apportproject apport CVE-2020-8833 in Apportproject and Canonical Products
Published on April 22, 2020

Apport race condition in crash report permissions

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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.

Vendor Advisory NVD

Vulnerability Analysis

CVE-2020-8833 can be exploited with local system access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity and availability.

Attack Vector:
LOCAL
Attack Complexity:
HIGH
Privileges Required:
LOW
User Interaction:
NONE
Scope:
CHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
NONE
Availability Impact:
NONE

Weakness Type

What is a TOCTTOU Vulnerability?

The software checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the software to perform invalid actions when the resource is in an unexpected state. This weakness can be security-relevant when an attacker can influence the state of the resource between check and use. This can happen with shared resources such as files, memory, or even variables in multithreaded programs.

CVE-2020-8833 has been classified to as a TOCTTOU vulnerability or weakness.


Products Associated with CVE-2020-8833

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2020-8833 are published in these products:

Apportproject Apport
 
Canonical Ubuntu Linux
 
Canonical Apport
 

Affected Versions

Canonical Apport:

Exploit Probability

EPSS
0.03%
Percentile
9.70%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.