Must have been a turnip truck https://twitter.com/KimZetter/status/1384936715769503745

That's a dig at the turnipesque savvy of Cellebrite, which royally stumbled into this.

cf. https://www.dwt.com/blogs/privacy--security-law-blog/2015/03... > FCC chair Wheeler said the FCC “didn’t just fall off the turnip truck.” Through CALEA, CPNI, and CSRIC, Wheeler said the agency has been working to protect consumer privacy.

https://www.phrases.org.uk/meanings/fell-off-the-back-of-a-t...

I think it originated with "RTFM" which was an old unix admin way of saying read the fucking manual (or man page).

Edit: looking up a bit more, it seems like this idiom is used to denote goods sold for cheap because they were stolen. Like "Bob is selling genuine iPhones very cheap, I fear they fell from the back of a truck".

Edit edit: I initially took it as "we won't tell how we got this", because I didn't know this idiom, but it seems several people agree with this interpretation. Not necessarily stolen, but obtained from an undisclosed source.

Perhaps even in a faraday cage..

One of the screenshots[0] shows the VMware Tools Service running, so yeah, looks like a virtualized guest.

[0]: https://signal.org/blog/images/cellebrite-dlls-loaded.png

lol

Fortunately, parallel construction means you never really have to throw out bad evidence as long as you can find some good evidence too!

It reminds me of the story of https://en.wikipedia.org/wiki/Annie_Dookhan

It's a method that crooked law enforcement uses to deceive courts. It's so common as to have its own name now.

If I search a phone with a tainted UFED and get a conversation between Bob (my subject) and Carl (his friend) about the drugs they're selling, that conversation either exists or doesn't exist. Now, let's assume that the court won't accept this evidence, based on a defense argument that it should be inadmissible after seeing the vulnerabilities of UFED, as detailed by Signal.

The next investigative step in to go interview and search Carl, since there is probable cause to believe that a conversation occurred about their drug dealing on his phone. Unless I a) know my UFED is vulnerable and b) have reason to believe the text conversation between Bob and Carl is fake, my warrant for Carl's phone is valid. Now, I search Carl's phone with the same UFED and find the exact same conversation.

At this point, it's still possible for the UFED to have made the conversation up on both sides and for both extractions, and this would probably make the resulting conversation (and potentially everything in the report) inadmissible, but any admissions from Bob or Carl, including based on questions asked about the conversation itself, would still be admissible. I could show the report to Bob and Carl as evidence against them and get a confession, which would be admissible. Additionally, if the court determines that the UFED report is inadmissible based on the potentially for it to be forensically unsound, I would still have the phones themselves. UFED (except in rare circumstances) requires the phone to be unlocked before it can make its extraction. As such, I could manually browse the phone to the conversation in question and take photos of the phone with the real conversations between Bob and Carl. I could also verify through an ISP/messenger app that evidence of those conversations occurred (for example, metadata demonstrating matching times and message sizes that align with the potentially-fabricated message).

