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CVE-2022-28657

Apport fails to disable Python crash handler prior to chroot execution.

  • CVSS 7.8
  • CWE-400
  • Configuration Issues
  • Local

Apport does not disable python crash handler before entering chroot

CVE
CVE-2022-28657
CWE
CWE-400
CVSS base score
7.8
Published
2024-06-04
OWASP
A06 Security Misconfiguration
Orthogonal defect classification
Checking
Code defect classification
Missing Check
Category
Configuration Issues
Subcategory
Security Misconfigurations
Accessibility scope
Local
Impact
Privilege Escalation
Affected component
Apport

Solution

Upgrade to Apport version 2.20.1-0ubuntu2.3 or later, which disables the Python crash handler before entering chroot.

Vulnerable code sample

import os

def enter_chroot(new_root):
    os.chroot(new_root)
    os.chdir('/')

if __name__ == "__main__":
    new_root = "/path/to/new/root"
    enter_chroot(new_root)

Patched code sample

import os
import sys
import signal

def disable_crash_handler():
    signal.signal(signal.SIGSEGV, signal.SIG_DFL)

def enter_chroot(new_root):
    disable_crash_handler()
    
    os.chroot(new_root)
    os.chdir('/')

if __name__ == "__main__":
    new_root = "/path/to/new/root"
    enter_chroot(new_root)

Payload

import os
import ctypes

# Example payload to trigger a segmentation fault
def trigger_segmentation_fault():
    ctypes.string_at(0)  # Attempt to access an invalid memory address

# Enter chroot before triggering the fault
def enter_chroot(new_root):
    os.chroot(new_root)
    os.chdir('/')

# Example usage
if __name__ == "__main__":
    new_root = "/path/to/new/root"
    enter_chroot(new_root)
    trigger_segmentation_fault()

Cite this entry

@misc{vaitp:cve202228657,
  title        = {{Apport fails to disable Python crash handler prior to chroot execution.}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2024},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2022-28657},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2022-28657/}}
}
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