CVE-2016-0777
Find out more about CVE-2016-0777 from the MITRE CVE dictionary dictionary and NIST NVD.
Statement
This issue does not affect the version OpenSSH as shipped with Red Hat Enterprise Linux 4, 5 and 6. This issue affects the version of OpenSSH as shipped with Red Hat Enterprise Linux 7 in a non-default configuration. For more information please refer to https://access.redhat.com/articles/2123781
CVSS v2 metrics
| Base Score | 4.3 |
|---|---|
| Base Metrics | AV:N/AC:M/Au:N/C:P/I:N/A:N |
| Access Vector | Network |
| Access Complexity | Medium |
| Authentication | None |
| Confidentiality Impact | Partial |
| Integrity Impact | None |
| Availability Impact | None |
Find out more about Red Hat support for the Common Vulnerability Scoring System (CVSS).
Red Hat Security Errata
| Platform | Errata | Release Date |
|---|---|---|
| Red Hat Enterprise Linux 7 (openssh) | RHSA-2016:0043 | 2016-01-14 |
Affected Packages State
| Platform | Package | State |
|---|---|---|
| Red Hat Enterprise Linux 6 | openssh | Not affected |
| Red Hat Enterprise Linux 5 | openssh | Not affected |
| Red Hat Enterprise Linux 4 | openssh | Not affected |
Acknowledgements
Red Hat would like to thank Qualys for reporting this issue.Mitigation
1. The vulnerable roaming code can be permanently disabled by adding the
undocumented option "UseRoaming no" to the system-wide configuration
file (usually /etc/ssh/ssh_config), or per-user configuration file
(~/.ssh/config), or command-line (-o "UseRoaming no").
2. If an OpenSSH client is disconnected from an SSH server that offers
roaming, it prints "[connection suspended, press return to resume]" on
stderr, and waits for '\n' or '\r' on stdin (and not on the controlling
terminal) before it reconnects to the server; advanced users may become
suspicious and press Control-C or Control-Z instead, thus avoiding the
information leak.
However, SSH commands that use the local stdin to transfer data to the
remote server are bound to trigger this reconnection automatically (upon
reading a '\n' or '\r' from stdin). Moreover, these non-interactive SSH
commands (for example, backup scripts and cron jobs) commonly employ
public-key authentication and are therefore perfect targets for this
information leak.