The FOTPT defense only applies to illegally obtained evidence. Assuming you obtained a valid warrant or consent to conduct the search, there was nothing illegal about the UFED extraction that would make the FOTPT defense applicable.

~~~ The undated documents show that federal agents are trained to “recreate” the investigative trail to effectively cover up where the information originated, a practice that some experts say violates a defendant’s Constitutional right to a fair trial. If defendants don’t know how an investigation began, they cannot know to ask to review potential sources of exculpatory evidence - information that could reveal entrapment, mistakes or biased witnesses. ~~~

If you believe any of "fruit of the poisonous tree" stuff makes any difference, I've got a bridge to sell you. There is clear evidence that DEA agents are trained to create a "clean" story of evidence around the illicit information they get.

Black-bag the opposition politican, and then black-bag her phone.

The defense lawyers have to read it, and the people in law enforcement need to read the cases where judges throw out Cellebrite evidence based on that.

95% of all criminal cases in the US are Plead out largely because the defendant can not afford competent legal representation

This is why all kinds of questionable investigative tactics are still used even some that have clearly been ruled unconstitutional, they know most of the time it will not matter, they just need to get enough to make an arrest, the system will destroy the person anyway no conviction needed, and most likely the person will plead guilty even if innocent just to make the abuse stop

If evidence is obviously (or with high chance) disputable, then it puts pressure even in those cases where the attorney recommends the defendant to eventually plead.

Or maybe the attorneys available to those who can't afford are just crap in general?

In theory yes, but in most cases that will be a overworked lawyer that has 100's or 1000's of other active cases, and will not spend time other than negotiation the best deal.

Even if you happen to get a good public defender that has the ability to devote lots of time to your individual case, they would have no budget to hire an expert witness to present the vulnerabilities in the Cell-bright software to a jury

Your best bet would be if the ACLU or EFF took an interest in your case, but they take on very few cases relatively speaking and tend to focus on precedent setting cases, or cases that have high public interest (or can be made to have high public interest)

>Or maybe the attorneys available to those who can't afford are just crap in general?

In some cases they are incompetent, however in most cases they are just underfunded and massively over worked. In most jurisdictions the public defenders office is funded is 1/10 or less of what the prosecutors office is funded at.

Consider https://www.securityweek.com/forensics-tool-flaw-allows-hack.... Have any cases been thrown out? I don't think so.

No need to tell the court how you found out about the lawnmowing for the neighbour that was never reported to the IRS...

[0] https://www.law.cornell.edu/wex/fruit_of_the_poisonous_tree

I think the police have been using "parallel construction" to get around that for some time.

https://en.wikipedia.org/wiki/Parallel_construction

> Parallel construction is a law enforcement process of building a parallel, or separate, evidentiary basis for a criminal investigation in order to conceal how an investigation actually began.[1]

> In the US, a particular form is evidence laundering, where one police officer obtains evidence via means that are in violation of the Fourth Amendment's protection against unreasonable searches and seizures, and then passes it on to another officer, who builds on it and gets it accepted by the court under the good-faith exception as applied to the second officer.[2] This practice gained support after the Supreme Court's 2009 Herring v. United States decision.

Now, that's not to say that cops wouldn't do this in order to finally get a case around a particular subject who was able to sidestep previous investigations or something. I just doubt that it happens often enough to be worthwhile.

A report doesn't have to be generated by PA. A forensic examiner is free to use other methods to examine the binary. So long as the examiner can explain all the actions and any artifacts that would be left behind.

Plus, most law enforcement seizes the device and keeps it until after the trial. If there were valid arguments against the authenticity of data in the extraction report, it would be easy to verify that data's existence by checking the phone, re-extracting the data using a known-clean UFED, etc. This isn't the end of the world by any means for legal mobile device searches.

For the UFED Touch, for example, the device runs the extraction and saved the result to a flash drive or external drive. This is then reviewed with the UFED software on another machine (laptop, desktop, whatever). What you're describing would mean that the extraction takes place (one-way. The Touch requests an ABD or iTunes backup process, phone responds with the backup files). The the malicious file in the backup pops and executes a command that runs software on the phone, thus infecting the phone with false data to cover the tracks and make the data on the report match the device. This is unreasonably complex, and I doubt any judge would accept it as enough to consider the data inadmissible. Let alone the fact that the data likely exists elsewhere in a verifiable way (Facebook Messenger, WhatsApp, Google Drive, etc), which the initial extraction results should give probable cause to the cops to obtain.

