---
_id: '58801'
abstract:
- lang: eng
  text: Iran employs one of the most prominent Internet censors in the world. An important
    part of Iran’s censorship apparatus is its analysis of unencrypted protocols such
    as HTTP and DNS. During routine evaluations of Iran’s HTTP and DNS censorship,
    we noticed several properties we believe to be unknown today. For instance, we
    found injections of correct static IPs for some domains such as google.com on
    the DNS level, unclear HTTP version parsing, and correlations between DNS and
    HTTP censorship. In this paper, we present our findings to the community and discuss
    possible takeaways for affected people and the censorship circumvention community.
    As some of our findings left us bewildered, we hope to ignite a discussion about
    Iran’s censorship behavior. We aim to use the discussion of our work to execute
    a thorough analysis and explanation of Iran’s censorship behavior in the future.
author:
- first_name: Felix
  full_name: Lange, Felix
  id: '67893'
  last_name: Lange
- first_name: Niklas
  full_name: Niere, Niklas
  id: '63563'
  last_name: Niere
- first_name: Jonathan
  full_name: von Niessen, Jonathan
  last_name: von Niessen
- first_name: Dennis
  full_name: Suermann, Dennis
  last_name: Suermann
- first_name: Nico
  full_name: Heitmann, Nico
  id: '74619'
  last_name: Heitmann
  orcid: 0009-0003-7687-7044
- first_name: Juraj
  full_name: Somorovsky, Juraj
  id: '83504'
  last_name: Somorovsky
  orcid: 0000-0002-3593-7720
citation:
  ama: 'Lange F, Niere N, von Niessen J, Suermann D, Heitmann N, Somorovsky J. I(ra)nconsistencies:
    Novel Insights into Iran’s Censorship. In: <i>Proceedings on Privacy Enhancing
    Technologies</i>. ; 2025.'
  apa: 'Lange, F., Niere, N., von Niessen, J., Suermann, D., Heitmann, N., &#38; Somorovsky,
    J. (2025). I(ra)nconsistencies: Novel Insights into Iran’s Censorship. <i>Proceedings
    on Privacy Enhancing Technologies</i>. Free and Open Communications on the Internet,
    Virtual.'
  bibtex: '@inproceedings{Lange_Niere_von Niessen_Suermann_Heitmann_Somorovsky_2025,
    title={I(ra)nconsistencies: Novel Insights into Iran’s Censorship}, booktitle={Proceedings
    on Privacy Enhancing Technologies}, author={Lange, Felix and Niere, Niklas and
    von Niessen, Jonathan and Suermann, Dennis and Heitmann, Nico and Somorovsky,
    Juraj}, year={2025} }'
  chicago: 'Lange, Felix, Niklas Niere, Jonathan von Niessen, Dennis Suermann, Nico
    Heitmann, and Juraj Somorovsky. “I(Ra)Nconsistencies: Novel Insights into Iran’s
    Censorship.” In <i>Proceedings on Privacy Enhancing Technologies</i>, 2025.'
  ieee: 'F. Lange, N. Niere, J. von Niessen, D. Suermann, N. Heitmann, and J. Somorovsky,
    “I(ra)nconsistencies: Novel Insights into Iran’s Censorship,” presented at the
    Free and Open Communications on the Internet, Virtual, 2025.'
  mla: 'Lange, Felix, et al. “I(Ra)Nconsistencies: Novel Insights into Iran’s Censorship.”
