IBM SECURITY ADVISORY First Issued: Tue Nov 14 09:46:19 CST 2017 The most recent version of this document is available here: http://aix.software.ibm.com/aix/efixes/security/openssh_advisory11.asc https://aix.software.ibm.com/aix/efixes/security/openssh_advisory11.asc ftp://aix.software.ibm.com/aix/efixes/security/openssh_advisory11.asc Security Bulletin: Vulnerability in OpenSSH affects AIX (CVE-2017-15906) =============================================================================== SUMMARY: Vulnerability in OpenSSH affects AIX. =============================================================================== VULNERABILITY DETAILS: CVEID: CVE-2017-15906 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-15906 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-15906 DESCRIPTION: The process_open function in sftp-server.c in OpenSSH does not properly prevent write operations in readonly mode, which allows attackers to create zero-length files. CVSS Base Score: 6.5 CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/133128 for the current score. CVSS Environmental Score*: Undefined CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) AFFECTED PRODUCTS AND VERSION: AIX 5.3, 6.1, 7.1, 7.2 VIOS 2.2.x The following fileset levels are vulnerable: key_fileset = osrcaix Fileset Lower Level Upper Level KEY ------------------------------------------------------------- openssh.base.client 4.0.0.5200 7.1.102.1100 key_w_fs openssh.base.server 4.0.0.5200 7.1.102.1100 key_w_fs Note: To determine if your system is vulnerable, execute the following commands: lslpp -L | grep -i openssh.base.client lslpp -L | grep -i openssh.base.server REMEDIATION: FIXES A fix is available, and it can be downloaded from https://www-01.ibm.com/marketing/iwm/iwm/web/reg/download.do?source=aixbp&lang=en_US&S_PKG=openssh&cp=UTF-8 To extract the fixes from the tar file: For Openssh 7.5 version - zcat openssh-7.5.102.1100.tar.Z | tar xvf Please refer to the Readme file to be aware of the changes that are part of the release. IMPORTANT: If possible, it is recommended that a mksysb backup of the system be created. Verify it is both bootable and readable before proceeding. Note that all the previously reported security vulnerability fixes are also included in above mentioned fileset level. Please refer to the readme file (provided along with the fileset) for the complete list of vulnerabilities fixed. To preview the fix installation: installp -apYd . openssh To install the fix package: installp -aXYd . openssh Published advisory OpenSSH signature file location: http://aix.software.ibm.com/aix/efixes/security/openssh_advisory11.asc.sig https://aix.software.ibm.com/aix/efixes/security/openssh_advisory11.asc.sig ftp://aix.software.ibm.com/aix/efixes/security/openssh_advisory11.asc.sig openssl dgst -sha1 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file] openssl dgst -sha1 -verify [pubkey_file] -signature [ifix_file].sig [ifix_file] WORKAROUNDS AND MITIGATIONS: None. =============================================================================== CONTACT US: If you would like to receive AIX Security Advisories via email, please visit "My Notifications": http://www.ibm.com/support/mynotifications https://www.ibm.com/support/mynotifications To view previously issued advisories, please visit: http://www14.software.ibm.com/webapp/set2/subscriptions/onvdq https://www14.software.ibm.com/webapp/set2/subscriptions/onvdq Contact IBM Support for questions related to this announcement: http://ibm.com/support/ https://ibm.com/support/ To obtain the OpenSSL public key that can be used to verify the signed advisories and ifixes: Download the key from our web page: http://www.ibm.com/systems/resources/systems_p_os_aix_security_pubkey.txt https://www.ibm.com/systems/resources/systems_p_os_aix_security_pubkey.txt To obtain the PGP public key that can be used to communicate securely with the AIX Security Team via security-alert@austin.ibm.com you can either: A. Download the key from our web page: http://www.ibm.com/systems/resources/systems_p_os_aix_security_pgppubkey.txt B. Download the key from a PGP Public Key Server. The key ID is: 0x28BFAA12 Please contact your local IBM AIX support center for any assistance. REFERENCES: Complete CVSS v3 Guide: http://www.first.org/cvss/user-guide https://www.first.org/cvss/user-guide On-line Calculator v3: http://www.first.org/cvss/calculator/3.0 https://www.first.org/cvss/calculator/3.0 ACKNOWLEDGEMENTS: None CHANGE HISTORY: First Issued: Tue Nov 14 09:46:19 CST 2017 =============================================================================== *The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Flash. Note: According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES "AS IS" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY.