Ubuntu

A significant vulnerability in Ubuntu 25.04 allows attackers with physical access to bypass Secure Boot protections by exploiting debug shells in the initramfs during boot failures. This enables persistent malware injection that survives reboots and maintains access even after correct password entry for encrypted partitions. The attack involves injecting malicious hooks into the initramfs, circumventing traditional security measures. Mitigations include modifying kernel parameters to disable debug shells and implementing advanced encryption methods.

Source: https://cybersecuritynews.com/linux-boot-vulnerability-allows-bypass-of-secure-boot-protections/

TPRM report: https://www.rankiteo.com/company/ubuntu-research-inc

"id": "ubu948080725",
"linkid": "ubuntu-research-inc",
"type": "Vulnerability",
"date": "7/2025",
"severity": "50",
"impact": "2",
"explanation": "Attack limited on finance or reputation"

{'affected_entities': [{'industry': 'Technology',
                        'name': 'Ubuntu',
                        'type': 'Operating System'},
                       {'industry': 'Technology',
                        'name': 'Debian',
                        'type': 'Operating System'},
                       {'industry': 'Technology',
                        'name': 'Fedora',
                        'type': 'Operating System'},
                       {'industry': 'Technology',
                        'name': 'AlmaLinux',
                        'type': 'Operating System'}],
 'attack_vector': 'Physical Access',
 'description': 'A significant vulnerability affecting modern Linux '
                'distributions that allows attackers with brief physical '
                'access to bypass Secure Boot protections through initramfs '
                'manipulation. The attack exploits debug shells accessible '
                'during boot failures, enabling persistent malware injection '
                'that survives system reboots and maintains access even after '
                'users enter correct passwords for encrypted partitions.',
 'impact': {'systems_affected': ['Ubuntu 25.04',
                                 'Debian 12',
                                 'Fedora 42',
                                 'AlmaLinux 10']},
 'initial_access_broker': {'backdoors_established': 'Malicious hooks in '
                                                    'scripts/local-bottom/',
                           'entry_point': 'Debug shells during boot failures'},
 'lessons_learned': 'The vulnerability highlights the importance of securing '
                    'the initramfs component and the risks associated with '
                    'physical access to systems.',
 'post_incident_analysis': {'corrective_actions': ['Modify kernel parameters',
                                                   'Implement UKIs and TPMs'],
                            'root_causes': 'Unsigned initramfs components and '
                                           'debug shell access during boot '
                                           'failures'},
 'recommendations': ['Modify kernel command-line parameters to disable debug '
                     'shells',
                     'Use Unified Kernel Images (UKIs)',
                     'Implement Trusted Platform Modules (TPMs)'],
 'references': [{'source': "Alexander Moch's research"}],
 'response': {'containment_measures': ['Modifying kernel command-line '
                                       'parameters',
                                       'Configuring bootloader password '
                                       'requirements',
                                       'Enabling SSD native encryption',
                                       'Implementing LUKS encryption for boot '
                                       'partitions'],
              'remediation_measures': ['Unified Kernel Images (UKIs)',
                                       'Trusted Platform Modules (TPMs)']},
 'title': 'Linux initramfs Vulnerability Bypassing Secure Boot',
 'type': 'Vulnerability Exploitation',
 'vulnerability_exploited': 'initramfs debug shell access during boot failures'}