    <i>Proceedings on Privacy Enhancing Technologies</i>, 2025.'
  short: 'F. Lange, N. Niere, J. von Niessen, D. Suermann, N. Heitmann, J. Somorovsky,
    in: Proceedings on Privacy Enhancing Technologies, 2025.'
conference:
  end_date: 2025-02-20
  location: Virtual
  name: Free and Open Communications on the Internet
  start_date: 2025-02-20
date_created: 2025-02-24T08:09:56Z
date_updated: 2025-05-06T13:48:32Z
ddc:
- '006'
department:
- _id: '632'
file:
- access_level: closed
  content_type: application/pdf
  creator: flange
  date_created: 2025-02-24T08:07:59Z
  date_updated: 2025-02-24T08:07:59Z
  file_id: '58802'
  file_name: foci-2025-0002.pdf
  file_size: 535700
  relation: main_file
  success: 1
file_date_updated: 2025-02-24T08:07:59Z
has_accepted_license: '1'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://www.petsymposium.org/foci/2025/foci-2025-0002.pdf
oa: '1'
publication: Proceedings on Privacy Enhancing Technologies
quality_controlled: '1'
status: public
title: 'I(ra)nconsistencies: Novel Insights into Iran’s Censorship'
type: conference
user_id: '63563'
year: '2025'
...
---
_id: '60503'
abstract:
- lang: eng
  text: 'Censors have long censored Transport Layer Security (TLS) traffic by inspecting
    the domain name in the unencrypted Server Name Indication (SNI) extension. By
    encrypting the SNI extension, the Encrypted ClientHello (ECH) prevents censors
    from blocking TLS traffic to certain domains. Despite this promising outlook,
    ECH’s current capability to contest TLS censorship is unclear; for instance, Russia
    has started censoring ECH connections successfully. This paper clarifies ECH’s
    current role for TLS censorship. To this end, we evaluate servers’ support for
    ECH and its analysis and subsequent blocking by censors. We determine Cloudflare
    as the only major provider supporting ECH. Additionally, we affirm previously
    known ECH censorship in Russia and uncover indirect censorship of ECH through
    encrypted DNS censorship in China and Iran. Our findings suggest that ECH’s contribution
    to censorship circumvention is currently limited: we consider ECH’s dependence
    on encrypted DNS especially challenging for ECH’s capability to circumvent censorship.
    We stress the importance of censorship-resistant ECH to solve the long-known problem
    of SNI-based TLS censorship.'
author:
- first_name: Niklas
  full_name: Niere, Niklas
  id: '63563'
  last_name: Niere
- first_name: Felix
  full_name: Lange, Felix
  id: '67893'
  last_name: Lange
- first_name: Nico
  full_name: Heitmann, Nico
  id: '74619'
  last_name: Heitmann
  orcid: 0009-0003-7687-7044
- first_name: Juraj
  full_name: Somorovsky, Juraj
  id: '83504'
  last_name: Somorovsky
  orcid: 0000-0002-3593-7720
citation:
  ama: 'Niere N, Lange F, Heitmann N, Somorovsky J. Encrypted Client Hello (ECH) in
    Censorship Circumvention. In: ; 2025.'
  apa: Niere, N., Lange, F., Heitmann, N., &#38; Somorovsky, J. (2025). <i>Encrypted
    Client Hello (ECH) in Censorship Circumvention</i>. Free and Open Communications
    on the Internet, Washington, D.C.
  bibtex: '@inproceedings{Niere_Lange_Heitmann_Somorovsky_2025, title={Encrypted Client
    Hello (ECH) in Censorship Circumvention}, author={Niere, Niklas and Lange, Felix
    and Heitmann, Nico and Somorovsky, Juraj}, year={2025} }'
  chicago: Niere, Niklas, Felix Lange, Nico Heitmann, and Juraj Somorovsky. “Encrypted
    Client Hello (ECH) in Censorship Circumvention,” 2025.
  ieee: N. Niere, F. Lange, N. Heitmann, and J. Somorovsky, “Encrypted Client Hello
    (ECH) in Censorship Circumvention,” presented at the Free and Open Communications
    on the Internet, Washington, D.C., 2025.
  mla: Niere, Niklas, et al. <i>Encrypted Client Hello (ECH) in Censorship Circumvention</i>.
