Therefore I reverse engineered two apps that are dating.

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Therefore I reverse engineered two apps that are dating.
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Video and picture drip through misconfigured S3 buckets

Typically for images or any other asserts, some sort of Access Control List (ACL) could be in position. A common way of implementing ACL would be for assets such as profile pictures

The main element would act as a “password” to get into the file, and also the password would simply be offered users who require usage of the image. When it comes to an app that is dating it’s going to be whoever the profile is presented to.

I’ve identified several misconfigured S3 buckets on The League throughout the research. All images and videos are inadvertently made general general public, with metadata such as which user uploaded them as soon as. Usually the application would have the pictures through Cloudfront, a CDN on top of this buckets that are s3. Unfortunately the underlying S3 buckets are severely misconfigured.

Side note: as much as i can inform, the profile UUID is arbitrarily created server-side as soon as the profile is established. In order that right part is not likely to be very easy to imagine. The filename is managed by the customer; the host takes any filename. In your client app it’s hardcoded to upload.jpg .

The seller has since disabled listObjects that are public. Nonetheless, we nevertheless think there must be some randomness into the key. A timestamp cannot act as key.

internet protocol address doxing through website website website link previews

Link preview is something this is certainly difficult to get appropriate in a complete large amount of messaging apps. You will find typically three techniques for website website link previews:

The League utilizes link that is recipient-side. Whenever an email includes a web link to a outside image, the hyperlink is fetched on user’s unit as soon as the message is seen. This will effortlessly enable a harmful transmitter to submit an external image URL pointing to an assailant managed host, obtaining recipient’s internet protocol address as soon as the message is exposed.

A significantly better solution may be merely to connect the image within the message when it’s delivered (sender-side preview), or have actually the server fetch the image and place it into the message (server-side preview). Server-side previews allows anti-abuse scanning that is additional. It may be a significantly better choice, but nevertheless maybe maybe not bulletproof.

Zero-click session hijacking through talk

The application will attach the authorization sometimes header to needs that do not need authentication, such as for instance Cloudfront GET demands. It will gladly hand out the bearer token in requests to domains that are external some situations.

Some of those situations could be the outside image website link in chat messages. We already know just the application utilizes recipient-side link previews, and also the demand to your outside resource is performed in recipient’s context. The authorization header is roofed into the GET demand into the image that is external. And so the bearer token gets leaked towards the outside domain. Whenever a harmful transmitter delivers a picture website website website link pointing to an attacker managed host, not just do they get recipient’s internet protocol address, nevertheless they additionally obtain victim’s session token. This is certainly a vulnerability that is critical it permits session hijacking.

Keep in mind that unlike phishing, this assault doesn’t need the target to go through the website website link. If the message containing the image website website website link is seen, the application immediately leaks the session token into the attacker.

It appears to be always a bug linked to the reuse of the okHttp client object that is global. It might be most readily useful if the designers make certain the software just attaches authorization bearer header in needs into the League API.


I didn’t find any vulnerabilities that are particularly interesting CMB, but that doesn’t suggest CMB is more protected compared to the League. (See Limitations and future research). Used to do locate a security that is few within the League, none of that have been specially tough to learn or exploit. I suppose it truly is the mistakes that are common make again and again. OWASP top ten anybody?

As customers we have to be careful with which companies we trust with your information.

Vendor’s reaction

I did so get a response that is prompt The League after delivering them a contact alerting them regarding the findings. The S3 bucket setup ended up being swiftly fixed. One other weaknesses had been patched or at the very least mitigated in just a couple of weeks.

I do believe startups could offer bug bounties certainly. It really is a gesture that is nice and much more significantly, platforms like HackerOne offer scientists an appropriate way to the disclosure of weaknesses. Unfortuitously neither of this two apps into the post has such system.

Restrictions and research that is future

This scientific studies are maybe perhaps not comprehensive, and really should never be regarded as a protection review. The majority of the tests in this article had been done regarding the community IO degree, and almost no on the customer it self. Particularly, we did not test for remote code execution or buffer overflow kind weaknesses. In the future research, we’re able to look more in to the protection associated with customer applications.

This may be completed with powerful analysis, making use of techniques such as for example: