate Status Protocol allows browsers to ask a certificate authority (CA) whether an SSL certificate it has issued has been revoked. Handling these requests in realtime can be challenging, particularly if the CA has issued a large number of certificates, or has issued certificates to extremely busy websites. OCSP stapling solves this problem by delivering the OCSP response directly from CloudFlare's network, removing the need for the browser to perform an additional DNS lookup and send a request to the CA's own OCSP server. OCSP performance is often overlooked when considering which CA to buy a certificate from, but can have a crucial impact on the overall performance of a customer's website.

With its insight into the kind of requests being sent to many different websites, CloudFlare is well-positioned to identify malicious traffic and provide protection to all of its customers. Depending on which level of security is enabled, CloudFlare can deny requests which are attempting SQL injection attacks, comment spam, excessive crawling, email harvesting, or exploiting cross-site scripting vulnerabilities. Business and Enterprise users can also benefit from CloudFlare's advanced DDoS (distributed denial of service) protection.

CloudFlare's growth accelerated significantly in the summer of last year. This is when many people first became aware of the service, after it was used to handle traffic for the Lulz Security website. High profile attacks against Sony, Fox, PBS and the X Factor helped LulzSec garner 350,000 followers on Twitter, where it extolled the virtues of using CloudFlare to mitigate DDoS attacks.

Some notable high-traffic users of CloudFlare include The Hacker News, Uber Humor, Android firmware site Cyanogen Mod, and the content management system Moodle.

Minimum RSA public key lengths: guidelines or rules?

The length of an RSA public key gives an indication of the strength of the encryption — the shorter the public key is; the easier it is for an attacker to brute-force. An attacker, armed with a compromised private key derived from a short public key, would be able to decrypt both past and future SSL-secured connections if she were able to incept the encrypted traffic. She could also impersonate the organisation to which the SSL certificate was issued if she has the opportunity to manipulate DNS lookups. Both the CA/B Forum (a consortium of certificate authorities (CAs) and major browser vendors) and NIST [PDF] (the agency which publishes technical standards for US governmental departments) have recommended that sub-2048-bit RSA public keys be phased out by the end of 2013.

According to the CA/B Forum's own Baseline Requirements [PDF] — effective 1st July 2012 — member certificate authorities are required to reject a request to sign an RSA public key shorter than specified in the following table:

Certificate expiry date Minimum RSA public key length
On or before 31st December 2013 1024
After 31st December 2013 2048

Nevertheless, these key sizes are not guaranteed as several CA/B Forum members have issued several non-compliant SSL certificates since 1st July 2012. Trustwave, Symantec, KEYNECTIS, and TAIWAN-CA have all signed certificates which fall foul of their organisation's requirement of 2048-bit RSA public keys for certificates expiring after 2013, demonstrating that the key length requirement is being treated as a guideline (which by definition is neither binding nor enforced), rather than a rule.

They are by no means the only CAs signing short RSA public keys: more than 10 years after Netcraft's first blog post on the topic and 12 years after RSA-155 [PDF], 512-bit RSA public keys are still appearing in SSL certificates. A 512-bit RSA public key was signed as recently as July 2012 by Swisscom.

Most, but not all, of the major browser and operating system vendors either disallow access or display a warning message when accessing a website using an SSL certificate with a 512-bit RSA public key. The latest versions of Safari (although not the mobile version on iOS 5.1), Opera, Google Chrome, and Internet Explorer (via an update to Windows; planned to be rolled out in October 2012). Notably, Mozilla Firefox does not yet reject such certificates.

Governments and banks still using weak MD5-signed SSL certificates

More than a thousand websites – including several government sites – are still using SSL certificates with weak signature algorithms.

Netcraft's August 2012 SSL Survey shows there are 1,300 websites still using SSL certificates that have been signed using the cryptographically weak MD5 digest algorithm. This algorithm is demonstrably vulnerable to several types of attack, including collision attacks.

The first use of this vulnerability against SSL was demonstrated back in December 2008, when security researchers showed how an MD5 hash collision could be exploited to create a rogue certificate authority (CA) certificate that would be trusted by all common web browsers. This rogue certificate could have been used to sign arbitrary subscriber certificates, thus allowing an attacker to convincingly impersonate any secure website on the internet.

At the time of the 2008 discovery, Netcraft's SSL Survey showed that 14% of all SSL certificates were signed using the vulnerable MD5 algorithm.