    2025.
  short: 'N. Niere, F. Lange, N. Heitmann, J. Somorovsky, in: 2025.'
conference:
  end_date: 2025-07-14
  location: Washington, D.C.
  name: Free and Open Communications on the Internet
  start_date: 2025-07-14
date_created: 2025-07-03T07:14:00Z
date_updated: 2025-10-23T14:26:38Z
ddc:
- '006'
file:
- access_level: open_access
  content_type: application/pdf
  creator: nniklas
  date_created: 2025-07-03T07:11:14Z
  date_updated: 2025-10-23T14:26:38Z
  file_id: '60505'
  file_name: foci-2025-0016.pdf
  file_size: 755171
  relation: main_file
file_date_updated: 2025-10-23T14:26:38Z
has_accepted_license: '1'
keyword:
- censorship
- circumvention
- ECH
- TLS
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://www.petsymposium.org/foci/2025/foci-2025-0016.pdf
oa: '1'
status: public
title: Encrypted Client Hello (ECH) in Censorship Circumvention
type: conference
user_id: '63563'
year: '2025'
...
---
_id: '54437'
abstract:
- lang: eng
  text: "Video conferencing systems have become an indispensable part of our world.
    Using video conferencing systems implies the expectation that online meetings
    run as smoothly as in-person meetings. Thus, online meetings need to be just as
    secure and private as in-person meetings, which are secured against disruptive
    factors and unauthorized persons by physical access control mechanisms.\r\n\r\nTo
    show the security dangers of conferencing systems and raise general awareness
    when using these technologies, we analyze the security of two widely used research
    and education open-source video conferencing systems: BigBlueButton and eduMEET.
    Because both systems are very different, we analyzed their architectures, considering
    the respective components with their main tasks, features, and user roles. In
    the following systematic security analyses, we found 50 vulnerabilities. These
    include broken access control, NoSQL injection, and denial of service (DoS). The
    vulnerabilities have root causes of different natures. While BigBlueButton has
    a lot of complexity due to many components, eduMEET, which is relatively young,
    focuses more on features than security. The sheer amount of results and the lack
    of prior work indicate a research gap that needs to be closed since video conferencing
    systems continue to play a significant role in research, education, and everyday
    life."
author:
- first_name: Nico
  full_name: Heitmann, Nico
  id: '74619'
  last_name: Heitmann
- first_name: Hendrik
  full_name: Siewert, Hendrik
  last_name: Siewert
- first_name: Sven
  full_name: Moog, Sven
  last_name: Moog
- first_name: Juraj
  full_name: Somorovsky, Juraj
  id: '83504'
  last_name: Somorovsky
  orcid: 0000-0002-3593-7720
citation:
  ama: 'Heitmann N, Siewert H, Moog S, Somorovsky J. Security Analysis of BigBlueButton
    and eduMEET. In: <i>Applied Cryptography and Network Security</i>. Springer Nature
    Switzerland; 2024. doi:<a href="https://doi.org/10.1007/978-3-031-54776-8_8">10.1007/978-3-031-54776-8_8</a>'
  apa: Heitmann, N., Siewert, H., Moog, S., &#38; Somorovsky, J. (2024). Security
    Analysis of BigBlueButton and eduMEET. <i>Applied Cryptography and Network Security</i>.
    <a href="https://doi.org/10.1007/978-3-031-54776-8_8">https://doi.org/10.1007/978-3-031-54776-8_8</a>
  bibtex: '@inproceedings{Heitmann_Siewert_Moog_Somorovsky_2024, place={Cham}, title={Security
    Analysis of BigBlueButton and eduMEET}, DOI={<a href="https://doi.org/10.1007/978-3-031-54776-8_8">10.1007/978-3-031-54776-8_8</a>},
    booktitle={Applied Cryptography and Network Security}, publisher={Springer Nature
    Switzerland}, author={Heitmann, Nico and Siewert, Hendrik and Moog, Sven and Somorovsky,
    Juraj}, year={2024} }'
  chicago: 'Heitmann, Nico, Hendrik Siewert, Sven Moog, and Juraj Somorovsky. “Security
    Analysis of BigBlueButton and EduMEET.” In <i>Applied Cryptography and Network
    Security</i>. Cham: Springer Nature Switzerland, 2024. <a href="https://doi.org/10.1007/978-3-031-54776-8_8">https://doi.org/10.1007/978-3-031-54776-8_8</a>.'
