Reception and criticism of WhatsApp security and privacy features

On May 20, 2011, an unconfirmed security researcher from the Netherlands under the pseudonym "WhatsappHack" published, to the Dutch websites Tweakers.net and GeenStijl, a method by which WhatsApp accounts could be hijacked. The researcher noticed a flaw in the authentication process, which allowed the researcher to hijack an account by trying to login with another phone number and intercepting the verification SMS text message that, under specific conditions, remained in the outbox of the Symbian phone after the WhatsApp client would attempt to send it to itself. On Android, the verification message could be obtained through reading the "radio" with a tool named "logcat". The researcher would then copy and send the intercepted verification message to the real number of the phone, using an SMS gateway to spoof the "sender" phone number to the number the researcher tried to maliciously login with. This method worked, and WhatsApp issued a patch within one day after publication of the articles, to both the Android and Symbian clients. WhatsApp did have a security mechanism, by design, which would disable the account on the phone of the original owner of the phone number, when they had a WhatsApp account.[34][35][36]

In May 2011, another security hole was reported which left communication through WhatsApp susceptible to packet analysis. WhatsApp communications were not encrypted, and data was sent and received in plaintext, meaning messages could easily be read if packet traces were available.[37]

In May 2012 security researchers noticed that new updates of WhatsApp no longer sent messages as plaintext,[38][39][40] but the cryptographic method implemented was subsequently described as "broken".[41][42] In August 2012 the WhatsApp support staff said that messages were encrypted in the "latest version" of the WhatsApp software for iOS and Android (but not BlackBerry, Windows Phone, and Symbian), without specifying the cryptographic method.[43]

On January 6, 2012, an unknown hacker published a website that made it possible to change the status of an arbitrary WhatsApp user, as long as the phone number was known. To make it work, it only required a restart of the app. According to the hacker, it was only one of many security problems in WhatsApp. On January 9, WhatsApp reported that it had resolved the problem, although the only measure actually taken was to block the website's IP address. As a reaction, a Windows tool was made available for download providing the same functionality. This problem has since been resolved in the form of an IP address check on currently logged-in sessions.[44][45]

German Tech site The H demonstrated how to use WhatsAPI to hijack any WhatsApp account on September 14, 2012.[46] Shortly after, a legal threat to WhatsAPI's developers was alleged, characterized by The H as "an apparent reaction" to security reports, and WhatsAPI's source code was taken down for some days.[47] The WhatsAPI team has since returned to active development.[48]

On March 31, 2013 the Saudi Arabian Communications and Information Technology Commission (CITC) issued a statement regarding possible measures against WhatsApp, among other applications, unless the service providers took serious steps to comply with monitoring and privacy regulations.[49]

In February 2014, the public authority for data privacy of the German state of Schleswig-Holstein advised against using WhatsApp, as the service lacked privacy protection such as end-to-end client side encryption technology.[50] WhatsApp started implementing end-to-end encryption in late 2014 and finished in April 2016.[28]

A major privacy and security problem has been the subject of a joint Canadian-Dutch government investigation. The primary concern was that WhatsApp required users to upload their mobile phone's entire address book to WhatsApp servers so that WhatsApp could discover who, among the users' contacts, was available via WhatsApp. While this was a fast and convenient way to quickly find and connect the user with contacts who were also using WhatsApp, it meant that their address book was then mirrored on the WhatsApp servers, including contact information for contacts who were not using WhatsApp. This information, which consisted solely of phone numbers without any additional information such as the name of the contact, was stored in hashed, though not salted, form.[51][52][53][54] Late 2015, the Dutch government released a press-statement claiming that WhatsApp had changed its hashing method, making it much harder to reverse, and thus now fully complies with all rules and regulations.[55]

A user does not need to send a friend request to send messages to another user, due to the contact discovery mentioned above.[56]

In November 2014, WhatsApp introduced a feature named Read Receipts which alerts senders when their messages are read by recipients. Within a week, WhatsApp introduced an update allowing users to disable this feature so that message recipients do not send acknowledgements.[57] On December 1, 2014, Indrajeet Bhuyan and Saurav Kar, both 17 years old, demonstrated the WhatsApp Message Handler Vulnerability, which allows anyone to remotely crash WhatsApp just by sending a specially crafted message of 2kb in size. To escape the problem, the user who receives the specially crafted message has to delete his/her whole conversation and start a fresh chat, because opening the message keeps on crashing WhatsApp unless the chat is deleted completely.[58] In early 2015, after WhatsApp launched a web client that can be used from the browser, Bhuyan also found that it had two security issues that compromised user privacy: the WhatsApp Photo Privacy Bug and the WhatsApp Web Photo Sync Bug.[59][60]