In the Metzler kidnapping case the first confession was not admissible in court which had been obtained under threat of torture.

Not to mention regimes that don’t actually care about things like evidence being “legally admissible”.

CoreFoundation is open source: https://github.com/opensource-apple/CF

libdispatch is open source: https://apple.github.io/swift-corelibs-libdispatch/post/libd...

ASL is open source: https://opensource.apple.com/source/syslog/syslog-349.1.1/li...

The objective C runtime is open source: https://github.com/opensource-apple/objc4/blob/master/APPLE_...

icu, pthread, zlib, and libxml did not even originate at Apple.

Signed by Apple's key!

That does not make me feel good about Signal.

In contrast, it would strike me as strange if a Signal user switched to another messenger that allowed the data extraction because they were uncomfortable with Signal blocking it.

The insinuation that my device may be host to something potentially malicious is concerning. It gets a little worse that it can change, without notice. I'd tend to trust Signal and their security, but the potential for that mechanism to be hijacked is always present. They've certainly made it hard, though, and I think the folks at Signal are probably clever enough that my anemic observations don't tell the whole story.

Do you use an iPhone or a phone with Google Play Services on it?

Those both have the technical capability of receiving targeted updates.

For example, let's say they extract the Signal message data from your phone. You successfully convince everyone that this data might have been the result of some tampering. However, that doesn't prevent investigators from using that message history to find the other person, and get them to testify against you.

That’s not a guarantee, of course, and it could be possible for police to corroborate that you had contact with someone else in another way (through records from a wireless carrier or by doing shoe leather investigative work) and use try to get data on that person to get them to testify, but if their only link was through messages that had been deemed inadmissible, they can’t use that witness.

The more likely question in a scenario you describe would be if the compromised Signal data would be enough to raise questions about the validity of all the data on the device. I.e., if Signal is out, can they use information from WhatsApp or iMessage or whatever. Past case law would suggest that once compromised, all of the evidence from the device is compromised — but a judge might rule otherwise.

It would be cool if Signal or another app could use those exploits they’ve uncovered to inject randomized data into the data stores of other messaging applications too. You know. Just as an experiment.

In the example being discussed here, it's absolutely still fine for LE and there isn't a need to find a secondary source that side-steps the FOTPT argument. In fact, I could drag a subject into an interview, take his phone and present a warrant to search his phone.

If he refuses to unlock the phone, I can say "fine, we'll use our special software instead" and take it back to another room. After the interview, I give him back his phone and immediately bring in his co-conspirator. If I show the conspirator fake messages between him and my first subject and get him to testify against my subject, that's still admissible. If this is the case, why would using potentially-false/unverifiable Cellebrite data be inadmissible?

Cellebrite has never claimed any particular exploits in Signal. Signal is exploitable in this particular way for entirely obvious and common reasons.

In computer forensics it's ALL about being able to verify, without a shadow of doubt that something is what they say it is. Chain of custody rules everything. This blasts a huge gaping hole in all that. He's proven that chain of custody can be tampered with and undetected. Files can be planted, altered or erased. Reports can altered. Timestamps can be changed. The host OS can be exploited. It calls all past and future cellbrite reports into question. Cellbrite can no longer guaranty their software acts in a consistent reliable verifiable way. It leaves doubt.

Mostly. The other side gets all the evidence that the opposing side sees. They both get a chance to review it.

> Chain of custody rules everything.

Agree.

> This blasts a huge gaping hole in all that.

Not really. The analysis goes in two steps. One is to pull all the data from the phone, in a chain-of-custody manner. In an adversarial case, both sides can do this.

The collection and analysis go into two steps. First is moving the data to windows box. Next is the analysis. As I understand it, the analysis portion is where things can explode. Then, if in the hands of someone skilled in forensics, the extracted data would be saved in some other device, possibly to be shared with the other side. Then the risky, potentially explosive analysis would be done. It is very unlikely that all previous cases exist on that device and nowhere else.

Therefore,

> It calls all past and future cellbrite reports into question.

is not true, as the extracted files are likely not on the collecting windows device.

In any case, it is not clear how many uses of this device are in actual legal environments.

This very blog post says they have found similar vulnerabilities in both steps.

Exploits may fuck up phone, backup and even cellebrite host os.

As such, phone, backed up data and reports are useless going forward.