An information leak flaw and buffer overflow flaw in the way the OpenSSH client roaming feature was implemented affects IBM i.
DESCRIPTION: OpenSSH could allow a remote attacker to obtain sensitive information, caused by a client information leak from using the roaming connection feature. By persuading a victim to connect to a malicious server, an attacker could exploit this vulnerability to retrieve private cryptographic keys or other sensitive information.
CVSS Base Score: 6.5
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/109635 for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N)
DESCRIPTION: OpenSSH is vulnerable to a heap-based buffer overflow, caused by improper bounds checking by the packet_write_wait() and ssh_packet_write_wait() API functions when two non-default options: a ProxyCommand and either ForwardAgent or ForwardX11are used. By persuading a victim to connect to a malicious server, a remote attacker could overflow a buffer and execute arbitrary code on the system or cause the application to crash.
CVSS Base Score: 5
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/109636 for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L)
Affected Products and Versions
Releases 6.1, 7.1 and 7.2 of IBM i are affected.
The issue can be fixed by applying a PTF to the IBM i Operating System.
Releases 6.1, 7.1 and 7.2 of IBM i are supported and will be fixed.
The IBM i PTF numbers are:
Release 6.1 – SI59305
Release 7.1 – SI59213
Release 7.2 – SI59204
After applying fix, IBM recommends that you regenerate your SSH keys as a precaution.
Important note: IBM recommends that all users running unsupported versions of affected products upgrade to supported and fixed version of affected products.
Workarounds and Mitigations
Get Notified about Future Security Bulletins
*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 Security Bulletin.
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. In addition to other efforts to address potential vulnerabilities, IBM periodically updates the record of components contained in our product offerings. As part of that effort, if IBM identifies previously unidentified packages in a product/service inventory, we address relevant vulnerabilities regardless of CVE date. Inclusion of an older CVEID does not demonstrate that the referenced product has been used by IBM since that date, nor that IBM was aware of a vulnerability as of that date. We are making clients aware of relevant vulnerabilities as we become aware of them. "Affected Products and Versions" referenced in IBM Security Bulletins are intended to be only products and versions that are supported by IBM and have not passed their end-of-support or warranty date. Thus, failure to reference unsupported or extended-support products and versions in this Security Bulletin does not constitute a determination by IBM that they are unaffected by the vulnerability. Reference to one or more unsupported versions in this Security Bulletin shall not create an obligation for IBM to provide fixes for any unsupported or extended-support products or versions.
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18 December 2019