After presenting our work at Real World Crypto 2018 [1] and seeing the enormous press coverage, we want to get two things straight: 1. Most described weaknesses are only exploitable by the malicious server or by knowing a large secret number and thereby the protocols are still very secure (what we wrote in the paper but some newspapers did not adopt) and 2. we see ways to enhance the WhatsApp protocol without breaking its features.
We are of course very happy that our research reached so many people and even though IT security and cryptography are often hard to understand for outsiders, Andy Greenberg [2], Patrick Beuth [3] and other journalists [4,5,6,7,8] wrote articles that were understandable on the one hand and very accurate and precise on the other hand. In contrast to this, we also saw some inaccurate articles [9,10] that fanned fear and greatly diverged in their description from what we wrote in our paper. We expected this from the boulevard press in Germany and therefore asked them to stick to the facts when they were contacting us. But none of the worst two articles' [9,10] authors contacted us in advance. Since our aim was never to blame any application or protocol but rather we wanted to encourage the developers to enhance the protocols, it contradicts our aim that WhatsApp and Signal are partially declared attackable by "anyone" "easily" [9,10].
Against this background, we understand Moxie's vexation about certain headlines that were on the Internet in the last days [11]. However, we believe that the ones who understand the weaknesses, comprehend that only the malicious server can detectably make use of them (in WhatsApp) or the secret group ID needs to be obtained from a member (in Signal). As such, we want to make clear that our paper does not primarily focus on the description of weaknesses but presents a new approach for analyzing and evaluating the security of group instant messaging protocols. Further we propose measures to enhance the analyzed protocols. The description of the protocols' weaknesses is only one part of the evaluation of our analysis approach and thereby of the investigation of real world protocols. This is the scientific contribution of our paper. The practical contribution of the analyzed messengers, which is the communication confidentiality for billion users (in most cases), is great and should be noted. Therefore we believe that being Signal, WhatsApp, or Threema by applying encryption to all messages and consequently risking research with negative results is much better than being a messenger that does not encrypt group messages end-to-end at all. We do not want to blame messengers that are far less secure (read Moxie's post [11] if you are interested).
Finally we want note that applying security measures according to the ticket approach (as we call it in the paper [12]) to the invitation links would solve the issues that Facebook's security head mentioned in his reply [13] on our findings. To our knowledge, adding authenticity to group update messages would not affect invitation links: If no invitation link was generated for a group, group members should only accept joining users if they were added by an authentic group update message. As soon as a group invitation link was generated, all joining users would need to be accepted as new group members with the current design. However there are plenty ways how WhatsApp could use invitation links without endowing the server with the power to manage groups without the group admins' permission:
One approach would be generating the invitation links secretly and sharing them without the knowledge of the server. An invitation link could then contain a secret ticket for the group and the ID of the group. As soon as a user, who received the link, wants to join the group, she can request the server with the group ID to obtain all current group members. The secret ticket can now be sent to all existing group members encrypted such that the legitimate join can be verified.
Of course this would require engineering but the capability of WhatsApp, shipping drastic protocol updates, can be assumed since they applied end-to-end encryption in the first place.
[1] https://www.youtube.com/watch?v=i5i38WlHfds
[2] https://www.wired.com/story/whatsapp-security-flaws-encryption-group-chats/
[3] http://www.spiegel.de/netzwelt/apps/whatsapp-gruppenchats-schwachstelle-im-verschluesselungs-protokoll-a-1187338.html
[4] http://www.sueddeutsche.de/digital/it-sicherheit-wie-fremde-sich-in-whatsapp-gruppenchats-einladen-koennen-1.3821656
[5] https://techcrunch.com/2018/01/10/security-researchers-flag-invite-bug-in-whatsapp-group-chats/
[6] http://www.telegraph.co.uk/technology/2018/01/10/whatsapp-bug-raises-questions-group-message-privacy/
[7] http://www.handelsblatt.com/technik/it-internet/verschluesselung-umgangen-forscher-finden-sicherheitsluecke-bei-whatsapp/20836518.html
[8] https://www.heise.de/security/meldung/WhatsApp-und-Signal-Forscher-beschreiben-Schwaechen-verschluesselter-Gruppenchats-3942046.html
[9] https://www.theinquirer.net/inquirer/news/3024215/whatsapp-bug-lets-anyone-easily-infiltrate-private-group-chats
[10] http://www.dailymail.co.uk/sciencetech/article-5257713/WhatsApp-security-flaw-lets-spy-private-chats.html
[11] https://news.ycombinator.com/item?id=16117487
[12] https://eprint.iacr.org/2017/713.pdf
[13] https://twitter.com/alexstamos/status/951169036947107840
Further articles:
- Matthew Green's blog post: https://blog.cryptographyengineering.com/2018/01/10/attack-of-the-week-group-messaging-in-whatsapp-and-signal/
- Schneier on Security: https://www.schneier.com/blog/archives/2018/01/whatsapp_vulner.html
- Bild: http://www.bild.de/digital/smartphone-und-tablet/whatsapp/whatsapp-sicherheitsluecke-in-gruppenchats-54452080.bild.html
- Sun: https://www.thesun.co.uk/tech/5316110/new-whatsapp-bug-how-to-stay-safe/
We are of course very happy that our research reached so many people and even though IT security and cryptography are often hard to understand for outsiders, Andy Greenberg [2], Patrick Beuth [3] and other journalists [4,5,6,7,8] wrote articles that were understandable on the one hand and very accurate and precise on the other hand. In contrast to this, we also saw some inaccurate articles [9,10] that fanned fear and greatly diverged in their description from what we wrote in our paper. We expected this from the boulevard press in Germany and therefore asked them to stick to the facts when they were contacting us. But none of the worst two articles' [9,10] authors contacted us in advance. Since our aim was never to blame any application or protocol but rather we wanted to encourage the developers to enhance the protocols, it contradicts our aim that WhatsApp and Signal are partially declared attackable by "anyone" "easily" [9,10].
