Abstract— Existing online social networks open the doors of socialization for their users by providing a few and easy steps towards user account creation. The major drawback of this feature is that current social network providers lack mechanisms of determining the authenticity of an account. A genuine user’s account can be easily forged with fake profile information. There is simply no mechanism to assign or bind any unique identity with user’s account that prevents its forged clone to be created on the same network or across multiple networks. One of the intentions of creating a forged account is to deceive the social circle of an individual and compromise their privacy. Accepting a friend's request from a forged account can badly compromise the privacy of an individual. All this can occur to the victim in a very short span of time before she discovers this attack and remove the fake identity holder from her friend's list. To tackle with the issue of identity theft and determining genuine user accounts in online social networks, we present in this paper a novel and real world's trust based approach for verifying the legitimacy of online social network accounts. We propose to use a verification process that utilizes the use of OpenPGP digital certificates and the web of trust consequently formed by them. We define two stages for our secure design. In the first stage, our approach requires digital certificates to be uploaded on the social network server at the time of user account creation. These digital certificates are verified to restrict forged account creation on the same network and across other social networks. In the second stage, to establish a new connection this digital certificate is sent along with the friend request to the recipient. The recipient verifies its authenticity based on the web of trust associated with that certificate. In order to implement our solution, we developed a social network prototype i.e. TrustBook. We conducted an experiment to evaluate the performance of our work against well know social networking site i.e. Facebook by launching forged account attacks on both. There were three performance metrics used in the experiment i.e. applicability, reliability and usability. The observations showed that our approach is applicable to all kinds of interaction scenarios. Also it has a good resilience against profile cloning and other kinds of security attacks including session hijacking, replay and channel jamming.
Keywords—OpenPGP; Web of Trust; Social Networks; Friend Request; Authentication
I. INTRODUCTION
Social networking websites have become an integral part of day to day human life. There are currently 1.11 billion facebook users with 150 billion total number of Facebook friend connections. Based on these statistics the average
number of friends each user has is 142 persons [1]. One major reason behind this accelerated usage of social networks is that people are getting more concerned about their virtual relations along with their in-person relations. Almost all direct relations are further connected through virtual relations provided by several online social networks. The access to the content shared by a user with her contact lists and the rest of the world is controlled by the privacy setting options provided by the service provider. To get benefit out of these privacy setting options, a user must also be careful in adding new friends to her account. Creating more than one account is a very common activity only if there is no bad intention behind it. But the dangerous thing about social networking sites is that there is no mechanism to confirm authenticity of the account. The service provider knows nothing else about the person except what she herself provides. Also such sites have less resistance against detecting automated bot attacks for creating forged accounts [2].
Adding a friend or finding some long lost friend over a social networking site seems a very innocent activity but in connection with a forged account it can compromise privacy and security of a person badly. The reason behind is that besides all good social networking sites have brought in our life, an important consideration is that social networking friendship establishment lacks verification and authentication mechanism. A person is never sure about whom he is establishing relation is the actual person (he is claiming to be) or not. As Facebook also contains sensitive private information for a person which he only wants to share with his or her community so any leakage of such information by connecting to a wrong person can bring several harms to the person. The severity of harm depends on the situation and can range from simple information leakage to cyber bullying, becoming a scam victim, damaging of public image, dismissal from the organization and relation break-up etc [3] [4].
Statistics show that Facebook users are usually not very conscious about verifying about the person before accepting him/her as a friend [2]. Here one major reason besides the curiosity of the person in accepting friend request is that the service provider does not provide any such mechanism through which a user can determine the authenticity of the person he is connecting to through social networking site. As a friend request just comprise of the person's name, photograph, a list of mutual contacts and any optional message. To find a friend in a social network requires search for a profile. Due to duplicate
2013 11th International Conference on Frontiers of Information Technology
user ID names, it is difficult to find an old friend. The need is that there should be some intuitive privacy and security aware mechanism through which the authenticity of the person connecting to can be verified.
Keeping in view the problem of user authenticity for initial relationship establishment, in this paper we propose to use PGP web of trust digital certification mechanism [5] for the purpose of verification. We also show how much suitable this approach is for applicability to all kinds of relationship establishment scenarios over social networks.
A web of trust is based on the notion of accumulating keys from other people whom we trust and suppose that other people trust also. Everyone has his own web of trust regarding verifying each other. This basic idea of forming a web of trust by signing each other's digital certificate arise from the concept of six degrees of separation [6], that tells any person in the world can find a link to any other person in the world with six on average or fewer than six, other people as intermediaries. This is a web of referees. Web of trust is therefore a decentralized web of referees for the world.