  ieee: 'N. Heitmann, H. Siewert, S. Moog, and J. Somorovsky, “Security Analysis of BigBlueButton
    and eduMEET,” Abu Dhabi, 2024, doi: <a href="https://doi.org/10.1007/978-3-031-54776-8_8">10.1007/978-3-031-54776-8_8</a>.'
  mla: Heitmann, Nico, et al. “Security Analysis of BigBlueButton and EduMEET.” <i>Applied
    Cryptography and Network Security</i>, Springer Nature Switzerland, 2024, doi:<a
    href="https://doi.org/10.1007/978-3-031-54776-8_8">10.1007/978-3-031-54776-8_8</a>.
  short: 'N. Heitmann, H. Siewert, S. Moog, J. Somorovsky, in: Applied Cryptography
    and Network Security, Springer Nature Switzerland, Cham, 2024.'
conference:
  end_date: 2024-03-08
  location: Abu Dhabi
  start_date: 2024-03-05
date_created: 2024-05-23T11:15:39Z
date_updated: 2024-05-23T11:20:29Z
department:
- _id: '632'
doi: 10.1007/978-3-031-54776-8_8
language:
- iso: eng
main_file_link:
- url: https://link.springer.com/content/pdf/10.1007/978-3-031-54776-8_8.pdf
place: Cham
publication: Applied Cryptography and Network Security
publication_status: published
publisher: Springer Nature Switzerland
status: public
title: Security Analysis of BigBlueButton and eduMEET
type: conference
user_id: '74619'
year: '2024'
...
---
_id: '57816'
abstract:
- lang: eng
  text: "TLS-Attacker is an open-source framework for analyzing Transport\r\nLayer
    Security (TLS) implementations. The framework allows users\r\nto specify custom
    protocol flows and provides modification hooks to\r\nmanipulate message contents.
    Since its initial publication in 2016 by\r\nJuraj Somorovsky, TLS-Attacker has
    been used in numerous studies\r\npublished at well-established conferences and
    helped to identify\r\nvulnerabilities in well-known open-source TLS libraries.
    To enable\r\nautomated analyses, TLS-Attacker has grown into a suite of projects,\r\neach
    designed as a building block that can be applied to facilitate\r\nvarious analysis
    methodologies. The framework still undergoes\r\ncontinuous improvements with feature
    extensions, such as DTLS\r\n1.3 or the addition of new dialects such as QUIC,
    to continue its\r\neffectiveness and relevancy as a security analysis framework."
author:
- first_name: Fabian
  full_name: Bäumer, Fabian
  last_name: Bäumer
- first_name: Marcus
  full_name: Brinkmann, Marcus
  last_name: Brinkmann
- first_name: Nurullah
  full_name: Erinola, Nurullah
  last_name: Erinola
- first_name: Sven Niclas
  full_name: Hebrok, Sven Niclas
  id: '55616'
  last_name: Hebrok
  orcid: 0009-0006-1172-1665
- first_name: Nico
  full_name: Heitmann, Nico
  id: '74619'
  last_name: Heitmann
  orcid: 0009-0003-7687-7044
- first_name: Felix
  full_name: Lange, Felix
  id: '67893'
  last_name: Lange
- first_name: Marcel
  full_name: Maehren, Marcel
  last_name: Maehren
- first_name: Robert
  full_name: Merget, Robert
  last_name: Merget
- first_name: Niklas
  full_name: Niere, Niklas
  id: '63563'
  last_name: Niere
- first_name: Maximilian Manfred
  full_name: Radoy, Maximilian Manfred
  id: '68826'
  last_name: Radoy
  orcid: 0009-0005-3059-6823
- first_name: Conrad
  full_name: Schmidt, Conrad
  last_name: Schmidt
- first_name: Jörg
  full_name: Schwenk, Jörg
  last_name: Schwenk
- first_name: Juraj
  full_name: Somorovsky, Juraj
  id: '83504'
  last_name: Somorovsky
  orcid: 0000-0002-3593-7720
citation:
  ama: 'Bäumer F, Brinkmann M, Erinola N, et al. TLS-Attacker: A Dynamic Framework
    for Analyzing TLS Implementations. In: <i>Proceedings of Cybersecurity Artifacts
    Competition and Impact Award (ACSAC ’24)</i>. ; 2024.'