Against this background, we understand Moxie's vexation about certain headlines that were on the Internet in the last days [11]. However, we believe that the ones who understand the weaknesses, comprehend that only the malicious server can detectably make use of them (in WhatsApp) or the secret group ID needs to be obtained from a member (in Signal). As such, we want to make clear that our paper does not primarily focus on the description of weaknesses but presents a new approach for analyzing and evaluating the security of group instant messaging protocols. Further we propose measures to enhance the analyzed protocols. The description of the protocols' weaknesses is only one part of the evaluation of our analysis approach and thereby of the investigation of real world protocols. This is the scientific contribution of our paper. The practical contribution of the analyzed messengers, which is the communication confidentiality for billion users (in most cases), is great and should be noted. Therefore we believe that being Signal, WhatsApp, or Threema by applying encryption to all messages and consequently risking research with negative results is much better than being a messenger that does not encrypt group messages end-to-end at all. We do not want to blame messengers that are far less secure (read Moxie's post [11] if you are interested).
Finally we want note that applying security measures according to the ticket approach (as we call it in the paper [12]) to the invitation links would solve the issues that Facebook's security head mentioned in his reply [13] on our findings. To our knowledge, adding authenticity to group update messages would not affect invitation links: If no invitation link was generated for a group, group members should only accept joining users if they were added by an authentic group update message. As soon as a group invitation link was generated, all joining users would need to be accepted as new group members with the current design. However there are plenty ways how WhatsApp could use invitation links without endowing the server with the power to manage groups without the group admins' permission:
One approach would be generating the invitation links secretly and sharing them without the knowledge of the server. An invitation link could then contain a secret ticket for the group and the ID of the group. As soon as a user, who received the link, wants to join the group, she can request the server with the group ID to obtain all current group members. The secret ticket can now be sent to all existing group members encrypted such that the legitimate join can be verified.
Of course this would require engineering but the capability of WhatsApp, shipping drastic protocol updates, can be assumed since they applied end-to-end encryption in the first place.
[1] https://www.youtube.com/watch?v=i5i38WlHfds
[2] https://www.wired.com/story/whatsapp-security-flaws-encryption-group-chats/
[3] http://www.spiegel.de/netzwelt/apps/whatsapp-gruppenchats-schwachstelle-im-verschluesselungs-protokoll-a-1187338.html
[4] http://www.sueddeutsche.de/digital/it-sicherheit-wie-fremde-sich-in-whatsapp-gruppenchats-einladen-koennen-1.3821656
[5] https://techcrunch.com/2018/01/10/security-researchers-flag-invite-bug-in-whatsapp-group-chats/
[6] http://www.telegraph.co.uk/technology/2018/01/10/whatsapp-bug-raises-questions-group-message-privacy/
[7] http://www.handelsblatt.com/technik/it-internet/verschluesselung-umgangen-forscher-finden-sicherheitsluecke-bei-whatsapp/20836518.html
[8] https://www.heise.de/security/meldung/WhatsApp-und-Signal-Forscher-beschreiben-Schwaechen-verschluesselter-Gruppenchats-3942046.html
[9] https://www.theinquirer.net/inquirer/news/3024215/whatsapp-bug-lets-anyone-easily-infiltrate-private-group-chats
[10] http://www.dailymail.co.uk/sciencetech/article-5257713/WhatsApp-security-flaw-lets-spy-private-chats.html
[11] https://news.ycombinator.com/item?id=16117487
[12] https://eprint.iacr.org/2017/713.pdf
[13] https://twitter.com/alexstamos/status/951169036947107840
