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ESB-2015.2550 - [Cisco] Cisco Email Security Appliance: Denial of service - Existing account

Date: 06 October 2015

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2015.2550
 Cisco Email Security Appliance Max Files Denial of Service Vulnerability
                              6 October 2015

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Cisco Email Security Appliance
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Denial of Service -- Existing Account
Resolution:        Mitigation
CVE Names:         CVE-2015-6309  

Original Bulletin: 
   http://tools.cisco.com/security/center/mviewAlert.x?alertId=41241

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Vulnerability Alert

Cisco Email Security Appliance Max Files Denial of Service Vulnerability

Threat Type: CWE-399: Resource Management Errors

IntelliShield ID: 41241 Version: 1

First Published: 2015 September 30 18:56 GMT Last Published: 2015 September 30
18:56 GMT

Vector: Low

Authentication: Single

Exploit: Functional

CVE: CVE-2015-6309

Urgency: 2

Credibility: 5

Severity: 3

CVSS Base: 6.8

CVSS Temporal: 6.5

Version Summary:

Cisco Email Security Appliance contains a vulnerability that could allow an 
authenticated, remote attacker to cause a denial of service condition. Updates
are not available.

Aliases/Variants None Virus Name: None Description:

A vulnerability in file descriptor handling of the Cisco Email Security 
Appliance (ESA) could allow an authenticated, remote attacker to cause a 
denial of service (DoS) condition due to the affected device unexpectedly 
reloading.

The vulnerability is due to failure to release file descriptors when the 
requested file action is completed. An attacker could exploit this 
vulnerability by sending a crafted HTTP request to the affected device. A 
successful exploit could allow the attacker to cause a DoS condition due to 
the affected device failing to release file descriptors. When all file 
descriptors are in use, the device can reload unexpectedly.

Cisco has confirmed the vulnerability; however, software updates are not 
available.

    Impact

    An authenticated, remote attacker could exploit this vulnerability to 
    cause an affected device to reload unexpectedly, resulting in a DoS condition.

    Warning Indicators

    At the time this alert was first published, Cisco ESA releases 8.5.6-106 
    and 9.6.0-042 were vulnerable. Later releases of Cisco ESA may also be 
    vulnerable.

    Technical Information

    The vulnerability is due to improper handling of file descriptors after 
    the completion of a requested file action by an affected device.

    An authenticated, remote attacker could exploit this vulnerability by 
    sending a crafted HTTP request to the affected device. A successful exploit 
    could cause the affected device to fail to release file descriptors, which 
    could cause the device to unexpectedly reload, resulting in a DoS condition.

    Vendor Announcements

    Cisco has released bug ID CSCuw32211 for registered users, which contains
    additional details and an up-to-date list of affected product versions.

    IntelliShield Analysis

    To exploit this vulnerability, an attacker must authenticate to the 
    targeted device. This access requirement reduces the likelihood of a 
    successful exploit.

    Cisco indicates through the CVSS score that functional exploit code 
    exists; however, the code is not known to be publicly available.

    Safeguards

    Administrators are advised to contact the vendor regarding future updates
    and releases.

    Administrators are advised to allow only trusted users to have network 
    access.

    Administrators are advised to allow only privileged users to access 
    administration or management systems.

    Administrators are advised to monitor affected systems.

    Patches/Software

    Software updates are not available.

    Primary Product Set (1)

LEGAL DISCLAIMER

The urgency and severity ratings of this alert are not tailored to 
individual users; users may value alerts differently based upon their network
configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED 
THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF 
GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED 
THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION
IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE
TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES 
THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.

- --------------------------END INCLUDED TEXT--------------------

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===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
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                On call after hours for member emergencies only.
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