1 Anonymous online purchases with exhaustive operational security Vincent Van Mieghem, Johan Pouwelse Abstract—This paper describes the process of remaining anonymous online and its concurrent operational security that has to be performed. It focusses particularly on remaining anonymous while purchasing online goods, resulting in anonymously bought items. Different aspects of the operational security process as well as anonymously funding with cryptocurrencies are described. Eventually it is shown how to anonymously purchase items and services from the hidden web, as well as the delivery. It is shown that, while becoming increasingly difficult, it is still possible to make anonymous purchases. Our presented work combines existing best-practices and deliberately avoids untested novel approaches when possible. Index Terms—OPSEC, online anonymity, bitcoin, hidden web, Tor, Dark Markets. F INTRODUCTION of incriminating evidence on those assets. Op- E present a detailed approach to anony- erational security, hereafter OPSEC, plays a W mously purchase goods and services on- critical role in remaining anonymous online. line. Anonymity does not work retroactively. At As human life shifts towards the world wide the beginning of an anonymous operation, the web, the interest of large Internet companies anonymity of all the assets involved have to and government agencies in the Internet in- be thought of very carefully. The environment creases significantly. Remaining anonymous on that will protect the anonymity has to be set up the Internet has ever before been as hard as it is thoroughly, from the beginning. The following today. Every webpage visited, every file down- subsections go into depth on the principles that loaded, every email or message sent, every ensure a high level of anonymity. purchase made, can be traced back and read by other parties. This paper describes the methods of remaining anonymous on the Internet and 1.1 Compartmentation the concurrently required operations security One of the key principles of OPSEC is applying processes. The first section explains the basic arXiv:1505.07370v1 [cs.CR] 27 May 2015 compartmentation. Compartmentation is the principles and tools regarding the operations limiting of the ability for persons or entities security, also known as OPSEC. Thereafter, the to access information needed to perform cer- process of obtaining anonymous bitcoins is de- tain tasks and isolating information as much scribed and finally the methods of purchasing as possible. In this case it means that all the online goods is explained. digital evidence and information should be (if possible physically) separated from each other 1 EXTENSIVE OPERATIONAL SECURITY so that linking pieces of information is hard Remaining anonymous on the internet is a and cannot be used to extend the image of though process. Anonymity cannot be obtained the anonymous identity that a person is using. through just the usage of certain tools or ser- Straight forward examples are: vices. It is a process that comes by keeping ev- • Possessing and using different online ac- ery single asset involved in the anonymous op- counts (i.e. Facebook or IRC nicknames) to eration, anonymous and minimise the amount sign up for anonymous services online. 2 Fig. 1. Elements of anonymous purchasing process. • Using different anonymous (prepaid) in OPSEC. credit card accounts to make purchases. • Removing XMP metadata (that may con- 1.2 Online identity tain geolocation data) from photo’s that a person uploads during the operation. Depending on the kind of operation, the fake LulzSec member W0rmer was exposed by identity that will be used, has to be as authen- not removing XMP data from a picture that tic as possible. A layered approach is used, contained geo-location of his girlfriend [7], meaning that one would create a fake online which linked to his real identity. identity and completely compartmentise this identity from its real identity. This fake iden- But compartmentation goes as far as: tity would then be used to create other fake • Using numerous hardware, i.e. mobile identities. It ensures that if one fake identify phones, laptops and CD-R’s (USB-devices gets compromised, it would not lead to de- contain microcontrollers that can be re- anonymization of the person’s real identity, but programmed into a spying device[8]), for instead just one ‘layer’ or ‘compartment’ of the doing different operations or components identity protection would have been ‘peeled of an operation. off’. In practice this means that created email • Spoofing MAC-addresses that are used to addresses point consequently only to the email identify hardware.[9] address of its previous ‘layer’ and not layers • Using different physical internet connec- beneath its previous ‘layer’. tions for different parts of an operation, As in other OPSEC practices, avoiding i.e. bars, hotels, open or hacked WiFi net- contamination and profiling between the works. LulzSec hacker Jeremy Hammond ‘wrapped’ identities is vital. was caught by identifying his laptop using the MAC-address found on his personal 1.3 Linking assets in real life WiFi network[9]. The purchase of online goods will in almost • Doing parts of an operation in differ- ent timezones, including never discussing every case, involve the physical contact of the environmental aspects, i.e. weather con- person with entities that may be able to gen- ditions. Hammond also revealed a large erate identifying material of the person’s real amount of profiling information during identity. In general one should always try, for IRC chats, that were used to personally every asset involved, to prevent purchases in identify him.[9] stores with camera surveillance and, obviously, never use electronic payment methods that • Removing any type of logs, i.e. syslog, chat logs from the operating system. may link to the real identity. It should not be possible for an observer of a 1.3.1 Purchase of hardware persons online activity to link properties of dif- In general, purchasing any kind of hardware ferent compartments to each other. Every step via online marketplaces12 is good practice (un- or move online has to be advised of not linking less the hardware is already blacklisted due compartments and extending the online image to past usage in compromised operations). of the real identity. This effect is referred to as contamination. To prevent this, the general 1. http://marktplaats.nl principle ‘proactively paranoid’ is often used 2. https://ebay.com 3 Second hand hardware has reduced tracking the easiest component to perform correctly in perspectives which otherwise may lead to the an anonymous operation. In general, open- de-anonymisation of the person’s real iden- source software projects that are end-to-end tity. By purchasing hardware in stores, the encrypted are used for secure communication. person becomes vulnerable to in-store camera The methods described in the following sec- systems. To minimise exposure, only purchase tions are, as of the moment of writing, ex- from small local stores and start to use the tremely secure, as concluded from N.S.A. doc- hardware only a few months after. If unique uments from the Snowden-leaks[1]. hardware ID’s may link to the time and lo- cation of purchase, the probability that the 1.4.1 Email owner of the store has already removed video One or multiple anonymous email accounts are evidence of the moment of purchase, is larger. required that do not have personal linked in- Making purchases in extreme weather condi- formation in them. Safe-mail3 is a provider that tions and dressing accordingly, may provide provides email with minimal personal informa- extra cover without drawing attention, i.e. sun- tion upon sign-up. Gmail also allows for easy glasses/scarf and cap. If hardware is bought sign-up, although is more monitored[11] and online, it must never be delivered to the per- sign-up over Tor requires phone verification. son’s address or be paid with electronic pay- This email account will be used together with ment systems other than anonymous prepaid GnuPG encryption of e-mails. Usage of keys credit cards and anonymised cryptocurrencies. longer than 4096-bit is important and authenti- It should be noted that spendings of prepaid cation tokens to protect the GnuPG private key credit cards are monitored[10]. provide an extra layer of security. Descriptive subjects should be avoided, as subjects of e- 1.3.2 Mobile Phones and SIM cards mails are not encrypted. Only when usage of mobile phones in an operation is mandatory, they should be used. 1.4.2 IM Due to easy localisation[4] and decryption of For Instant Messaging, a protocol named Off- communications[3], this medium is considered The-Record (OTR)[5] can be used. This is a insecure. Mobile phones should be disposable, XMPP-based protocol, that can be used to com- featuring a minimal OS and functionalities, re- municate over Jabber services, i.e. securejab- sulting in a reduced attack surface. The phones ber.me or CCC.de XMPP service4. Password should be used in combination with multiple renewal on regular basis is important practice. sim cards. Phones that will not be used any- XMPP services that provide self-signed certifi- more should be completely destroyed. While cates, signed with their GnuPG private key, phones are not used, the devices should be provide an extra layer of security against PKI battery unplugged or stored in a leaden box to attacks[2]. prevent emission of signals, especially when a 1.4.3 Voice smartphone or WiFi device is used. The phones should never be used to make phone calls Open Whisper Systems is a group of open- under the real identity of the person. Again, source contributors that build end-to-end compartmentise and avoid contamination of secure communication tools. RedPhone/Signal those compartments.