A few months later, the developers of Google Chrome suggested that some browser developers would be dropping support for MD5-signed certificates at some point; however, given the number of sites still using MD5-signed certificates, it was thought that suddenly removing support for such certificates would have a undesirably large impact on users.

As the majority of MD5-signed certificates have since expired or been replaced, browser vendors and certificate authorities have been gradually phasing out support for such certificates. Apple removed support for MD5-signed certificates in an iOS 5 update last year, and Chrome's developers subsequently revisited the issue and revised their browser to display an interstitial warning about MD5 being a weak signature algorithm. This immediately caused problems for users of certain corporate proxies, where a man-in-the-middle approach was used to decrypt SSL traffic before presenting it to the client with a trusted MD5-signed certificate.

The CA GeoTrust has added the affected certificates to its certificate revocation lists at http://www.geotrust.com/resources/repository/crls/, which has resulted in the certificates being rejected as invalid in many of today's browsers, including Chrome, Opera and Internet Explorer. However, sites which currently use MD5-signed certificates can be viewed with the latest version of Mozilla Firefox without receiving any warnings, as the relevant certificate revocation lists have to be added manually, and none of the certificates specifies an OCSP server for checking the revocation status.

The CA/Browser Forum Baseline Requirements for the Issuance and Management of Publicly-Trusted Certificates [pdf] no longer allow the MD5 digest algorithm to be used for root, subordinate or subscriber certificates. All but two of the 1,123 unique MD5-signed certificates still in use on the web were issued by Equifax between 2006 and 2008, with validity periods ranging between 4 and 6 years.

The remaining two MD5-signed certificates were issued by VeriSign. These do not appear to have been revoked, but are due to expire in less than a month. In the worst case, all MD5-signed certificates currently in use on the web will have expired naturally by March 2014, regardless of whatever measures have been taken by browser vendors and certificate authorities.

Several government websites are currently operating with MD5-signed certificates, including a few in Australia, a couple in New Zealand, and one in each of Ireland and the UK. The most recently issued certificates are marked as being valid from 30th December 2008 – the same day as the publication of the hash collision demonstration.

Other notable users of weak MD5-signed certificates include Reliance Bank, Commencement Bank, several online billing websites, dozens of corporate webmail services, purportedly secure hosting providers, a number of schools and universities, and even a reseller of GeoTrust SSL certificates.

LulzSec fuels growth at CloudFlare

Nine months after its launch, content distribution network CloudFlare is now used by more than 40 thousand sites in Netcraft's web server survey. The company announced its public beta at TechCrunch Disrupt in September 2010, where it came in as a close runner-up. Despite not winning, CEO Matthew Prince later described how Disrupt brought his team together and resulted in an increase in signups without having to carry out any additional PR or marketing.

CloudFlare also gained customers after recent praise from LulzSec, who use the service to run their website at lulzsecurity.com. LulzSec have accrued more than 200 thousand followers on Twitter as a result of their attacks against high-profile targets such as Sony, Fox, PBS and the X Factor.

When a website uses CloudFlare, client requests are made to a global network of edge nodes rather than to the website itself. This can increase performance, particularly when an edge node is located somewhere that can respond faster than the website's original hosting location.

By monitoring site traffic, CloudFlare can also offer some protection against denial of service attacks. When malicious traffic is detected, it can be automatically blocked at the edge nodes, before the traffic hits the website. Matthew Prince reported some DDoS attacks against CloudFlare yesterday, but noted that the service had not been impacted.

However, AnonNews used to be a prominent user of CloudFlare until the service was disabled after a DDoS attack affected the CloudFlare network. With traffic instead being routed directly to the server hosting anonnews.org, it has been seemingly unable to withstand the current series of attacks against it. The domain is registered to Sven Slootweg, who told Netcraft, "They had to turn it off on my domain for the past few days because of a really large DDoS attack." He added, "It apparently seriously affected their network. There is one or more Turkish patriot hacker groups constantly attacking AnonNews."

Nonetheless, CloudFlare's growth is continuing at a strong rate. The accessibility and cost of the service is undoubtedly playing a large part in this success – no contracts are required, and users can either sign up for free, or pay only $20 per month for a Pro account which offers better performance, advanced security protection and real-time stats. CloudFlare will also be offering an enterprise service soon.