To give you the best possible experience, this site uses cookies. Review our Privacy Policy and Terms of Service to learn more. Ik snap het!
Artwork

Alex Murray Ubuntu Security Team Linux Tech Operating Systems Alex and Joe Security Software Development
Inhoud geleverd door Alex Murray and Ubuntu Security Team. Alle podcastinhoud, inclusief afleveringen, afbeeldingen en podcastbeschrijvingen, wordt rechtstreeks geüpload en geleverd door Alex Murray and Ubuntu Security Team of hun podcastplatformpartner. Als u denkt dat iemand uw auteursrechtelijk beschermde werk zonder uw toestemming gebruikt, kunt u het hier beschreven proces https://nl.player.fm/legal volgen.

Overeenkomstig met Ubuntu Security Podcast

Player FM - Podcast-app
Ga offline met de app Player FM !
Get it on App Store Get it on Google Play

Ubuntu Security Podcast « »
Episode 235

17:40
 
Spelen
Spelen
Delen
 

MP3•Thuis aflevering
Manage episode 435684709 series 2423058
Inhoud geleverd door Alex Murray and Ubuntu Security Team. Alle podcastinhoud, inclusief afleveringen, afbeeldingen en podcastbeschrijvingen, wordt rechtstreeks geüpload en geleverd door Alex Murray and Ubuntu Security Team of hun podcastplatformpartner. Als u denkt dat iemand uw auteursrechtelijk beschermde werk zonder uw toestemming gebruikt, kunt u het hier beschreven proces https://nl.player.fm/legal volgen.

Overview

A recent Microsoft Windows update breaks Linux dual-boot - or does it? This week we look into reports of the recent Windows patch-Tuesday update breaking dual-boot, including a deep-dive into the technical details of Secure Boot, SBAT, grub, shim and more, plus we look at a vulnerability in GNOME Shell and the handling of captive portals as well.

This week in Ubuntu Security Updates

135 unique CVEs addressed

[USN-6960-1] RMagick vulnerability

  • 1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS)

[USN-6951-2] Linux kernel (Azure) vulnerabilities

[USN-6961-1] BusyBox vulnerabilities

[USN-6962-1] LibreOffice vulnerability

  • 1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Noble (24.04 LTS)

[USN-6963-1] GNOME Shell vulnerability (01:03)

  • 1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Noble (24.04 LTS)
  • Captive portal detection would spawn an embedded webkit browser automatically to allow user to login etc
  • But the page the user gets directed to is controlled by the attacker and can contain arbitrary javascript etc
  • Upstream bug report claimed could then get a reverse shell etc - not clear this is the case since would still be constrained by the webkitgtk browser so would also need a sandbox escape etc.
  • This update then includes a change to both not automatically open the captive portal page (instead it will show a notification and the user needs to click that) BUT to also disable the use of the webkitgtk-based embedded browser and instead use the users regular browser

[USN-6909-3] Bind vulnerabilities

[USN-6964-1] ORC vulnerability

  • 1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Noble (24.04 LTS)

[USN-6837-2] Rack vulnerabilitie

[USN-6966-1] Firefox vulnerabilities

[USN-6966-2] Firefox regressions

[USN-6951-3] Linux kernel (Azure) vulnerabilities

[USN-6968-1] PostgreSQL vulnerability

  • 1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Noble (24.04 LTS)

[USN-6967-1] Intel Microcode vulnerabilities

[LSN-0106-1] Linux kernel vulnerability

[USN-6969-1] Cacti vulnerabilities

[USN-6970-1] exfatprogs vulnerability

[USN-6944-2] curl vulnerability

  • 1 CVEs addressed in Trusty ESM (14.04 ESM), Xenial ESM (16.04 ESM), Bionic ESM (18.04 ESM)

[USN-6965-1] Vim vulnerabilities

Goings on in Ubuntu Security Community

Reports of dual-boot Linux/Windows machines failing to boot (04:30)