In February 2015, a Dutch university student named Maikel Zweerink published an app that set out to prove that anyone could track a WhatsApp user's status and also keep an eye of their changing profile pictures, privacy settings or status messages regardless of their privacy settings.[61]

On March 2, 2016, WhatsApp introduced its document-sharing feature, initially allowing users to share PDF files with their contacts.[62] However, WhatsApp's default state of automatically downloading attachments raised some concerns in the press about risk and security once support for document sharing expanded beyond PDF files.[63]

In August 2016, WhatsApp announced that it will start sharing account information with Facebook, consisting of the phone number of the account owner and aggregated analytical data. The address books and metadata of users are not shared. According to WhatsApp, this account information is shared to "track basic metrics about how often people use our services and better fight spam on WhatsApp. And by connecting your phone number with Facebook's systems, Facebook can offer better friend suggestions and show you more relevant ads if you have an account with them." This means that Facebook can target advertisements on the Facebook Platform better by making links between users based on the phone numbers, and make "friend suggestions" to its users based on WhatsApp's data. User data will not be shared with advertisers, and is only used internally on the Facebook services. WhatsApp emphasizes the content of user messages is still kept private thanks to its end-to-end encryption, which means WhatsApp cannot read the content of chats.[64][65] However, users are given the choice to opt out of sharing this data with Facebook for advertisement purposes.[66] In October 2016, Article 29 Working Party stated that it has serious concerns regarding the manner in which the information relating to the updated Terms of Service and Privacy Policy was provided to users and consequently about the validity of the users’ consent.[67]

From April 5, 2016, end-to-end encryption for all users' communications, including file transfers and voice calls, is supported for users of the latest client, encryption being enabled by default. It uses Curve25519 for key exchange, HKDF for generation of session keys (AES-256 in CBC mode for encryption and HMAC-SHA256 for integrity verification) and SHA512 for generating the two 30 digit fingerprints of both users' identity keys so they can verify each other as needed. Even the company would be unable to decrypt users' communications. Amnesty International and security professionals praised the move; the US Federal Bureau of Investigation criticised it as threatening the work of law enforcement.[68] Telegram, another messaging service, is reported by the BBC to be used by "Islamic State" extremists.[68]

WhatsApp is not the only messaging service that provides end-to-end encryption; among others, Threema, Wickr, Signal, Silent Phone, and Line also provide such encryption by default. iMessage and Viber provide it under special circumstances.[69][70] Telegram provides end-to-end encryption as an opt-in feature, but does not support end-to-end encrypted group messaging.[28]

As of April 5, 2016, WhatsApp has a score of 6 out of 7 points on the Electronic Frontier Foundation's "Secure Messaging Scorecard". It has received points for having communications encrypted in transit, having communications encrypted with keys the provider doesn't have access to, allowing users to verify contacts' identities, having past messages secure if the encryption keys are stolen, having completed a recent independent security audit, and having the security designs properly documented. It is missing a point because the code is not open to independent review.[71]

On January 13, 2017, The Guardian reported that security researcher Tobias Boelter had found that WhatsApp's policy of forcing re-encryption of initially undelivered messages, without informing the recipient, constituted a serious loophole whereby WhatsApp could disclose, or be compelled to disclose, the content of these messages.[72] WhatsApp[73] and Open Whisper Systems[74] officials disagreed with this assessment. A follow-up article by Boelter himself explained in greater detail what he considered to be the specific vulnerability. This article has since been removed[75] by The Guardian due to the inaccuracies in Boelter's representation of the facts. After complaints from 73 renowned security researchers,[76] The Guardian was forced to substantially revise and correct their own articles as well. Therefore, in June 2017, The Guardian readers’ editor Paul Chadwick wrote that "The Guardian was wrong to report in January that the popular messaging service WhatsApp had a security flaw so serious that it was a huge threat to freedom of speech."[77]

"In a detailed review I found that misinterpretations, mistakes and misunderstandings happened at several stages of the reporting and editing process. Cumulatively they produced an article that overstated its case."

— Paul Chadwick, The Guardian[77]

Chadwick also noted that since the Guardian article, WhatsApp has been "better secured by the introduction of optional two-factor verification in February."[77] However, it is important to note that this feature was already introduced in public beta versions of WhatsApp as early as November 2016,[78] which was months before The Guardian wrote about the alleged issue.

