New Xen bug uses security feature to destroy security

Dis-ARM-ing flaw can cook your console


Xen has revealed details of bug CVE-2015-6654, which it warned about a couple of weeks back.

The good news is that this one is rather less nasty than the string of guest/host escapes it's reported lately thanks largely to leaks in QEMU. Another nice piece of news is that this time around the problem's also only on ARM-compatible silicon, so even fewer folk will need to reach for their patch-o-matics.

The bad news is that it's still a flaw and one that can create a denial of service attack on a Xen system.

“A malicious infrastructure domain, which is allowed to map memory of a foreign guest, would be able to flood the Xen console,” says the advice from the Xen Project about the bug.

“As a result, in a system designed to enhance security by radically disaggregating the management, the security may be reduced. But, the security will be no worse than a non-disaggregated design.”

Another little ray of sunshine comes from the fact that one mitigation is simply to reduce the hypervisor log level so that it sends fewer messages. With less logging, the chances of a DoS fall.

Here comes a little grey cloud: “Switching from disaggregated to a non-disaggregated operation does NOT mitigate these vulnerabilities. Rather, it simply recategorises the vulnerability to hostile management code, regarding it 'as designed'; thus it merely reclassifies these issues as 'not a bug'.”

“Users and vendors of disaggregated systems should not change their configuration.”

Patching is therefore recommended. Go look for xsa141.patch. And enjoy your upgrade. ®


Other stories you might like

  • Deepfake attacks can easily trick live facial recognition systems online
    Plus: Next PyTorch release will support Apple GPUs so devs can train neural networks on their own laptops

    In brief Miscreants can easily steal someone else's identity by tricking live facial recognition software using deepfakes, according to a new report.

    Sensity AI, a startup focused on tackling identity fraud, carried out a series of pretend attacks. Engineers scanned the image of someone from an ID card, and mapped their likeness onto another person's face. Sensity then tested whether they could breach live facial recognition systems by tricking them into believing the pretend attacker is a real user.

    So-called "liveness tests" try to authenticate identities in real-time, relying on images or video streams from cameras like face recognition used to unlock mobile phones, for example. Nine out of ten vendors failed Sensity's live deepfake attacks.

    Continue reading
  • Lonestar plans to put datacenters in the Moon's lava tubes
    How? Founder tells The Register 'Robots… lots of robots'

    Imagine a future where racks of computer servers hum quietly in darkness below the surface of the Moon.

    Here is where some of the most important data is stored, to be left untouched for as long as can be. The idea sounds like something from science-fiction, but one startup that recently emerged from stealth is trying to turn it into a reality. Lonestar Data Holdings has a unique mission unlike any other cloud provider: to build datacenters on the Moon backing up the world's data.

    "It's inconceivable to me that we are keeping our most precious assets, our knowledge and our data, on Earth, where we're setting off bombs and burning things," Christopher Stott, founder and CEO of Lonestar, told The Register. "We need to put our assets in place off our planet, where we can keep it safe."

    Continue reading
  • Conti: Russian-backed rulers of Costa Rican hacktocracy?
    Also, Chinese IT admin jailed for deleting database, and the NSA promises no more backdoors

    In brief The notorious Russian-aligned Conti ransomware gang has upped the ante in its attack against Costa Rica, threatening to overthrow the government if it doesn't pay a $20 million ransom. 

    Costa Rican president Rodrigo Chaves said that the country is effectively at war with the gang, who in April infiltrated the government's computer systems, gaining a foothold in 27 agencies at various government levels. The US State Department has offered a $15 million reward leading to the capture of Conti's leaders, who it said have made more than $150 million from 1,000+ victims.

    Conti claimed this week that it has insiders in the Costa Rican government, the AP reported, warning that "We are determined to overthrow the government by means of a cyber attack, we have already shown you all the strength and power, you have introduced an emergency." 

    Continue reading

Biting the hand that feeds IT © 1998–2022