  • https://arstechnica.com/security/2024/08/a-patch-microsoft-spent-2-years-preparing-is-making-a-mess-for-some-linux-users/
  • https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2022-2601
  • https://discourse.ubuntu.com/t/sbat-self-check-failed-mitigating-the-impact-of-shim-15-7-revocation-on-the-ubuntu-boot-process-for-devices-running-windows/47378
  • Microsoft released an update for Windows on 13th August 2024 - revoking old versions of grub that were susceptible to CVE-2022-2601
  • How do you revoke grub?
    • Secure Boot relies on each component in the boot chain verifying that the next component is signed with a valid signature before it is then loaded
      • UEFI BIOS validates shim
      • shim validates grub
      • grub validates kernel
      • kernel validates kernel modules etc
    • UEFI specification has effectively a CRL - list of hashes of binaries which shouldn’t be trusted
    • BUT there is only limited space in the UEFI storage - after the original BootHole vulnerabilities revoked a huge number of grub binaries from many different distros, some devices failed to boot as the NVRAM was too full
    • Microsoft and Red Hat and other maintainers of shim decided on a new scheme, called SBAT - Secure Boot Advanced Targeting
      • maintains a generation number for each component in the boot chain
      • when say shim or grub gets updated to fix a bunch more security vulnerabilities, upstream bumps the generation number
      • shim/grub then embeds the generation number within itself
      • Signed UEFI variable then lists which generation numbers are acceptable
    • shim checks the generation number of a binary (grub/fwupd etc) against this list and if it is too old refuses to load it
  • In Ubuntu this was patched back in Jan 2023 and was documented on the Ubuntu Discourse - in this case we updated shim to a newer version which itself revoked an older grub, grub,1
  • Now Microsoft’s update revokes grub,2, ie sets the minimum generation number for grub to 3
  • You can inspect the SBAT policy by either directly reading the associated EFI variable or using mokutil --list-sbat-revocations
cat /sys/firmware/efi/efivars/SbatLevelRT-605dab50-e046-4300-abb6-3dd810dd8b23 mokutil --list-sbat-revocations 
sbat,1,2023012900 shim,2 grub,3 grub.debian,4 
objdump -j .sbat -s /boot/efi/EFI/ubuntu/grubx64.efi | xxd -r 
sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md grub,4,Free Software Foundation,grub,2.12,https://www.gnu.org/software/grub/ grub.ubuntu,2,Ubuntu,grub2,2.12-5ubuntu4,https://www.ubuntu.com/ grub.peimage,2,Canonical,grub2,2.12-5ubuntu4,https://salsa.debian.org/grub-team/grub/-/blob/master/debian/patches/secure-boot/efi-use-peimage-shim.patch 
rm -rf grub2-signed mkdir grub2-signed pushd grub2-signed >/dev/null || exit for rel in focal jammy noble; do  mkdir $rel  pushd $rel >/dev/null || exit  pull-lp-debs grub2-signed $rel-security 1>/dev/null 2>/dev/null || pull-lp-debs grub2-signed $rel-release 1>/dev/null 2>/dev/null  dpkg-deb -x grub-efi-amd64-signed*.deb grub2-signed  echo $rel  echo -----  find . -name grubx64.efi.signed -exec objdump -j .sbat -s {} \; | tail -n +5 | xxd -r  popd >/dev/null || exit done popd >/dev/null 
focal ----- sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md grub,4,Free Software Foundation,grub,2.06,https://www.gnu.org/software/grub/ grub.ubuntu,1,Ubuntu,grub2,2.06-2ubuntu14.4,https://www.ubuntu.com/ jammy ----- sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md grub,4,Free Software Foundation,grub,2.06,https://www.gnu.org/software/grub/ grub.ubuntu,1,Ubuntu,grub2,2.06-2ubuntu14.4,https://www.ubuntu.com/ noble ----- sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md grub,4,Free Software Foundation,grub,2.12,https://www.gnu.org/software/grub/ grub.ubuntu,2,Ubuntu,grub2,2.12-1ubuntu7,https://www.ubuntu.com/ grub.peimage,2,Canonical,grub2,2.12-1ubuntu7,https://salsa.debian.org/grub-team/grub/-/blob/master/debian/patches/secure-boot/efi-use-peimage-shim.patch 
rm -rf shim-signed mkdir shim-signed pushd shim-signed >/dev/null || exit for rel in focal jammy noble; do  mkdir $rel  pushd $rel >/dev/null || exit  pull-lp-debs shim-signed $rel-security 1>/dev/null 2>/dev/null || pull-lp-debs shim-signed $rel-release 1>/dev/null 2>/dev/null  dpkg-deb -x shim-signed*.deb shim-signed  echo $rel  echo -----  find . -name shimx64.efi.signed.latest -exec objdump -j .sbat -s {} \; | tail -n +5 | xxd -r  popd >/dev/null || exit done popd >/dev/null 
focal ----- sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md shim,3,UEFI shim,shim,1,https://github.com/rhboot/shim shim.ubuntu,1,Ubuntu,shim,15.7-0ubuntu1,https://www.ubuntu.com/ jammy ----- sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md shim,3,UEFI shim,shim,1,https://github.com/rhboot/shim shim.ubuntu,1,Ubuntu,shim,15.7-0ubuntu1,https://www.ubuntu.com/ noble ----- sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md shim,4,UEFI shim,shim,1,https://github.com/rhboot/shim shim.ubuntu,1,Ubuntu,shim,15.8-0ubuntu1,https://www.ubuntu.com/

