[SECURITY-L] CAIS-Alerta: Denial of Service no servico RPC da Microsoft

Qua Out 15 09:46:34 -03 2003

----- Forwarded message from Centro de Atendimento a Incidentes de Seguranca <cais em cais.rnp.br> -----

From: Centro de Atendimento a Incidentes de Seguranca <cais em cais.rnp.br>
Subject: CAIS-Alerta: Denial of Service no servico RPC da Microsoft
To: rnp-alerta em cais.rnp.br, rnp-seg em cais.rnp.br
Date: Tue, 14 Oct 2003 17:01:10 -0300 (BRST)

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Prezados,

O CAIS esta' repassando o Internet Security Systems Brief, "Microsoft RPC
Race Condition Denial of Service", que trata de uma falha existente no
servico RPC do Windows, que pode permitir a um atacante remoto conduzir um
ataque de negacao de servico contra hosts vulneraveis.

Esta vulnerabilidade esta' presente ate' mesmo nos sistemas atualizados
com todas as correcoes sugeridas pelo alerta do CAIS "Vulnerabilidades
múltiplas no serviço RPCSS (824146)", disponivel em:

	http://www.rnp.br/cais/alertas/2003/MS03-039.html

O CAIS ja' tomou conhecimento da existencia de um codigo malicioso que
explora essa vulnerabilidade. Segue abaixo a assinatura MD5 do referido
codigo malicioso:

	27a94d87f8337a722d1563d34802b379  rpc3.zip

	. conteudo do arquivo rpc3.zip:

	794eb220b9c3fc6775b08dd9425c24b0  bshell2
	03153221293aa3465b5009d9f7dd60a0  rpc3.exe
	ecd9669142d9333fe41ed52fdbdecff6  rpcdcom3.c

Sistemas afetados

	. Microsoft Windows 2000
	. Microsoft Windows XP

Identificador CVE: CAN-2003-0813
                   (http://cve.mitre.org)

Maiores informacoes podem ser obtidas atraves da seguinte url:

	http://xforce.iss.net/xforce/alerts/id/155

O CAIS relembra aos administradores e usuarios a necessidade de manterem
seus sistemas e aplicativos sempre atualizados, de acordo com as
informacoes e correcoes disponibilizadas pelos respectivos fabricantes.
Vale ressaltar a importancia de manter um anti-virus instalado e
atualizado.

Finalmente, como a questao tratada neste alerta ainda nao possui solucao
conhecida, o CAIS estara acompanhando o desenrolar do assunto, mantendo-os
informados a respeito.

Atenciosamente,

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Internet Security Systems Security Brief
October 14, 2003

Microsoft RPC Race Condition Denial of Service

Synopsis:

ISS X-Force has discovered a flaw in the Microsoft RPC service during a
routine audit that may allow remote attackers to trigger a Denial of
Service (DoS) condition on vulnerable hosts. This vulnerability exists in
the most current patch-levels of the Windows operating systems, including
computers patched against the issues described in Microsoft Security
Bulletin MS03-039. This vulnerability has been reported by various sources
as a new exploit vector against the vulnerability disclosed in MS03-039.
This assessment is incorrect. The vulnerability described in this Advisory
manifests as a result of a separate multi-threaded race condition when
processing incoming RPC requests.

Impact:

X-Force has demonstrated that a DoS vulnerability exists by exploiting the
race condition. Attackers can take advantage of this vulnerability by
crashing the Microsoft RPC service, and/or forcing vulnerable systems to
reboot. X-Force has not demonstrated that this vulnerability can be used
to execute arbitrary code or to compromise a vulnerable system.
Significant  barriers exist which may prevent reliable exploitation
outside of controlled lab conditions.

Affected Versions:

Microsoft Windows 2000
Microsoft Windows XP

For the complete ISS X-Force Security Advisory, please visit:
http://xforce.iss.net/xforce/alerts/id/155

______

About Internet Security Systems (ISS)
Founded in 1994, Internet Security Systems (ISS) (Nasdaq: ISSX) is a
pioneer and world leader in software and services that protect critical
online resources from an ever-changing spectrum of threats and misuse.
Internet Security Systems is headquartered in Atlanta, GA, with
additional operations throughout the Americas, Asia, Australia, Europe
and the Middle East.

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Use of this information constitutes acceptance for use in an AS IS
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