ID CVE-2020-8833
Summary Time-of-check Time-of-use Race Condition vulnerability on crash report ownership change in Apport allows for a possible privilege escalation opportunity. If fs.protected_symlinks is disabled, this can be exploited between the os.open and os.chown calls when the Apport cron script clears out crash files of size 0. A symlink with the same name as the deleted file can then be created upon which chown will be called, changing the file owner to root. Fixed in versions 2.20.1-0ubuntu2.23, 2.20.9-0ubuntu7.14, 2.20.11-0ubuntu8.8 and 2.20.11-0ubuntu22.
References
Vulnerable Configurations
  • cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
    cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
  • cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:*
    cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:*
  • cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:*
    cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:*
  • cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
    cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
  • cpe:2.3:a:apport_project:apport:-:*:*:*:*:*:*:*
    cpe:2.3:a:apport_project:apport:-:*:*:*:*:*:*:*
CVSS
Base: 1.9 (as of 07-10-2022 - 15:14)
Impact:
Exploitability:
CWE CWE-367
CAPEC
  • Leveraging Race Conditions via Symbolic Links
    This attack leverages the use of symbolic links (Symlinks) in order to write to sensitive files. An attacker can create a Symlink link to a target file not otherwise accessible to her. When the privileged program tries to create a temporary file with the same name as the Symlink link, it will actually write to the target file pointed to by the attackers' Symlink link. If the attacker can insert malicious content in the temporary file she will be writing to the sensitive file by using the Symlink. The race occurs because the system checks if the temporary file exists, then creates the file. The attacker would typically create the Symlink during the interval between the check and the creation of the temporary file.
  • Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions
    This attack targets a race condition occurring between the time of check (state) for a resource and the time of use of a resource. A typical example is file access. The adversary can leverage a file access race condition by "running the race", meaning that they would modify the resource between the first time the target program accesses the file and the time the target program uses the file. During that period of time, the adversary could replace or modify the file, causing the application to behave unexpectedly.
Access
VectorComplexityAuthentication
LOCAL MEDIUM NONE
Impact
ConfidentialityIntegrityAvailability
PARTIAL NONE NONE
cvss-vector via4 AV:L/AC:M/Au:N/C:P/I:N/A:N
refmap via4
confirm
ubuntu USN-4315-2
Last major update 07-10-2022 - 15:14
Published 22-04-2020 - 22:15
Last modified 07-10-2022 - 15:14
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