Say what? Another reCaptcha attack, now against audio challenges

unCaptcha is the sound of security crumbling


Whatever Google has in mind to replace its reCaptcha had better be ready soon: another research group has found a way to defeat it.

Late last week, researchers from startup Vicarious demonstrated their attack against reCaptcha's image-based “I'm not a robot” proof. Now University of Maryland boffins have busted Google's audio accessibility feature.

The University's Kevin Bock, Daven Patel, George Hughey and Dave Levin call unCaptcha a low-resource defeat of the audio challenge that usually beats reCaptcha “less time than it takes to even play the audio challenge!”

By the numbers, they claim 85.15 per cent accuracy in 5.42 seconds over 450 reCaptcha challenges from live Websites.

The secret to getting cracking reCaptcha's audio so quickly? The cloud, of course: rather than running their own audio analysis, the researchers used multiple online speech-to-text services, as described in full in this paper [PDF]:

  • Download the audio captcha;
  • Segment the audio into individual digit audio clips;
  • Upload each segment to multiple online speech-to-text services;
  • Convert these services' responses to digits including:
    • Exact homophones: If it is "one" "two", etc., then guess that number
    • Near homophones: If it sounds like a digit, like "true" sounds like "two", then guess what it sounds like
    • Ensemble the multiple services together by taking a weighted vote based on confidence;
  • And finally upload the answer.

Some of this had already been demonstrated, the researchers explain, in a project called ReBreakCaptcha posted at GitHub in February.

The University of Maryland researchers say their main contribution is in improving audio pre-processing, so the online speech-to-text converters work more accurately.

Segmenting the audio, the paper explains, is easy: with no background noise added to reCaptcha, the pre-processing need only identify silence. With the segments identified, unCaptcha then adds two steps not attempted in ReBreakCaptcha: phonetic mapping, and ensembling.

The phonetic mapping stage handles things like homophones (too/two/to/2) and near-homophones (free/3, sex/6 – the latter, of course, a true homophone in New Zealand) so that what's passed to the speech-to-text engine gets a more accurate result.

“Ensembling” helps sort out which speech-to-text engines are most accurate by weighting results: “In essence, each candidate answer gets a weighted vote; the answer with the highest weight wins”, the paper says.

Possible countermeasures the paper suggests include giving reCaptcha a bigger vocabulary for its audio challenges, adding background noise to make it harder to segment the challenge into individual words, or making the challenge a set of instructions like “move your mouse upwards” or “type this word”. ®


Intel CPU interconnects can be exploited by malware to leak encryption keys and other info, academic study finds

Side-channel ring race 'hard to mitigate with existing defenses'

Chip-busting boffins in America have devised yet another way to filch sensitive data by exploiting Intel's processor design choices.

Doctoral student Riccardo Paccagnella, master's student Licheng Luo, and assistant professor Christopher Fletcher, all from the University of Illinois at Urbana-Champaign, delved into the way CPU ring interconnects work, and found they can be abused for side-channel attacks. The upshot is that one application can infer another application's private memory and snoop on the user's key presses.

"It is the first attack to exploit contention on the cross-core interconnect of Intel CPUs," Paccagnella told The Register. "The attack does not rely on sharing memory, cache sets, core-private resources or any specific uncore structures. As a consequence, it is hard to mitigate with existing side channel defenses."

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SolarWinds just keeps getting worse: New strain of backdoor malware found in probe

Plus: McAfee's in serious trouble over claimed cryptocurrency scam

In brief Another form of malware has been spotted on servers backdoored in the SolarWinds' Orion fiasco.

The strain, identified as SUNSHUTTLE by FireEye, is a second-stage backdoor written in Go which uses HTTPS to communicate with a command-and-control server for data exfiltration, adding new code as needed. Someone based in the US, perhaps at an infected organization, uploaded the malware to a public malware repository in August last year for analysis, well before the cyber-spying campaign became public.

Brandon Wales, acting director of the US Cybersecurity and Infrastructure Agency, warned it could take 18 months to clean up this mess, and that's looking increasingly likely.

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Linus Torvalds issues early Linux Kernel update to fix swapfile SNAFU

‘Subtle and very nasty bug’ meant 5.12 rc1 could trash entire filesystems

Linux overlord Linus Torvalds has rushed out a new release candidate of Linux 5.12 after the first in the new series was found to include a ‘subtle and very nasty bug’ that was so serious he marked rc1 as unsuitable for use.

“We had a very innocuous code cleanup and simplification that raised no red flags at all, but had a subtle and very nasty bug in it: swap files stopped working right. And they stopped working in a particularly bad way: the offset of the start of the swap file was lost,” Torvalds wrote in a March 3rd post to the Linux Kernel Mailing List.

