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Graffiti Networks: A Subversive, Internet-Scale File Sharing Model

Andrew Pavlo, Ning Shi

TL;DR

The paper addresses the insufficiency of long-term data persistence and anonymity in conventional P2P file sharing. It proposes Graffiti Networks, a three-party model where a tracker directs clients to store replicated data on public third-party storage sites, enabling months- to years-long availability through an asynchronous tit-for-tat protocol. A prototype integrated with BitTorrent demonstrates that data can be sustained on open web platforms for nearly a year, with about 40% of replicas remaining after deployment, highlighting a real security threat to operators of such sites. The work underscores the need for mitigations (e.g., CAPTCHA, site lockdown) and discusses potential adaptations, including botnet-like data storage applications, while suggesting Graffiti Networks could complement existing P2P ecosystems rather than supplant them.

Abstract

The proliferation of peer-to-peer (P2P) file sharing protocols is due to their efficient and scalable methods for data dissemination to numerous users. But many of these networks have no provisions to provide users with long term access to files after the initial interest has diminished, nor are they able to guarantee protection for users from malicious clients that wish to implicate them in incriminating activities. As such, users may turn to supplementary measures for storing and transferring data in P2P systems. We present a new file sharing paradigm, called a Graffiti Network, which allows peers to harness the potentially unlimited storage of the Internet as a third-party intermediary. Our key contributions in this paper are (1) an overview of a distributed system based on this new threat model and (2) a measurement of its viability through a one-year deployment study using a popular web-publishing platform. The results of this experiment motivate a discussion about the challenges of mitigating this type of file sharing in a hostile network environment and how web site operators can protect their resources.

Graffiti Networks: A Subversive, Internet-Scale File Sharing Model

TL;DR

The paper addresses the insufficiency of long-term data persistence and anonymity in conventional P2P file sharing. It proposes Graffiti Networks, a three-party model where a tracker directs clients to store replicated data on public third-party storage sites, enabling months- to years-long availability through an asynchronous tit-for-tat protocol. A prototype integrated with BitTorrent demonstrates that data can be sustained on open web platforms for nearly a year, with about 40% of replicas remaining after deployment, highlighting a real security threat to operators of such sites. The work underscores the need for mitigations (e.g., CAPTCHA, site lockdown) and discusses potential adaptations, including botnet-like data storage applications, while suggesting Graffiti Networks could complement existing P2P ecosystems rather than supplant them.

Abstract

The proliferation of peer-to-peer (P2P) file sharing protocols is due to their efficient and scalable methods for data dissemination to numerous users. But many of these networks have no provisions to provide users with long term access to files after the initial interest has diminished, nor are they able to guarantee protection for users from malicious clients that wish to implicate them in incriminating activities. As such, users may turn to supplementary measures for storing and transferring data in P2P systems. We present a new file sharing paradigm, called a Graffiti Network, which allows peers to harness the potentially unlimited storage of the Internet as a third-party intermediary. Our key contributions in this paper are (1) an overview of a distributed system based on this new threat model and (2) a measurement of its viability through a one-year deployment study using a popular web-publishing platform. The results of this experiment motivate a discussion about the challenges of mitigating this type of file sharing in a hostile network environment and how web site operators can protect their resources.

Paper Structure

This paper contains 19 sections, 4 figures, 1 table.

Table of Contents

  1. Introduction
  2. Related Work
  3. BitTorrent
  4. Peer-to-Peer Storage Systems
  5. Steganographic Storage Systems
  6. Alternative Storage Sites
  7. Graffiti Network Model
  8. Central Tracker
  9. Client
  10. Storage Sites
  11. Experimental Deployment
  12. Storage Site Discovery
  13. System Configuration
  14. Results
  15. Discussion
  16. ...and 4 more sections

Figures (4)

  • Figure 1: For a given a fileset, the client communicates with the tracker in the following manner: (1) the client sends the tracker the list of pieces it already has; (2) the tracker responds a list of instructions on where the client should download a sub-piece and the location of where to upload a replica; (3) after downloading the new sub-piece, the client then navigates the target storage site and uploads a new encrypted and encoded sub-piece payload; (4) the storage site returns an HTML page and the client verifies that the upload was successful. This process repeats until the client has all the pieces of the fileset and has produced enough replicas for the tracker.
  • Figure 2: Percentage of total replicas removed over time categorized by the type of failure.
  • Figure 3: The availability of replicas categorized by its corresponding storage site's protection schemes.
  • Figure 4: The cumulative availability of replicas categorized by their domain type: .com (42.5%), .edu (3.2%), .org (24.1%), US-based other (14.0%), and Non-US-based other (16.1%).