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vulnerability bulletin 8683

Trend Micro: bypassing via RAR, CAB and ZIP

Synthesis of the vulnerability

An attacker can create a RAR, CAB or ZIP archive containing a virus which is not detected by Trend Micro.
Vulnerable software: TrendMicro Internet Security, InterScan Messaging Security Suite, InterScan Web Security Suite, ScanMail, TrendMicro ServerProtect.
Severity of this announce: 2/4.
Consequences of an intrusion: data flow.
Attacker's origin: document.
Number of vulnerabilities in this bulletin: 3.
Creation date: 30/04/2009.
Références of this computer vulnerability: BID-34763, TZO-17-2009, VIGILANCE-VUL-8683.

Description of the vulnerability

Trend Micro products detect viruses contained in RAR, CAB and ZIP archives.

However, an attacker can create a slightly malformed archive, which can still be opened by Unrar/Unzip tools, but which cannot be opened by the antivirus.

Depending on Trend Micro product, these archives are handled in three ways:

OfficeScan and ServerProtect are vulnerable when Unrar/Unzip extracts the file on the desktop computer. These products are thus vulnerable when installed on a scan server. [severity:2/4]

InterScan Web Security Suite and InterScan Messaging Security quarantine the file by default. These products are vulnerable if the administrator changed the default configuration. [severity:2/4]

ScanMail does not indicate that the unscanned archive potentially contains a virus. This product is vulnerable in its default configuration. [severity:2/4]

An attacker can therefore create a RAR, CAB or ZIP archive containing a virus which is not detected by Trend Micro.
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