Ultr@VNC error buffer overflow
| untr@vnc-error-bo (25648) |  High Risk |
Description:
Ultr@VNC (UltraVNC) is vulnerable to a buffer overflow, caused by improper bounds checking of the Log::ReallyPrint() function when logging replies received from a VNC server during login. By sending an overly long string in an error response, a remote attacker in control of the VNC server could overflow a buffer and execute arbitrary code on the system.
Note: An administrative user must have changed the default "Log debug infos to the WinVNC.log file" setting in the configuration for this vulnerability to exist. However, if the setting is changed back to the default settings, this vulnerability will still be exploitable.
*CVSS:
| Base Score: | 6 |
| Access Vector: | Remote |
| Access Complexity: | Low |
| Authentication: | Required |
| Confidentiality Impact: | Complete |
| Integrity Impact: | Complete |
| Availability Impact: | Complete |
| Temporal Score: | 5 |
| Exploitability: | Functional |
| Remediation Level: | Official-Fix |
| Report Confidence: | Confirmed |
Consequences:
Gain Access
Remedy:
Upgrade to the latest version of Ultr@VNC (1.0.2 or later), available from the Ultr@VNC Web site. See References.
References:
- Full-Disclosure Mailing List Tue Apr 04 2006 - 14:24:13 CDT: Buffer-overflow in Ultr@VNC 1.0.1 viewer and server.
- Ultr@VNC Web site: Ultr@VNC.
- BID-17378: UltraVNC Multiple Remote Error Logging Buffer Overflow Vulnerabilities
- CVE-2006-1652: Multiple buffer overflows in (a) UltraVNC (aka Ultr@VNC) 1.0.1 and earlier and (b) tabbed_viewer 1.29 (1) allow user-assisted remote attackers to execute arbitrary code via a malicious server that sends a long string to a client that connects on TCP port 5900, which triggers an overflow in Log::ReallyPrint; and (2) allow remote attackers to cause a denial of service (server crash) via a long HTTP GET request to TCP port 5800, which triggers an overflow in VNCLog::ReallyPrint.
- SA19513: Ultr@VNC Buffer Overflow Vulnerabilities
- VUPEN/ADV-2006-1240: Ultr@VNC ReallyPrint() Function Remote Buffer Overflow Vulnerabilities
Platforms Affected:
- Ultr@VNC Ultr@VNC 1.0.0 RC11
Reported:
Apr 05, 2006
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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.