The contributions of this research work are:
1. A novel approach for secure relationship establishment is proposed based on the OpenPGP Web of trust.
2. Our approach provides a unique identification to a user in the same social network or in cross-site social network.
3. Applicable to all kinds of relationship establishment scenarios where people may have met in-person or not.
4. Our approach has a good resilience against same/ cross site profile cloning security attacks.
The paper is organized as follows. In section 2, we provide the motivation behind our problem domain. In section 3, we provide a brief description of PGP web of trust, its current implementation as GnuPG and the architectural design details for our proposed approach in social networking scenario. In section 4 the implementation details of our prototype are provided. In section 5, we discuss the security resiliency of our approach against multiple attacks. In section 6, we provide our experimental details of a user study to evaluate performance of our approach. In section 7, we discuss our related work. Finally in section 8, we conclude our research work along with other research directions that might be worked out in future.
II. MOTIVATION
Here in this section we provide a short history for creating forged accounts, social network identity theft and automated attacks launched to accomplish it.
The popularity and growth of OSNs are providing cyber criminals to launch different kinds of online attacks to compromise the privacy and security of individual persons and organizations. One such kind of attack is that of impersonation achieved through forged identities. These sites may contain some sort of sensitive information about their users which attracts attackers to launch attack. The basic profile information of a user is usually public for all others on a social network. It includes such information as name, contact list, educational background, occupation, location, likes and dislikes. Such information can be easily found through other sources as well
such as person's website, resume uploaded on corporate site. An attacker creates a forged account using this information which makes it difficult to distinguish from the actual one. Such an experiment was conducted by the authors of [7]. They created a cloned account for Marcus Ranum, a famous security expert on LinkedIn. Through this experiment the impact and extend of impersonation was observed. The cloned account received many friend requests. Even some closed family members of Marcus Ranum also sent him friend request.
Forged account attacks are usually launched through initial process of relationship establishment. As a result, adding some user as a friend or accepting a friend request requires great care as scammers, crooks, predators, stalkers and identity thieves can take the advantage of this innocent activity. This little act of carelessness even for a very short span of time can badly compromise a user's privacy before the fake contact is removed from the contact list.
The authors of [2] studied the feasibility and ease of automated crawling and identity theft attacks against five popular social networking sites i.e. XING, StudiVZ, MeinVZ, Facebook and LinkedIn by developing a prototype attack system called iCloner. The authors found that social networking sites are usually not well protected against automated crawling of code and access and most users of social networking sites are not much concerned about the authenticity of the sender during accepting new and unknown friend requests or clicking on unknown links sent to them. Further the system was capable of launching two kinds of attacks to access list of victim's contacts i.e. profile cloning and cross-site profile cloning. Profile cloning is creating fake cloned account on the same social network by sending a friend request with a misleading message like “Dear friends, my account is hijacked, I am reconstructing my friend list, please add me again!". As users are generally not cautious when accepting friend requests so the attack was successful. Cross-site profile cloning is more difficult to detect. The process involves identifying those victims that are registered in one social network, but not in another. The attacker mimics their identities and creates account based on the fake information for them in the network where they are not registered. This concept can be well understood with an example. Suppose the attacker selects two famous OSNs and send friend request to any ten user's on one OSN e.g. MySpace. Assume any five out of ten accepts the request. Their friend lists is collected. Now five more profiles are searched against a second OSN e.g. Facebook. Suppose three of them exist on the Facebook and are found by the attacker. Their friend lists are collected from the facebook as well. Now look for the friend who is present on MySpace but not on Facebook. A forged account is created for the absent friend by collecting his information from MySpace. A friend request is sent to the victim on the Facebook with this forged account. Now the actual game starts. The request has many chances to get acceptance but in fact, Facebook itself suggests the forged account as a friend to the friends of the victim.
The discussion concludes that there should be a mechanism of unique identification of a user in a social network and also across multiple social networks. There can multiple kinds of privacy threats through this kind of breach in privacy. In order to tackle this kind of situation, in this document we propose to
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work with the established infrastructure of westablish relationship over online social networks
III. TRUSTBOOK DESIGN
Here in this section we describe PGP web offormed and its suitability for online social nWhat is GnuPG implementation for PGP web ofwe accomplished it in our approach?
A. PGP Web of trust
In our daily life we require multiple kindsattestations, certificates and notaries that providesort of authentication. These mechanisms are fuby some other authorities with the right of notaexample government officers possess the rightperson's documents based on the showingdocuments. Our citizenship ID cards are also anThis whole process develops a hierarchical among multiple parties.
X.509 is an example for such a hierarchical[7]. X.509 requires all keys must be authenticaccredited organization before they can be communication. The certificate of this organiauthenticated by some other higher rankingorganization. This hierarchy goes up until we reathat is accredited by all certificates called as root
OpenPGP is another example of such kind o[8]. It is a bit different from X.509 as instead ofhierarchy it assembles digital certificates in suformulate a “Web of trust” that do not requirsingle certification authority. It models humabehavior as in our day to day life we trust peopldealing matters. For example, if user A trusts usA can also trust the digital certificate of user Cauthenticated by user B. OpenPGP is currentlGnuPG by IETF.
B. GnuPG
GNU Privacy Guard (GnuPG or GPG) is aGnuPG is the GNU project's complete and free iof the OpenPGP standard as defined by RFC 4the current IETF standards track specificationGnuPG can be freely used, modified and distribterms and conditions of GNU General Public Lic
GnuPG enables to encrypt and sign communication. It has a very sophisticated kesystem and also other access modules for all kkey directories. It can be run through a commandfeatures for easy integration with other applicanumber of frontend applications and libraries are
C. Digital Certificate Creation
In our work, we require a user to creacertificate using any frontend provided implementation (e.g GPG4win, Webpg). This for the fact that we are not restricting certiprocess to any particular social network serviceultimate goal is that the same certificate canacross multiple social networks service provider
web of trust to s.
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of references, e us with some
urther notarized arization. As an t of attesting a g of original
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requirement is ificate creation e provider. The n be employed rs as a mean of
authentication. Digital certificate creathat requires some basic details for geas name, email and passphrase. Once tprovides a user with the option of exof the key server (usually default certificate is exported to the key servrest of the servers in the world in 24 certificate anywhere in the world canrecipients email ID or just name. Frequires in the first step to import the sverification of the fingerprint providedthe signer and again uploaded on the formed for any imported certificate caeither as a signer or as a signee. Figurethe certificate details of a user named
Fig. 1. Certificate details of a user created usi
D. Proposed Architechture
After generating a digital certificatrust successfully, our prototype requexported on the server during accourestricted to provide the same emagenerating the certificate. It is made creation of profile on our prototype. creating forged account with someodifferent social network. Due to this fesocial network cannot be forged certificate on any other social networkmore than one certificate for the sdifferent accounts with same certificpurpose of cross-site connection autprofile information is the same as pnetwork service providers. Our prototyrevocation for the certificate based ocreated. While other added certificaupdated. Also it is notified to all conne
Figure 2 and 3 shows the archapproach. The exported certificates awith email ID and any other dupnetwork. If a match is found, profile original recipient of the certificate Otherwise a successful profile is create
ation is a simple process enerating a key pair such the certificate is created it
xporting certificate to one key server). Once the
ver it is replicated to the hours. Similarly a digital
n be searched with either Forming a web of trust signee's digital certificate, d and then it is signed by server. The web of trust
n be seen in two ways i.e. e 1 provides a snapshot of "maryam".
ing GPG4win windows tool kit
ate and forming a web of uire that certificate to be unt creation. The user is ail ID that he used for a mandatory step for the This restriction prevents
one else’s public key on eature a user on any other with the same digital
k. It is possible to upload ame profile but making
cate is disallowed for the thentication. The rest of provided by other social ype currently restricts key on which the account is
ates can be revoked and ections.
hitecture diagram of our are checked for a match licate certificate on the creation is blocked. The is informed via email.
In a new connection establishment, the sender just sends an invitation to the receiver. The service provider automatically sends the sender's certificate to the receiver for verification. The receiving person can verify the authenticity of the certificate through any front end implementation of GnuPG as described before.
We implemented our prototype social network using PHP and used MySQL as a backend database as shown in figure. Our prototype is a light weight application developed for windows platform. It can run on any single, multi-core processor desktop PC or laptop.
The prototype allows its users to create their accounts. Users can update their status and profile pages. Users can send friend request, accept incoming request and also delete friends from friend list shown in figure 4. All account information is stored in a database built using MySQL i.e. profile details, digital certificates and friend list.
Fig. 4. A User’s wall sample
V. PERFORMANCE EVALUATION METRICS
We evaluated the performance of our approach encountering two metrics i.e. applicability, reliability and usability. Applicability deals with the scenario coverage. Reliability is actually the security analysis of our approach in connection with resilience for multiple kinds of attacks. Usability deals with the user friendliness of the whole procedure as described in the experiment section.