“Swapping still happened, but it happened to the wrong part of the filesystem, with the obvious catastrophic end results.”

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Remember that day in March 2020 when you were asked to get the business working from home – tomorrow, if possible? Here's how that worked out

IT pros from orgs large and small tell The Reg the tech delivered, mostly, but couriers and home Wi-Fi suddenly became your problem

Covid Logfile Brianna Haley was given one day to be ready to roll out Zoom for 13,000 users at over 1,000 sites.

Haley* is a project analyst for a large healthcare provider that, as COVID-19 marched across the world in March 2020, realised imminent lockdowns meant it would soon be unable to consult with patients.

And no consultations meant no revenue.

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The torture garden of Microsoft Exchange: Grant us the serenity to accept what they cannot EOL

Time to fix those legacy evils, though.... right?

Column It is the monster which corrupts all it touches. It is an energy-sucking vampire that thrives on the pain it promotes. It cannot be killed, but grows afresh as each manifestation outdoes the last in awfulness and horror. It is Microsoft Exchange and its drooling minion, Outlook.

Let us start with the most numerous of its victims, the end users. Chances are, you are one. You may be numbed by lifelong exposure, your pain receptors and critical faculties burned out though years of corrosion. You might be like me, an habitual avoider whose work requirements periodically force its tentacles back in through the orifices.

I have recently started to use it through its web interface, where it doesn’t update the unread flags, hides attachments, multiplies browser instances, leaves temp files all over my download directory, tangles threads, botches searchers and so on.

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Just when you thought it was safe to enjoy a beer: Beware the downloaded patch applied in haste

Let us tell you a tale of the Mailman's Apprentice

Who, Me? The weekend is over and Monday is here. Celebrate your IT prowess with another there-but-for-the-grace confession from the Who, Me? archives.

Our tale, from a reader the Regomiser has elected to dub "Simon", takes us back to the early part of this century and to an anonymous antipodean institution of learning.

Simon was working at the local Student Union (or "guild" as the locals called it), which was having problems with uppity education staff censoring the emissions of students. Simon was therefore commissioned to set up a fully independent newsletter.

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US National Security Council urges review of Exchange Servers in wake of Hafnium attack

Don't just patch, check for p0wnage, says top natsec team

The Biden administration has urged users of Microsoft's Exchange mail and messaging server to ensure they have not fallen victim to the recently-detected "Hafnium" attack on Exchange Server that Microsoft says originated in China.

Microsoft revealed the attack last week and released Exchange security updates.

The Biden administration’s Cybersecurity and Infrastructure Security Agency (CISA) followed up with a March 5 general advisory encouraging upgrades to on-premises Exchange environments. Another advisory on 6 March upped the ante as follows:

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Delayed, overbudget and broken. Of course Microsoft's finest would be found in NASA's Orion

In Space No One Can Hear You Scream (as Windows crashes again)

BORK!BORK!BORK! Getting astronauts to the Moon or Mars is the least of NASA's problems. Persuading Microsoft Windows not to fall over along the way is apparently a far greater challenge.

Spotted by Register reader Scott during a visit to the otherwise excellent Space Center Houston, there is something all too real lurking within the mock-up of the Orion capsule in which NASA hopes to send its astronauts for jaunts beyond low Earth orbit.

Clutched in the hand of a mannequin posed in the capsule's hatch is a reminder of both how old space tech tends to be and a warning for space-farers intending to take Microsoft's finest out for a spin.

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NASA shows Mars that humans can drive a remote control space tank at .01 km/h

Perseverance takes first drive around landing spot named in honor of seminal sci-fi author Octavia E. Butler

NASA’s Perseverance rover trekked across Mars for the first time last Thursday, March 4, 2021.

The vehicle went four whole meters forward, turned 150 degrees to the left, then moved another two-and-a-half meters. The entire drive covered a whopping 6.5 m (21.3 feet) across Martian terrain. The journey took about 33 minutes.

The Register ran that through a calculator and deduces the nuclear powered laser-equipped space tank, aka Perseverance, sped along at the astounding velocity of .01km/h, quite a comedown from the 19,310 km/h at which it entered the red planet’s atmosphere.

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University of the Highlands and Islands shuts down campuses as it deals with 'ongoing cyber incident'

Ten letters, starts with R, ends with E, three syllables

The University of the Highlands and Islands (UHI) in Scotland is fending off "an ongoing cyber incident" that has shut down its campuses.

In a message to students and staff yesterday afternoon, the institution, which spans 13 locations across the northernmost part of the UK, warned that "most services" – including its Brightspace virtual learning environment – were affected.

"We are currently working to isolate and minimise impact from this incident with assistance from external partners. We do not believe personal data has been affected," said the university, adding: "The source of the incident is not yet known."

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