Vulnerabilities > CVE-2019-7307 - Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in Apport Project Apport
Attack vector
LOCAL Attack complexity
HIGH Privileges required
LOW Confidentiality impact
HIGH Integrity impact
HIGH Availability impact
HIGH Summary
Apport before versions 2.14.1-0ubuntu3.29+esm1, 2.20.1-0ubuntu2.19, 2.20.9-0ubuntu7.7, 2.20.10-0ubuntu27.1, 2.20.11-0ubuntu5 contained a TOCTTOU vulnerability when reading the users ~/.apport-ignore.xml file, which allows a local attacker to replace this file with a symlink to any other file on the system and so cause Apport to include the contents of this other file in the resulting crash report. The crash report could then be read by that user either by causing it to be uploaded and reported to Launchpad, or by leveraging some other vulnerability to read the resulting crash report, and so allow the user to read arbitrary files on the system.
Vulnerable Configurations
| Part | Description | Count |
|---|---|---|
| Application | 4 | |
| OS | 5 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (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. The typical example is the file access. The attacker can leverage a file access race condition by "running the race", meaning that he 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 attacker could do something such as replace the file and cause an escalation of privilege.
Nessus
| NASL family | Ubuntu Local Security Checks |
| NASL id | UBUNTU_USN-4051-1.NASL |
| description | Kevin Backhouse discovered a race-condition when reading the user |
| last seen | 2020-06-01 |
| modified | 2020-06-02 |
| plugin id | 126567 |
| published | 2019-07-09 |
| reporter | Ubuntu Security Notice (C) 2019-2020 Canonical, Inc. / NASL script (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof. |
| source | https://www.tenable.com/plugins/nessus/126567 |
| title | Ubuntu 16.04 LTS / 18.04 LTS / 18.10 / 19.04 : apport vulnerability (USN-4051-1) |
| code | |