OpenSSH signal handler denial of service
| openssh-signalhandler-dos (45202) |  Medium Risk |
Description:
OpenSSH is vulnerable to a denial of service, caused by the use of functions that are not async-signal-safe by the signal handler. A remote attacker could exploit this vulnerability to cause many processes to freeze, resulting in a denial of service.
*CVSS:
| Base Score: | 5 |
| Access Vector: | Network |
| Access Complexity: | Low |
| Authentication: | None |
| Confidentiality Impact: | None |
| Integrity Impact: | None |
| Availability Impact: | Partial |
| Temporal Score: | 3.7 |
| Exploitability: | Unproven |
| Remediation Level: | Official-Fix |
| Report Confidence: | Confirmed |
Consequences:
Denial of Service
Remedy:
Upgrade to the latest version of OpenSSH (4.3p2-9etch3 or later), available from the OpenSSH Web site. See References.
References:
- Debian Bug report logs - #498678: sigdie must not be called from a signal handler context.
- OpenSSH Web site: OpenSSH.
- CVE-2008-4109: A certain Debian patch for OpenSSH before 4.3p2-9etch3 on etch; before 4.6p1-1 on sid and lenny; and on other distributions such as SUSE uses functions that are not async-signal-safe in the signal handler for login timeouts, which allows remote attackers to cause a denial of service (connection slot exhaustion) via multiple login attempts. NOTE: this issue exists because of an incorrect fix for CVE-2006-5051.
- DSA-1638: openssh -- denial of service
- SECTRACK ID: 1020891: OpenSSH on Debian Lets Remote Users Prevent Logins
- SUSE-SR:2008:020: SUSE Security Summary Report
- USN-649-1: OpenSSH vulnerabilities
Platforms Affected:
- Canonical Ubuntu 6.06 LTS
- Canonical Ubuntu 7.04
- Canonical Ubuntu 7.10
- Debian Debian Linux 4.0
- OpenSSH OpenSSH
Reported:
Sep 12, 2008
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The information within this database may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. In no event shall IBM be held liable for any damages whatsoever arising out of or in connection with the use or spread of this information.