CVE-2019-3880
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Description
A flaw was found in the way samba implemented an RPC endpoint emulating the Windows registry service API. An unprivileged attacker could use this flaw to create a new registry hive file anywhere they have unix permissions which could lead to creation of a new file in the Samba share.
Statement
This issue affects the version of samba shipped with Red Hat Gluster Storage 3, as it contains the vulnerable functionality.
Mitigation
Either turn off SMB1 by setting the global parameter:
'min protocol = SMB2'
or if SMB1 is required turn off unix extensions by setting the global parameter:
'unix extensions = no'
in the smb.conf file.
Additional information
- Bugzilla 1691518: samba: save registry file outside share as unprivileged user
- CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
- FAQ: Frequently asked questions about CVE-2019-3880
Common Vulnerability Scoring System (CVSS) Score Details
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).
| Red Hat | NVD | |
|---|---|---|
CVSS v3 Base Score | 4.2 | 5.4 |
Attack Vector | Network | Network |
Attack Complexity | High | Low |
Privileges Required | Low | Low |
User Interaction | None | None |
Scope | Unchanged | Unchanged |
Confidentiality Impact | None | None |
Integrity Impact | Low | Low |
Availability Impact | Low | Low |
CVSS v3 Vector
Red Hat: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L
NVD: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
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 Michael Hanselmann for reporting this issue.
Frequently Asked Questions
Why is Red Hat's CVSS v3 score or Impact different from other vendors?
My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?
What can I do if my product is listed as "Will not fix"?
What can I do if my product is listed as "Fix deferred"?
What is a mitigation?
I have a Red Hat product but it is not in the above list, is it affected?
Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?
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