CVE-2020-14352
Description
A flaw was found in librepo. A directory traversal vulnerability was found where it failed to sanitize paths in remote repository metadata. An attacker controlling a remote repository may be able to copy files outside of the destination directory on the targeted system via path traversal. This flaw could potentially result in system compromise via the overwriting of critical system files. The highest threat from this flaw is to users that make use of untrusted third-party repositories.
Statement
This issue is rated as having Moderate impact on Red Hat Enterprise Linux 7 because DNF is not installed by default. The DNF package is available through the Extras channel as an enhancement to YUM 3. Both Fedora and Red Hat Enterprise Linux leverage transport security and package signatures to ship software to their users in a safe way.
Fedora provides a centralized, non-mirrored Fedora-run metalink service which provides a list if active mirrors and the expected cryptographic digest of the repomd.xml files. yum uses this information to select a mirror and verify that it serves the up-to-date, untampered repomd.xml. The chain of cryptographic digests is verified from there, eventually leading to verification of the .rpm file contents.
Red Hat uses a different option to distribute Red Hat Enterprise Linux and its RPM-based products: a content-distribution network, managed by a trusted third party. Furthermore, the repositories provided by Red Hat use a separate public key infrastructure which is managed by Red Hat. For further information, refer to the following articles.
Mitigation
Avoid downloading software from untrusted third-party mirrors. Note that under normal circumstances, this flaw does not pose any threat to Red Hat users, as repositories are fully trusted and controlled by Red Hat.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8 | 8 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | Required | Required | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
The attacker may be able to create or overwrite critical files that are used to execute code, such as programs or libraries.
Integrity
Technical Impact: Modify Files or Directories
The attacker may be able to overwrite or create critical files, such as programs, libraries, or important data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, appending a new account at the end of a password file may allow an attacker to bypass authentication.
Confidentiality
Technical Impact: Read Files or Directories
The attacker may be able read the contents of unexpected files and expose sensitive data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, by reading a password file, the attacker could conduct brute force password guessing attacks in order to break into an account on the system.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
The attacker may be able to overwrite, delete, or corrupt unexpected critical files such as programs, libraries, or important data. This may prevent the product from working at all and in the case of protection mechanisms such as authentication, it has the potential to lock out product users.
Acknowledgements
Red Hat would like to thank Sergei Iudin <siudin@fb.com> for reporting this issue.
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