  apa: 'Bäumer, F., Brinkmann, M., Erinola, N., Hebrok, S. N., Heitmann, N., Lange,
    F., Maehren, M., Merget, R., Niere, N., Radoy, M. M., Schmidt, C., Schwenk, J.,
    &#38; Somorovsky, J. (2024). TLS-Attacker: A Dynamic Framework for Analyzing TLS
    Implementations. <i>Proceedings of Cybersecurity Artifacts Competition and Impact
    Award (ACSAC ’24)</i>. Annual Computer Security Applications Conference, Hawaii.'
  bibtex: '@inproceedings{Bäumer_Brinkmann_Erinola_Hebrok_Heitmann_Lange_Maehren_Merget_Niere_Radoy_et
    al._2024, title={TLS-Attacker: A Dynamic Framework for Analyzing TLS Implementations},
    booktitle={Proceedings of Cybersecurity Artifacts Competition and Impact Award
    (ACSAC ’24)}, author={Bäumer, Fabian and Brinkmann, Marcus and Erinola, Nurullah
    and Hebrok, Sven Niclas and Heitmann, Nico and Lange, Felix and Maehren, Marcel
    and Merget, Robert and Niere, Niklas and Radoy, Maximilian Manfred and et al.},
    year={2024} }'
  chicago: 'Bäumer, Fabian, Marcus Brinkmann, Nurullah Erinola, Sven Niclas Hebrok,
    Nico Heitmann, Felix Lange, Marcel Maehren, et al. “TLS-Attacker: A Dynamic Framework
    for Analyzing TLS Implementations.” In <i>Proceedings of Cybersecurity Artifacts
    Competition and Impact Award (ACSAC ’24)</i>, 2024.'
  ieee: 'F. Bäumer <i>et al.</i>, “TLS-Attacker: A Dynamic Framework for Analyzing
    TLS Implementations,” presented at the Annual Computer Security Applications Conference,
    Hawaii, 2024.'
  mla: 'Bäumer, Fabian, et al. “TLS-Attacker: A Dynamic Framework for Analyzing TLS
    Implementations.” <i>Proceedings of Cybersecurity Artifacts Competition and Impact
    Award (ACSAC ’24)</i>, 2024.'
  short: 'F. Bäumer, M. Brinkmann, N. Erinola, S.N. Hebrok, N. Heitmann, F. Lange,
    M. Maehren, R. Merget, N. Niere, M.M. Radoy, C. Schmidt, J. Schwenk, J. Somorovsky,
    in: Proceedings of Cybersecurity Artifacts Competition and Impact Award (ACSAC
    ’24), 2024.'
conference:
  end_date: 2024-12-13
  location: Hawaii
  name: Annual Computer Security Applications Conference
  start_date: 2024-12-09
date_created: 2024-12-17T11:25:14Z
date_updated: 2025-02-27T08:02:30Z
department:
- _id: '632'
keyword:
- SSL
- TLS
- DTLS
- Protocol State Fuzzing
- Planning Based
language:
- iso: eng
publication: Proceedings of Cybersecurity Artifacts Competition and Impact Award (ACSAC
  ’24)
quality_controlled: '1'
status: public
title: 'TLS-Attacker: A Dynamic Framework for Analyzing TLS Implementations'
type: conference
user_id: '67893'
year: '2024'
...