Bug 1610640 (CVE-2018-10918)

Summary: CVE-2018-10918 samba: DsCrackNames on a user without an SPN can trigger NULL-pointer de-reference
Product: [Other] Security Response Reporter: Sam Fowler <sfowler>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: abhgupta, abokovoy, anoopcs, asn, bmcclain, dbaker, dblechte, dfediuck, eedri, gdeschner, jokerman, jrivera, jstephen, lmohanty, madam, mgoldboi, michal.skrivanek, rhs-smb, sankarshan, sbonazzo, sbose, security-response-team, sherold, sisharma, smohan, ssaha, ssorce, sthangav, trankin, vbellur
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard: impact=moderate,public=20180816,reported=20180801,source=upstream,cvss3=5.2/CVSS:3.0/AV:A/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H,cwe=CWE-476,fedora-all/samba=affected,rhel-5/samba=notaffected,rhel-5/samba3x=notaffected,rhel-6/samba=notaffected,rhel-6/samba4=notaffected,rhel-7/samba=notaffected,rhev-m-4/samba=notaffected,rhes-3/samba=notaffected,openshift-online-3/samba-common=notaffected,rhel-8/samba=notaffected
Fixed In Version: samba 4.7.9, samba 4.8.4 Doc Type: If docs needed, set a value
Doc Text:
A null pointer dereference flaw was found in the way samba checked database outputs from the LDB database layer. An authenticated attacker could use this flaw to crash a samba server in an Active Diretory Domain Controller configuration.
Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---
Bug Depends On: 1617913, 1612807, 1617910    
Bug Blocks: 1610646    

Description Sam Fowler 2018-08-01 05:29:33 UTC
As per upstream advisory:

All versions of Samba from 4.7.0 onwards are vulnerable to a denial of service attack which can crash the "samba" process when Samba is an Active Directory Domain Controller.

Missing database output checks on the returned directory attributes from the LDB database layer cause the DsCrackNames call in the DRSUAPI server to crash when following a NULL pointer.

This call is only available after authentication.

There is no further vulnerability associated with this error, merely a denial of service.

Comment 2 Sam Fowler 2018-08-16 03:39:27 UTC
External Reference:

https://www.samba.org/samba/security/CVE-2018-10918.html

Comment 3 Sam Fowler 2018-08-16 07:13:22 UTC
Created samba tracking bugs for this issue:

Affects: fedora-all [bug 1617910]

Comment 5 Huzaifa S. Sidhpurwala 2018-08-17 05:38:30 UTC
Acknowledgments:

Name: Volker Mauel (the Samba project)