On January 15, 2017, a research team from Ruhr University Bochum published a security analysis of group messaging protocols in WhatsApp, Signal, and Threema. Among other deficiencies, they found out that WhatsApp's servers effectively control the membership in groups. Consequently, the server can add arbitrary other phone numbers to groups (including itself) such that future communication becomes insecure. Even though such manipulations could be detected, it weakens the end-to-end security guarantees.[79]

In October 2017, the German software company Open-Xchange criticised WhatsApp and Slack for using proprietary software and stated plans to create an open source alternative.[80]

In May 2019, it was revealed that there was a security vulnerability in WhatsApp, allowing a remote person to install a spyware just by making a call which does not even need to be answered.[81] Later, in June 2019, another vulnerability was revealed, allowing a user to transform an audio call into a video call, without the victim consent and without the victim noticing. A bug bounty of 5000 USD was offered for this bug.[82]

In December 2019, WhatsApp confirmed a security flaw that would allow hackers to use a malicious GIF image file to gain access to the recipient's data. The flaw was first reported by a user named Awakened on GitHub with an explanation of how the exploit worked. When the recipient opened the gallery within WhatsApp, even if not sending the malicious image, the hack is triggered and the device and its contents become vulnerable. The flaw was patched and users were encouraged to update WhatsApp.[83][84][85]

In June 2019, WhatsApp announced that it would take legal action against users who send disproportionately high number of messages using their communication platform. The company reiterated that its platform was meant for private messaging or for businesses to interact with their customers through their business app. In a notification on their website the company stated "Beginning on December 7, 2019, WhatsApp will take legal action against those we determine are engaged in or assisting others in abuse that violates our terms of service, such as automated or bulk messaging".[86]

In September 2019, WhatsApp was criticized for its implementation of a 'delete for everyone' feature. iOS users can elect to save media to their camera roll automatically. When a user deletes media for everyone, WhatsApp does not delete images saved in the iOS camera roll and so those users are able to keep the images. WhatsApp released a statement saying that "the feature is working properly," and that images stored in the camera roll cannot be deleted due to Apple's security layers.[87]

In December 2019, WhatsApp confirmed a security flaw that would allow hackers to use a malicious GIF image file to gain access to the recipient's data. When the recipient opened the gallery within WhatsApp, even if not sending the malicious image, the hack is triggered and the device and its contents become vulnerable. The flaw was patched and users were encouraged to update WhatsApp.[88][89][90]

In November 2019, WhatsApp released a new privacy feature that let users decide who adds them to the group.[91]

On December 17, 2019, WhatsApp fixed a security flaw that allowed cyber attackers to repeatedly crash the messaging application for all members of group chat, which could only be fixed by forcing the complete uninstall and reinstall of the app.[92] The bug was discovered by Check Point in August 2019 and reported to WhatsApp. It was fixed in version 2.19.246 onwards.[93][94]

For security purposes, since February 1, 2020, WhatsApp has been made unavailable on smartphones using legacy operating systems like Android 2.3.7 or older and iPhone iOS 8 or older that are no longer updated by their providers.[95]

In April 2020, the NSO Group held its governmental clients accountable for the allegation of human rights abuses by WhatsApp. In its revelation via documents received from court, the group claimed that the lawsuit brought against the company by WhatsApp threatened to infringe on its clients’ “national security and foreign policy concerns”. However, the company did not reveal names of the end users, which according to a research by Citizen Lab include, Saudi Arabia, Bahrain, Kazakhstan, Morocco, Mexico and the United Arab Emirates.[96]

On 16 December 2020, a claim that WhatsApp gave Google access to private messages was included in the anti-trust case against the latter. As the complaint is heavily redacted due to being an ongoing case, it doesn't disclose whether this alleges tampering with the app's end-to-end encryption or simply Google accessing user backups.[97]

In January 2021, WhatsApp announced update to Privacy Policy which states that WhatsApp will collect the meta data of users and share it with Facebook and its "family of companies" starting February 2021.[98] Previously, users could opt-out of such data sharing, but the new policy removes this option. The new Privacy Policy is said not apply fully within EU, because of the GDPR. The new Privacy Policy for European Region, however, explicitly states that as part of the Facebook Companies WhatsApp shares information with, the other Facebook Companies.[99] Facebook and Whatsapp has been widely criticised for this move.[100]

Facing a pushback about Facebook data sharing and lack of clarity, WhatsApp postponed the implementation of the privacy policy update scheduled from February 8 2021 to May 15 2021.[101][102]

2020