You need to patch your Samba installation as soon as possible

The major Linux distributions rolled out security fixes for a use-after-free error, tracked as CVE-2017-14746, affecting all versions of SAMBA since 4.0.

The major Linux distributions (Red Hat, Ubuntu, Debian and others) rolled out security patches for a use-after-free error, tracked as CVE-2017-14746, affecting all versions of SAMBA since 4.0.

Administrations have to apply the fixes to their distributions, another possibility consists in turning off SAMBA 1, and operation that could hide some difficulties.

According to the project’s advisory, an attacker can use a malicious SMB1 request to control the contents of heap memory via a deallocated heap pointer.

“All versions of Samba from 4.0.0 onwards are vulnerable to a use after free vulnerability, where a malicious SMB1 request can be used to control the contents of heap memory via a deallocated heap pointer. It is possible this may be used to compromise the server.” reads the advisory.

The patch to fix the issue is available at the following URL:

http://www.samba.org/samba/security/

The versions 4.7.3, 4.6.11 and 4.5.15 have been issued to address the vulnerability.

The maintainers of the project have also issued patches for older versions at:

http://samba.org/samba/patches/.

The advisory includes also a workaround, it consists in preventing SMB1 access to the server by setting the parameter:

server min protocol = SMB2

to the [global] section of your smb.conf and restart smbd.

Unfortunately, the advisory warns of problems, older clients to be unable to connect to the server.

Administrators running vulnerable versions are advised to apply the patch as soon as possible.

There is also another flaw, tracked as CVE-2017-15275, that affects all the versions from 3.6.0 onwards that has been fixed by Samba.

According to the advisory, the server may return the contents of heap allocated memory to the client revealing “password hashes or other high-value data”.

“There is no known vulnerability associated with this error, but uncleared heap memory may contain previously used data that may help an attacker compromise the server via other methods. Uncleared heap memory may potentially contain password hashes or other high-value data.” reads the advisory.

Patched versions have been made available here.

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Pierluigi Paganini

(Security Affairs – networking, hacking)

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Pierluigi Paganini

Pierluigi Paganini is member of the ENISA (European Union Agency for Network and Information Security) Threat Landscape Stakeholder Group and Cyber G7 Group, he is also a Security Evangelist, Security Analyst and Freelance Writer. Editor-in-Chief at "Cyber Defense Magazine", Pierluigi is a cyber security expert with over 20 years experience in the field, he is Certified Ethical Hacker at EC Council in London. The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US. Pierluigi is a member of the "The Hacker News" team and he is a writer for some major publications in the field such as Cyber War Zone, ICTTF, Infosec Island, Infosec Institute, The Hacker News Magazine and for many other Security magazines. Author of the Books "The Deep Dark Web" and “Digital Virtual Currency and Bitcoin”.