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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.1852 samba security update 31 May 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: samba Publisher: Debian Operating System: Debian GNU/Linux Impact/Access: Increased Privileges -- Existing Account Create Arbitrary Files -- Remote with User Interaction Denial of Service -- Remote with User Interaction Provide Misleading Information -- Existing Account Reduced Security -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2021-20254 CVE-2019-14907 CVE-2019-14902 CVE-2019-14870 CVE-2019-14861 CVE-2019-14847 CVE-2019-14833 CVE-2019-10218 Reference: ESB-2021.1557 ESB-2021.1497 ESB-2021.1478 Original Bulletin: https://lists.debian.org/debian-lts-announce/2021/05/msg00023.html - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 - - ------------------------------------------------------------------------- Debian LTS Advisory DLA-2668-1 debian-lts@lists.debian.org https://www.debian.org/lts/security/ Abhijith PA May 29, 2021 https://wiki.debian.org/LTS - - ------------------------------------------------------------------------- Package : samba Version : 2:4.5.16+dfsg-1+deb9u4 CVE ID : CVE-2019-10218 CVE-2019-14833 CVE-2019-14847 CVE-2019-14861 CVE-2019-14870 CVE-2019-14902 CVE-2019-14907 CVE-2021-20254 Debian Bug : 946786 Several vulnerabilities were discovered in Samba, SMB/CIFS file, print, and login server for Unix CVE-2019-10218 A flaw was found in the samba client, where a malicious server can supply a pathname to the client with separators. This could allow the client to access files and folders outside of the SMB network pathnames. An attacker could use this vulnerability to create files outside of the current working directory using the privileges of the client user. CVE-2019-14833 A flaw was found in Samba, in the way it handles a user password change or a new password for a samba user. The Samba Active Directory Domain Controller can be configured to use a custom script to check for password complexity. This configuration can fail to verify password complexity when non-ASCII characters are used in the password, which could lead to weak passwords being set for samba users, making it vulnerable to dictionary attacks. CVE-2019-14847 A flaw was found in samba where an attacker can crash AD DC LDAP server via dirsync resulting in denial of service. Privilege escalation is not possible with this issue. CVE-2019-14861 Samba have an issue, where the (poorly named) dnsserver RPC pipe provides administrative facilities to modify DNS records and zones. Samba, when acting as an AD DC, stores DNS records in LDAP. In AD, the default permissions on the DNS partition allow creation of new records by authenticated users. This is used for example to allow machines to self-register in DNS. If a DNS record was created that case-insensitively matched the name of the zone, the ldb_qsort() and dns_name_compare() routines could be confused into reading memory prior to the list of DNS entries when responding to DnssrvEnumRecords() or DnssrvEnumRecords2() and so following invalid memory as a pointer. CVE-2019-14870 Samba have an issue, where the S4U (MS-SFU) Kerberos delegation model includes a feature allowing for a subset of clients to be opted out of constrained delegation in any way, either S4U2Self or regular Kerberos authentication, by forcing all tickets for these clients to be non-forwardable. In AD this is implemented by a user attribute delegation_not_allowed (aka not-delegated), which translates to disallow-forwardable. However the Samba AD DC does not do that for S4U2Self and does set the forwardable flag even if the impersonated client has the not-delegated flag set. CVE-2019-14902 There is an issue in samba, where the removal of the right to create or modify a subtree would not automatically be taken away on all domain controllers. CVE-2019-14907 samba have an issue where if it is set with "log level = 3" (or above) then the string obtained from the client, after a failed character conversion, is printed. Such strings can be provided during the NTLMSSP authentication exchange. In the Samba AD DC in particular, this may cause a long-lived process(such as the RPC server) to terminate. (In the file server case, the most likely target, smbd, operates as process-per-client and so a crash there is harmless). CVE-2021-20254 A flaw was found in samba. The Samba smbd file server must map Windows group identities (SIDs) into unix group ids (gids). The code that performs this had a flaw that could allow it to read data beyond the end of the array in the case where a negative cache entry had been added to the mapping cache. This could cause the calling code to return those values into the process token that stores the group membership for a user. The highest threat from this vulnerability is to data confidentiality and integrity. For Debian 9 stretch, these problems have been fixed in version 2:4.5.16+dfsg-1+deb9u4. We recommend that you upgrade your samba packages. For the detailed security status of samba please refer to its security tracker page at: https://security-tracker.debian.org/tracker/samba Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS - -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE7xPqJqaY/zX9fJAuhj1N8u2cKO8FAmCyIV8ACgkQhj1N8u2c KO8R+w/8D5KCXY/rQ/qVU7c3FdqZfs6m3TjASLDiYS2MxtIVfffAUW0ldCcP5R6t TjydCQ9loDELHeRljQtwzcFVfxp8bhkJDw2RA+qE/k7R2kM65z+w7d0DFIFJPAtj 3qWdd342PxHGVnxNLkc9e48UatVXt9r7tHGCxfUqmgCS14PFTGvMsvpl8zuH2uUC 3bosWK6GVgi9VCVfMPHfEKDjT+Ya3TsoG5agWul3FvP8uLSGU/N6gQI9s5hlS2be n5+Y5ip5uYwoIIqTVa7k5ZzaRafg9HNot+WnfdyKler3d+i5YdtDUBbTaf5lPmAx LKYwPkBKTRKzm+2tdg1tW0lqwoWXFDyefFXguIoJj3nIRCNcUyhA2xLdhaLSD79t 3ZR3yyLmfgH+KqjJtQI7K4QQNMHfr3HC689JydCxvcXmeJSZoLt1YsYGHb/LnRGM k8RCGw14AnxUm2MLXVupsehaMVxYefZTh5UX1OmU355KlgVficiMCBSDf4XyNezp GVUKa7Bh4uRyzFO3/bLupT+X1pI+cfYVoadZZpYu9NxtS40+T0AW+FxspfDPrmNL wyLlQcxZ2FlmyI4O5tDBdExrqgOqfHQ1SGajcyFyVvRwbTR+A+2QNJ8D2uN9X2Yr onxlfO8Aa+lgO/WSuwmSwcLZG/0qGS1SDwnhv3MsFBtpW5NwCt8= =2Zbt - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. 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