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Android Security Auditing: Investigating Unauthorized Screenshots
- ggm 8y agoI did tell 1password I could see 'en clair' state in the recent apps view some number of versions ago. They said there wasn't much they could do about it.
- daveFNbuck 8y agoMaybe follow up and tell them to set FLAG_SECURE. It may help to mention that LastPass already does this.
- jarfil 8y agoI'm not a fan of 1password, but their Android app does block screenshots.
- procinct 8y agoWhy are you not a fan of 1Password?
- solarkraft 8y agoI can tell you why I'm not. Their software is not open source. Plus an open source competitor with good UX (and sync), Bitwarden, exists.
- deleted 8y ago[deleted]
- izacus 8y ago1Passwords Android app quality is pretty lacking in comparison to any other competitor, so it's not wierd that they didn't even enable the secure flag.
- brodyprice 8y agoThe screenshots were for "recent apps" navigation, they weren't being uploaded anywhere, apps can set "FLAG_SECURE" to prevent it, the device was rooted, and the files were "...inaccessible to most apps, except those to which I grant root access." ? Can someone explain to me what the problem is? Why are the screenshots considered unauthorized?
- RafiqM 8y agoThe conclusion is there's no problem, that it wasn't the nefarious activity that he originally thought it was. The additional point he's trying to make is that app developers should use FLAG_SECURE if its confidential data - messaging probably should be, and his bitcoin app should almost certainly be.
- brodyprice 8y agoAh, that makes sense, thank you. I think I was thrown off by the link's title, "Unauthorized Screenshots in Android Phones" - I read it as a security issue
- jarfil 8y agoKeepass2Android and Signal have it as an option, Orfox just enables it on webpages but disables it on the settings screen, Netflix enables it on video playback. My banking app doesn't have the option at all, yay banking!
- cpv 8y agoFirefox Focus has this enabled, and some banking/payment apps (the developers knew about the flag).
- izacus 8y agoHow is messaging confidental data? Remember, FLAG_SECURE prevents users from taking screenshots themselves as well and prevents display of content in several other cases (e.g. screen mirroring). Your conversations aren't nearly as sensitive to require such a large breach of usability.
- mr-ron 8y agoDisclaimer: This is not me, but someone I met through The Recurse Center ( https://www.recurse.com/ https://www.recurse.com/ ), and was enthralled by this story.
- deleted 8y ago[deleted]
- jancsika 8y agoFLAG_SECURE: * overworked, out-of-coffee developer of "secure" messaging app forgets to set FLAG_SECURE. Oops. vs. FLAG_CACHE_ARBITRARY_IMAGE_OF_MY_INTERFACE_TO_HELP_ANDROID_APPEAR_MORE_RESPONSIVE: * overworked developer of "secure" messaging app who is out of coffee forgets to set this flag. App doesn't appear more responsive but also doesn't cache an image of the interface. Yay security! * But... app devs default to not caching images of interfaces, thus Android appears less responsive overall to the user. FLAG_SECURE exists. Therefore Android's appearance of responsiveness trumps secure defaults in this case. Boo.
- Buge 8y agoBut will anyone be harmed by these screenshots? They're encrypted.
- clort 8y agoHow are they encrypted, if a disk scraper can find them and display the contents?
- dmitrygr 8y agoall user files are encrypted. no user password -> your disc scraper is useless.
- epse 8y agoThey are encrypted on disk, but like an encrypted hard drive, decrypted when the user logs in. I'm unsure if they are accessible when the phone is locked, I don't think so. And apps can't access it. The drive scanner found them because they were in unallocated space.
- Rjevski 8y agoThey are definitely accessible by root even if the phone is locked. Unmounting & mounting the partition every time you lock/unlock is impossible as presumably some system services will still have open file handles there (for legitimate reasons), not to mention the performance impact. The issue is that the OS now provides a convenient “backdoor” for root-privileged malware to capture sensitive data from any app effortlessly; it just needs to subscribe to file system events (using inotify) to grab the files as soon as they’re written. Without it, the malware developer would have to write hooks for each app they wanted to eavesdrop on individually, which raises the bar at least a little bit.
- esotericn 8y agoWhy can manual screenshots be prevented by applications? Automated screenshots - makes sense. But manual? I've lost count of the number of times I've had to resort to stupid nonsense like taking a photo of my phone with another phone. It provides zero security benefit whilst making the end user's life harder.
- FactolSarin 8y agoHow can the API ever be 100% sure it's a user-initiated screenshot?
- esotericn 8y agoIt's a physical button press.
- burner222 8y agocan someone tell me why these cached interfaces are even leaving memory/RAM