A. Applicability
Our approach covers all kinds of connection establishment scenarios over social networks such as:
• People have met in person before establishing relation over social network
• People never met in-person before but they know each other
• People never met before, also do not know each other For the first two cases there are more chances that a user is
aware of the genuine public keys of their friends, as a result doesn't require much to investigate. But for the third case a user must be very careful during connection establishment. The user is suggested to look for real public keys of the sender and certifying persons and in case of a single conflicting value should disconnect the communication.
B. Reliability (Security Analysis)
In our case the main objective of the attacker is to impersonate in such a way that the victim is not able to identify this act of impersonation and as a result the fake friend request is accepted. For our scenario we think that attacker is also aware of the notion of web of trust. Suppose the attacker generate fake digital certificates and also have them certified with other fake digital certificates, thus develop a fake web of trust. Now if the attacker send friend request whether it is authenticated or not it depends on the context of the situation. Three kinds of cases are observed in this situation:
• The victim has mutual contacts in her web of trust • The victim do not have mutual contacts but she knows
about the real public key of the certifying person(s) • The victim do not have mutual contacts also she
doesn't knows about the real public key of the certifying person(s)
For the first two cases, it is not much difficult to identify an attack. For the third case the decision of accepting the friend request is totally dependent on the recipient user. As a suggestion a user should be more careful in this case and should search for the real digital certificates of the sender and the digital certificates of the associated certifying web of trust. Any single conflicting values should result in rejection of the friend request.
Our prototype disables creating forged account with someone else’s digital certificate as it looks for a match between email ID provided and digital certificate attached to it. Other kinds of attacks such as replay, session hijacking and channel jamming are also possible in our approach. But these attacks may cause delay in connection establishment but privacy will not be compromised in any way as a result of them. Also in all cases that we observed, there are more chances that the privacy is compromised due to the
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carelessness of the victimized person. Due to this fact our technique requires a complete knowledge of the usage of generating digital certificates, certifying certificates to form a web of trust and finally using them to interact by sending signed friend request or identifying genuine IDs in multiple social networks.
VI. EXPERIMENTAL EVALUATION
In order to evaluate the performance of our prototype we conducted an experiment with 30 participants randomly collected. We evaluated our approach against existing mechanisms for finding friends and sending friend request on Facebook. The aim of the experiment was to compare the performance of our approach and the existing techniques with respect to applicability, reliability and usability. The step wise details of the study are:
1. Basic profile information and the actual Facebook IDs of all the participants were collected
2. Forged accounts for all the participants were generated using their actual Facebook IDs and profile details on both Facebook and our prototype.
3. A practical connection establishment test was performed using our prototype and Facebook
4. At the same time forged accounts were also used to send friend request
A. User Sample Details We collected 30 participants from three different
disciplines of International Islamic University, Islamabad. All the participants were undergrad students with ages between 19 and 23. All of them had already accounts on Facebook and other social networking sites.
B. Experiment Details
The participants were randomly divided into two groups; we called it Group-A and Group-B. Group-A participants were tested for forged account attack on Facebook and Group-B participants were tested for forged account attack on our prototype. Group-A was unaware of forged account attack while Group-B participants were trained with the process of generating digital certificates using GnuPG implementation of PGP. Also they were asked to get it certify by their trusted authorities. Thus each participant was asked to have their certificates certified by at least three certifying persons. The certifying persons were mostly out of their domain and included their instructors and mutual friends. Group-B had a good awareness of web of trust and forged account attacks and how to verify the authenticity of an account.
Group-A participants were asked to add each other by sending friend request. Before that all of them were sent requests using their forged accounts. Our goal was to find the percentage of participants deceived by our forged account requests. Similarly Group-B participants were first asked to create accounts on our prototype with uploading their complete digital certificate information and the same email ID for which they generated digital certificate. Then they were asked to send each other friend request. Before that all of them were sent request using their forged accounts, some of the forged accounts also had fake digital certificates associated with them. Our goal was to find the percentage of participants deceived by
our forged account requests. We observed that with a very small training session of one hour, users were capable of doing the whole process with ease and the ratio of successfully detecting forged account attacks was high.
C. Observations
The observations of our results are summarized in table 1.
TABLE I. PERCENTAGE OF ACCEPTANCE RATE FOR FORGED ACCOUNTS AND GENUINE ACCOUNT REQUESTS
Group forged account genuine account A 80% 20% B 7% 93%
We also submitted a questionnaire to our participants to find the usability of our approach. The questions were related to the amount of time taken, complexity of the approach, scenario coverage, security of the approach and trust on the system as summarized in Figure 5-8. We found that our approach:
• Takes a reasonable amount of time in understanding the system and working with it.
