Multiple vulnerabilities in OpenSSH
| Risk | Medium |
| Patch available | YES |
| Number of vulnerabilities | 5 |
| CVE-ID | CVE-2016-6210 CVE-2016-6515 CVE-2015-8325 |
| CWE-ID | CWE-200 CWE-400 CWE-264 |
| Exploitation vector | Network |
| Public exploit |
Public exploit code for vulnerability #1 is available. Public exploit code for vulnerability #4 is available. |
| Vulnerable software Subscribe |
OpenSSH Server applications / Remote management servers, RDP, SSH |
| Vendor | OpenSSH |
Security Bulletin
This security bulletin contains information about 5 vulnerabilities.
1) User enumeration via covert timing channel
EUVDB-ID: #VU255
Risk: Medium
CVSSv3.1: 4.9 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:F/RL:O/RC:C]
CVE-ID: CVE-2016-6210
CWE-ID:
CWE-200 - Information exposure
Exploit availability: Yes
DescriptionThe vulnerability allows a remote attacker to enumerate users on system.
The vulnerability exists in most systems where the Blowfish algorithm runs faster than SHA256/SHA512. A remote unauthenticated attacker can determine valid usernames by sending a specially crafted request with a large password (approximately 10,000 characters) to the target ssh daemon. On systems where a valid user's password has been hashed with SHA256/SHA512, the response time will be shorter for a non-existent username than for a valid username.
Successful exploitation of this vulnerability may result in disclosure or user logins.
MitigationInstall the latest version of OpenSSH 7.3.
Vulnerable software versionsOpenSSH: 6.0p1 - 7.2p2
External linkshttp://www.openssh.com/txt/release-7.3
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
How the attacker can exploit this vulnerability?
The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability. However, a fully functional exploit for this vulnerability is available.
2) Disclosure of potentially sensitive timing information
EUVDB-ID: #VU254
Risk: Low
CVSSv3.1: 4.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]
CVE-ID: N/A
CWE-ID:
CWE-200 - Information exposure
Exploit availability: No
DescriptionThe vulnerability allows a remote attacker to obtain potentially sensitive timing information.
The vulnerability exists in OpenSSH. A remote attacker can detect timing differences in the ssh(1) and sshd(8) MAC verification for Encrypt-then-MAC (EtM) mode transport MAC algorithms.
Successful exploitation of this vulnerability may result in disclosure of system information.
MitigationInstall the latest version of OpenSSH 7.3.
Vulnerable software versionsOpenSSH: 7.0p1 - 7.2p2
External linkshttp://www.openssh.com/txt/release-7.3
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
How the attacker can exploit this vulnerability?
The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
3) Sensitive timing information disclosure
EUVDB-ID: #VU253
Risk: Low
CVSSv3.1: 4.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]
CVE-ID: N/A
CWE-ID:
CWE-200 - Information exposure
Exploit availability: No
DescriptionThe vulnerability allows a remote attacker to obtain potentially sensitive timing information.
The vulnerability exists in OpenSSH. A remote attacker may be able to observe timing differences in the ssh(1) and sshd(8) CBC padding oracle countermeasures.
Successful exploitation of this vulnerability may result in disclosure of system information.
Mitigation
Install the latest version of OpenSSH 7.3.
Vulnerable software versionsOpenSSH: 7.0p1 - 7.2p2
External linkshttp://www.openssh.com/txt/release-7.3
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
How the attacker can exploit this vulnerability?
The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
4) Consuming excessive CPU resources on the target system
EUVDB-ID: #VU252
Risk: Medium
CVSSv3.1: 7.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C]
CVE-ID: CVE-2016-6515
CWE-ID:
CWE-400 - Resource exhaustion
Exploit availability: Yes
DescriptionThe vulnerability allows a remote attacker to consume excessive CPU resources on the target system.
The vulnerability exists in the crypt(3) function, which accepts passwords longer that 1024 characters in auth_password() function in the auth_passwd.c . A remote unauthenticated attacker can submit a very long string as a password and consume excessive CPU resources.
Successful exploitation of this vulnerability may result in denial of service.
MitigationInstall the latest version of OpenSSH 7.3.
Vulnerable software versionsOpenSSH: 7.0p1 - 7.2p2
External linkshttp://www.openssh.com/txt/release-7.3
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
How the attacker can exploit this vulnerability?
The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.
5) Incorrect handling of environment files
EUVDB-ID: #VU251
Risk: Low
CVSSv3.1: 6.8 [CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2015-8325
CWE-ID:
CWE-264 - Permissions, Privileges, and Access Controls
Exploit availability: No
DescriptionThe vulnerability allows a local user to execute arbitrary code on the target system.
The vulnerability exists in portable version of OpenSSH. A local user can execute arbitrary code as root by setting specially crafted environment variables to conduct attacks against the 'bin/login' process on systems, where PAM is configured to read user-specified environment variables and 'sshd_config' is set to 'UseLogin=yes'.
Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.
Mitigation
Install the latest version of OpenSSH 7.3.
Vulnerable software versionsOpenSSH: 7.0p1 - 7.2p2
External linkshttp://www.openssh.com/txt/release-7.3
Q & A
Can this vulnerability be exploited remotely?
No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.
How the attacker can exploit this vulnerability?
The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.
The attacker would have to login to the system and perform certain actions in order to exploit this vulnerability.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