  • only noble has a new-enough shim in the security/release pocket - both focal and jammy have the older one - but the new 4th generation shim is currently undergoing testing in the -proposed pocket and will be released next week

  • until then, if affected, need to disable secure boot in BIOS then can either wait until the new shim is released OR just reboot twice in this mode and shim will automoatically reset the SBAT policy to the previous version, allowing the older shim to still be used

  • then can re-enable Secure Boot in BIOS

  • Once new shim is released it will reinstall the new SBAT policy to revoke its older version

  • One other thing, this also means the old ISOs won’t boot either

    • 24.04.1 will be released on 29th August
    • upcoming 22.04.5 release will also have this new shim too
    • no further ISO spins planned for 20.04 - so if you really want to install this release on new hardware, would need to disable secure boot first, do the install, then install updates to get the new shim, and re-enable secure boot

Get in contact

…   continue reading

244 afleveringen

#Alex Murray #Ubuntu Security Team #Linux #Tech #Operating Systems #Alex and Joe #Security #Software Development
Artwork

Episode 235

Ubuntu Security Podcast

147 subscribers

published

Spelen Spelen
iconDelen
 
MP3•Thuis aflevering
Manage episode 435684709 series 2423058
Inhoud geleverd door Alex Murray and Ubuntu Security Team. Alle podcastinhoud, inclusief afleveringen, afbeeldingen en podcastbeschrijvingen, wordt rechtstreeks geüpload en geleverd door Alex Murray and Ubuntu Security Team of hun podcastplatformpartner. Als u denkt dat iemand uw auteursrechtelijk beschermde werk zonder uw toestemming gebruikt, kunt u het hier beschreven proces https://nl.player.fm/legal volgen.

Overview

A recent Microsoft Windows update breaks Linux dual-boot - or does it? This week we look into reports of the recent Windows patch-Tuesday update breaking dual-boot, including a deep-dive into the technical details of Secure Boot, SBAT, grub, shim and more, plus we look at a vulnerability in GNOME Shell and the handling of captive portals as well.

This week in Ubuntu Security Updates

135 unique CVEs addressed

[USN-6960-1] RMagick vulnerability

  • 1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS)

[USN-6951-2] Linux kernel (Azure) vulnerabilities

[USN-6961-1] BusyBox vulnerabilities

[USN-6962-1] LibreOffice vulnerability

  • 1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Noble (24.04 LTS)

[USN-6963-1] GNOME Shell vulnerability (01:03)

  • 1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Noble (24.04 LTS)
  • Captive portal detection would spawn an embedded webkit browser automatically to allow user to login etc
  • But the page the user gets directed to is controlled by the attacker and can contain arbitrary javascript etc
  • Upstream bug report claimed could then get a reverse shell etc - not clear this is the case since would still be constrained by the webkitgtk browser so would also need a sandbox escape etc.
  • This update then includes a change to both not automatically open the captive portal page (instead it will show a notification and the user needs to click that) BUT to also disable the use of the webkitgtk-based embedded browser and instead use the users regular browser

[USN-6909-3] Bind vulnerabilities

[USN-6964-1] ORC vulnerability

  • 1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Noble (24.04 LTS)

[USN-6837-2] Rack vulnerabilitie

[USN-6966-1] Firefox vulnerabilities

[USN-6966-2] Firefox regressions

[USN-6951-3] Linux kernel (Azure) vulnerabilities

[USN-6968-1] PostgreSQL vulnerability

  • 1 CVEs addressed in Focal (20.04 LTS), Jammy (22.04 LTS), Noble (24.04 LTS)