Further articles:
- Matthew Green's blog post: https://blog.cryptographyengineering.com/2018/01/10/attack-of-the-week-group-messaging-in-whatsapp-and-signal/
- Schneier on Security: https://www.schneier.com/blog/archives/2018/01/whatsapp_vulner.html
- Bild: http://www.bild.de/digital/smartphone-und-tablet/whatsapp/whatsapp-sicherheitsluecke-in-gruppenchats-54452080.bild.html
- Sun: https://www.thesun.co.uk/tech/5316110/new-whatsapp-bug-how-to-stay-safe/
More information
- Hacking Apps
- Ethical Hacker Tools
- Hacker Tools 2020
- Hack Website Online Tool
- Install Pentest Tools Ubuntu
- Pentest Tools Kali Linux
- Pentest Tools Review
- How To Hack
- Hack Tools Download
- Hack Tools Online
- Hacker Tools Hardware
- New Hack Tools
- Hack Tools 2019
- Computer Hacker
- Hack And Tools
- Hacking Tools For Beginners
- Hack App
- Hack Website Online Tool
- Pentest Tools
- Hacker Tools Mac
- Pentest Tools Free
- Pentest Box Tools Download
- Hacker Tools For Ios
- Hacking Tools For Games
- Hack Tool Apk No Root
- Hacking Tools For Windows
- Computer Hacker
- Pentest Tools Review
- Pentest Tools Tcp Port Scanner
- Growth Hacker Tools
- Hacking Apps
- Pentest Tools Framework
- Game Hacking
- Hacker Tools
- Hacking Tools For Mac
- Hack Tools Online
- Hacking Tools Free Download
- Hack Tools For Pc
- Hacker Tools For Ios
- Pentest Recon Tools
- Hack Tools For Mac
- Pentest Tools Windows
- Pentest Tools Review
- Hacking Tools For Kali Linux
- How To Make Hacking Tools
- Hacking Tools For Mac
- Hacking Tools Online
- Free Pentest Tools For Windows
- Pentest Tools Apk
- Hack Tools
- Hack Apps
- Hacking Tools Github
- Pentest Tools Tcp Port Scanner
- Install Pentest Tools Ubuntu
- Hacker Techniques Tools And Incident Handling
- Usb Pentest Tools
- Hacking Tools And Software
- Hacking Tools Software
- Pentest Tools For Android
- Growth Hacker Tools
- Hacker Tools Linux
- Hack Tool Apk
- Hacking Tools For Beginners
- Hacker Tools Apk Download
- How To Hack
- Pentest Recon Tools
- Hacking Tools Mac
- How To Hack
- Hack Tools Github
- Pentest Tools Kali Linux
- Hacking Tools Usb
- Hacker Tools Online
- Hacking Tools For Windows 7
- Computer Hacker
- Pentest Tools Find Subdomains
- Pentest Tools Alternative
- Best Pentesting Tools 2018
- Pentest Tools Free
- Physical Pentest Tools
- Nsa Hack Tools Download
- Hacking Tools Online
- Install Pentest Tools Ubuntu
- Hacker Tools For Windows
- Hack Tools
- Hacking Tools 2019
- Pentest Tools Apk
- Github Hacking Tools
- Pentest Tools Free
- Hacking Tools For Windows
- Pentest Tools Url Fuzzer
- Blackhat Hacker Tools
- Pentest Tools Download
- Hack Tools Pc
- Hack App
- Hacker Tools Free Download
- Hacking Tools For Games
- Hack Tools For Windows
- Hacking Tools Free Download
- Physical Pentest Tools
- Ethical Hacker Tools
- Hack Tools
- Hacking Tools For Windows Free Download
- Hacking Tools For Mac
- Hacker Tools Linux
- Tools For Hacker
- Hacker Tools Linux
- Hacking Tools 2019
- Hacking Tools For Windows 7
- Hacker Tools Apk
- Hack Website Online Tool
- Kik Hack Tools
- Pentest Tools Android
- Hacker Tools 2020
- Hack Tools Pc
- Hacker Tool Kit
- Hack Tools Download
- Hacking Tools Online
- Hacking Tools Windows 10
- Hacker Tools 2019
- Hack Website Online Tool
- Pentest Tools For Windows
- Hack Tools 2019
- Hacker Tools Online
- Hack Tools For Pc
- Pentest Tools Nmap
- Game Hacking
- Hack Tools
- Pentest Tools For Mac
- Hack Tools For Pc
- Pentest Tools Website
- Tools Used For Hacking
- Hack Tools Download
- Hack Tools Online
- Hacking Tools Usb
- Pentest Tools Website
- Hack Tools Online
- Pentest Tools Find Subdomains
- Pentest Tools Tcp Port Scanner
- Pentest Tools List
- Pentest Tools Review
- Hack Tool Apk
- Hacker Tools Windows
- Nsa Hack Tools
- Hack Tools For Mac
- Hacking Tools 2020
- Pentest Tools Download
- Tools For Hacker
- Pentest Tools Alternative
- Install Pentest Tools Ubuntu
- Hacker Tools Hardware
- Hackrf Tools
- Hack Apps
- Hacker Tools Apk Download
- Hacking Tools Mac
- Best Hacking Tools 2020
- Pentest Tools Apk
No comments:
Post a Comment