• The overall process is equally complex as existing systems • Covers all kinds of interaction scenarios. • The system is more secure and trustworthy
Fig. 5. User Feedback regarding Time Taken by TrustBook
Fig. 6. User Feedback regarding procedure Complexity of TrustBook
Fig. 7. User Feedback regarding Security of TrustBook
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Fig. 8. User Feedback regarding Trustworthiness of TrustBook
VII. RELATED WORK
Other techniques proposed so far to address the issue of authenticity of social network accounts are [9], [10] and [11]. In [9], two users located in physical proximity take a picture of a common subject e.g. self-portrait. The pictures are complemented by spatiotemporal information are then uploaded by each user individually. Before establishing virtual links these pictures are compared to verify the existence of a prior physical interaction Scope: People must have met in person before, Overall process is not flexible as it has limited scope i.e. people must have met in person before interaction on social networks. Although replay and channel jamming attacks fail to compromise the privacy of a user but smart phone theft scenario are very common and if it happens what should be resilience mechanism in that case. The authors in [10] deal with impersonation issues among closed friends. The system requires sharing at first, some exclusive shared knowledge like any mutually agreed upon secret question among two existing friends using existing protocols. After they verify each other an exchange of public keys takes place. The approach is good for identifying closed friend but not scalable for other interaction scenarios. The major reason for which is that it requires the overhead of sharing exclusive shared knowledge among a pair of users whom must have met in person before.
The paper [11] is based on the assumption that facebook friends form a web of trust. Therefore in order to have secure communication between “two established facebook friends” on both in (over facebook) and out of band (using any messenger e.g. Pidgin) communication channels, facebook is used to store GPG public key material. Any instant messaging application such as pidgin automatically query this web of trusted friends and sets up trusted, encrypted channels of communication without specifically going through some additional process to get secure communication. If two users have the secbook application set up in the facebook, and the pidgin trust plugin installed in pidgin, then they do not have to do anything special to setup a secure communication channel, other than just start talking.
VIII. CONCLUSION
Relationship establishment in current online social networks is usually based on basic profile information of the requester i.e. name and photo. Besides hijacking of genuine social networks accounts, creation of forged user's profile is also becoming a severe threat in near future. Friend request from forged accounts can cause severe compromise to the privacy of an individual. In order to determine whether a friend request is from a genuine user account or not, we propose in this document a novel technique i.e. TrustBook. The idea is to
use OpenPGP/ GPG web of trust public key systems to find whether a friend request is legitimate or not. To achieve this goal, we developed a prototype OSN that provides the resource of sending friend request along with digital certificate to determine the authenticity of a person. We conducted a case study to evaluate the performance our proposed approach we found that PGP web of trust is best suitable for authentication over social networks as it provides maximum security and is applicable to all kinds of interaction scenarios. In future we aim to have a test with X.059 certificates and OpenPGP certificates in same and across multiple social networks.
REFERENCES
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[3] J. HOFFMAN, "As Bullies Go Digital, Parents Play Catch-Up," The New York Times, pp. 1-12, 04 December 2010.
[4] B. Schneier, "Social Networking Identity Theft Scams," Schneier on Security, 08 April 2009. [Online]. Available: http://www.schneier.com/blog/archives/2009/04/social_networki.html.
[5] Abdul-Rahman, "The PGP trust model," the Journal of Electronic Commerce, p. Vols. 10(3):27–31., 1997.
[6] S. M. a. N. Hamiel, "Satan is on My Friends List: Attacking Social Networks.," 2008. [Online]. Available: http://www.blackhat.com/html/bh-usa-08/bh-usa-08-archive.html.
[7] R. Housley, "Internet X.509 Public Key Infrastructure Certificate and CRL Profile," January 1999. [Online]. Available: http://www.ietf.org/rfc/rfc2459.txt.
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[9] T. F. M. H. Delphine Christin, A Picture is Worth a Thousand Words: Privacy-aware and Intuitive Relationship Establishment in Online Social Networks, San Francisco, CA, USA: Third International Workshop on Security and Privacy in Spontaneous Interaction and Mobile Phone Use (IWSSI/SPMU), June 12, 2011.
[10] N. S. B. B. Randy Baden, "Identifying Close Friends on the Internet," in Eight ACM Workshop on Hot Topics in Networks (HotNets-VIII), New York City, NY, USA, October 22-23, 2009.
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