[USN-6967-1] Intel Microcode vulnerabilities

[LSN-0106-1] Linux kernel vulnerability

[USN-6969-1] Cacti vulnerabilities

[USN-6970-1] exfatprogs vulnerability

[USN-6944-2] curl vulnerability

  • 1 CVEs addressed in Trusty ESM (14.04 ESM), Xenial ESM (16.04 ESM), Bionic ESM (18.04 ESM)

[USN-6965-1] Vim vulnerabilities

Goings on in Ubuntu Security Community

Reports of dual-boot Linux/Windows machines failing to boot (04:30)

  • https://arstechnica.com/security/2024/08/a-patch-microsoft-spent-2-years-preparing-is-making-a-mess-for-some-linux-users/
  • https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2022-2601
  • https://discourse.ubuntu.com/t/sbat-self-check-failed-mitigating-the-impact-of-shim-15-7-revocation-on-the-ubuntu-boot-process-for-devices-running-windows/47378
  • Microsoft released an update for Windows on 13th August 2024 - revoking old versions of grub that were susceptible to CVE-2022-2601
  • How do you revoke grub?
    • Secure Boot relies on each component in the boot chain verifying that the next component is signed with a valid signature before it is then loaded
      • UEFI BIOS validates shim
      • shim validates grub
      • grub validates kernel
      • kernel validates kernel modules etc
    • UEFI specification has effectively a CRL - list of hashes of binaries which shouldn’t be trusted
    • BUT there is only limited space in the UEFI storage - after the original BootHole vulnerabilities revoked a huge number of grub binaries from many different distros, some devices failed to boot as the NVRAM was too full
    • Microsoft and Red Hat and other maintainers of shim decided on a new scheme, called SBAT - Secure Boot Advanced Targeting
      • maintains a generation number for each component in the boot chain
      • when say shim or grub gets updated to fix a bunch more security vulnerabilities, upstream bumps the generation number
      • shim/grub then embeds the generation number within itself
      • Signed UEFI variable then lists which generation numbers are acceptable
    • shim checks the generation number of a binary (grub/fwupd etc) against this list and if it is too old refuses to load it
  • In Ubuntu this was patched back in Jan 2023 and was documented on the Ubuntu Discourse - in this case we updated shim to a newer version which itself revoked an older grub, grub,1
  • Now Microsoft’s update revokes grub,2, ie sets the minimum generation number for grub to 3
  • You can inspect the SBAT policy by either directly reading the associated EFI variable or using mokutil --list-sbat-revocations
cat /sys/firmware/efi/efivars/SbatLevelRT-605dab50-e046-4300-abb6-3dd810dd8b23 mokutil --list-sbat-revocations 
sbat,1,2023012900 shim,2 grub,3 grub.debian,4 
objdump -j .sbat -s /boot/efi/EFI/ubuntu/grubx64.efi | xxd -r 
sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md grub,4,Free Software Foundation,grub,2.12,https://www.gnu.org/software/grub/ grub.ubuntu,2,Ubuntu,grub2,2.12-5ubuntu4,https://www.ubuntu.com/ grub.peimage,2,Canonical,grub2,2.12-5ubuntu4,https://salsa.debian.org/grub-team/grub/-/blob/master/debian/patches/secure-boot/efi-use-peimage-shim.patch 
rm -rf grub2-signed mkdir grub2-signed pushd grub2-signed >/dev/null || exit for rel in focal jammy noble; do  mkdir $rel  pushd $rel >/dev/null || exit  pull-lp-debs grub2-signed $rel-security 1>/dev/null 2>/dev/null || pull-lp-debs grub2-signed $rel-release 1>/dev/null 2>/dev/null  dpkg-deb -x grub-efi-amd64-signed*.deb grub2-signed  echo $rel  echo -----  find . -name grubx64.efi.signed -exec objdump -j .sbat -s {} \; | tail -n +5 | xxd -r  popd >/dev/null || exit done popd >/dev/null 
focal ----- sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md grub,4,Free Software Foundation,grub,2.06,https://www.gnu.org/software/grub/ grub.ubuntu,1,Ubuntu,grub2,2.06-2ubuntu14.4,https://www.ubuntu.com/ jammy ----- sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md grub,4,Free Software Foundation,grub,2.06,https://www.gnu.org/software/grub/ grub.ubuntu,1,Ubuntu,grub2,2.06-2ubuntu14.4,https://www.ubuntu.com/ noble ----- sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md grub,4,Free Software Foundation,grub,2.12,https://www.gnu.org/software/grub/ grub.ubuntu,2,Ubuntu,grub2,2.12-1ubuntu7,https://www.ubuntu.com/ grub.peimage,2,Canonical,grub2,2.12-1ubuntu7,https://salsa.debian.org/grub-team/grub/-/blob/master/debian/patches/secure-boot/efi-use-peimage-shim.patch 
rm -rf shim-signed mkdir shim-signed pushd shim-signed >/dev/null || exit for rel in focal jammy noble; do  mkdir $rel  pushd $rel >/dev/null || exit  pull-lp-debs shim-signed $rel-security 1>/dev/null 2>/dev/null || pull-lp-debs shim-signed $rel-release 1>/dev/null 2>/dev/null  dpkg-deb -x shim-signed*.deb shim-signed  echo $rel  echo -----  find . -name shimx64.efi.signed.latest -exec objdump -j .sbat -s {} \; | tail -n +5 | xxd -r  popd >/dev/null || exit done popd >/dev/null 
focal ----- sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md shim,3,UEFI shim,shim,1,https://github.com/rhboot/shim shim.ubuntu,1,Ubuntu,shim,15.7-0ubuntu1,https://www.ubuntu.com/ jammy ----- sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md shim,3,UEFI shim,shim,1,https://github.com/rhboot/shim shim.ubuntu,1,Ubuntu,shim,15.7-0ubuntu1,https://www.ubuntu.com/ noble ----- sbat,1,SBAT Version,sbat,1,https://github.com/rhboot/shim/blob/main/SBAT.md shim,4,UEFI shim,shim,1,https://github.com/rhboot/shim shim.ubuntu,1,Ubuntu,shim,15.8-0ubuntu1,https://www.ubuntu.com/

  • only noble has a new-enough shim in the security/release pocket - both focal and jammy have the older one - but the new 4th generation shim is currently undergoing testing in the -proposed pocket and will be released next week

  • until then, if affected, need to disable secure boot in BIOS then can either wait until the new shim is released OR just reboot twice in this mode and shim will automoatically reset the SBAT policy to the previous version, allowing the older shim to still be used

  • then can re-enable Secure Boot in BIOS

  • Once new shim is released it will reinstall the new SBAT policy to revoke its older version

  • One other thing, this also means the old ISOs won’t boot either

    • 24.04.1 will be released on 29th August
    • upcoming 22.04.5 release will also have this new shim too
    • no further ISO spins planned for 20.04 - so if you really want to install this release on new hardware, would need to disable secure boot first, do the install, then install updates to get the new shim, and re-enable secure boot

Get in contact

…   continue reading

244 afleveringen

#Alex Murray #Ubuntu Security Team #Linux #Tech #Operating Systems #Alex and Joe #Security #Software Development

Alle afleveringen

×
 
Loading …

Welkom op Player FM!

Player FM scant het web op podcasts van hoge kwaliteit waarvan u nu kunt genieten. Het is de beste podcast-app en werkt op Android, iPhone en internet. Aanmelden om abonnementen op verschillende apparaten te synchroniseren.

 

Overeenkomstig met Ubuntu Security Podcast

Luister naar 500+ onderwerpen
Player FM - Podcast-app
Ga offline met de app Player FM !
Get it on App Store Get it on Google Play

Korte handleiding

Top-podcasts
Bureau Sport Podcast
De Koffiecorner
NOS Langs de Lijn Sportforum
Macro met Boot en Mujagić | BNR
FOKCAST
Somertijd Podcast
Schokkend Nieuws Podcast
Gremlins Strike Back
Digitaal | BNR
NOS Met het Oog op Morgen
Argos
Leven Zonder Stress
Wetenschap Vandaag | BNR
Radio Swammerdam
Echt Gebeurd
De Correspondent
De Nieuwe Willem
De moord op Patrick
De Blankenberge Tapes
Player FM logo
Hulp of Veelgestelde vragen | Verbeteren | Adverteren
Kunst|Zakelijk|Komedie|Economie|Entertainment|Nieuws|Politiek|Religie
Wetenschap|Voetbal|Sport|Verhaal vertellen|Technologie|Waargebeurde verhalen
Copyright 2024 | Sitemap | Privacybeleid | Servicevoorwaarden | | auteursrechten
Episode being played series thumbnail
icon icon
Snelheid
Serie instellingen
1x
1x
Volume
100%
icon
icon icon
/

Bekijk Player FM in ...
Player FM
Browser
Chrome
Safari
Firefox