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Vulnerability of Windows: code execution via the SMB server

Synthesis of the vulnerability 

An attacker can connect to the SMB/CIFS server, in order to generate a denial of service or to execute code on the computer.
Impacted software: Windows 2000, Windows 2003, Windows 2008 R0, Windows 2008 R2, Windows 7, Windows Vista, Windows XP.
Severity of this computer vulnerability: 3/4.
Number of vulnerabilities in this bulletin: 4.
Creation date: 10/02/2010.
Revision date: 18/10/2010.
Références of this announce: 971468, BID-38049, BID-38051, BID-38054, BID-38085, CERTA-2010-AVI-070, CVE-2010-0020, CVE-2010-0021, CVE-2010-0022, CVE-2010-0231, MS10-012, VIGILANCE-VUL-9436.

Description of the vulnerability 

The SMB/CIFS service of Windows is impacted by four vulnerabilities.

An authenticated attacker can send a SMB packet containing a long path, generating a buffer overflow, and leading to code execution with system privileges. [severity:3/4; BID-38049, CERTA-2010-AVI-070, CVE-2010-0020]

An attacker can send a malformed packet during the negotiate phase, in order to block the service. [severity:2/4; BID-38054, CVE-2010-0021]

An attacker can send a SMB packet with an empty share name or server name, in order to generate a NULL pointer dereference, which stops the service. [severity:2/4; BID-38051, CVE-2010-0022]

The server uses a challenge of 8 bytes, which is not sufficiently random. An attacker can therefore use a brute force attack to authenticate. [severity:3/4; BID-38085, CVE-2010-0231]

An attacker can therefore connect to the SMB/CIFS server, in order to generate a denial of service or to execute code on the computer.
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This cybersecurity vulnerability impacts software or systems such as Windows 2000, Windows 2003, Windows 2008 R0, Windows 2008 R2, Windows 7, Windows Vista, Windows XP.

Our Vigil@nce team determined that the severity of this vulnerability is important.

The trust level is of type confirmed by the editor, with an origin of intranet client.

This bulletin is about 4 vulnerabilities.

A proof of concept or an attack tool is available, so your teams have to process this alert. An attacker with a technician ability can exploit this weakness alert.

Solutions for this threat 

Windows: patch for the SMB server.
The Microsoft announce indicates patches and workarounds.
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