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Vulnerability Alert

Cisco ASA Adaptive Security Appliance Software and Cisco ASA Services Module Software DHCP Memory Allocation Denial of Service Vulnerability

 
Threat Type:CWE-119: Buffer Errors
IntelliShield ID:27104
Version:1
First Published:2012 October 10 16:12 GMT
Last Published:2012 October 10 16:12 GMT
Port: Not available
CVE:CVE-2012-4643
Urgency:Unlikely Use
Credibility:Confirmed
Severity:Mild Damage
CVSS Base:7.1 CVSS Calculator
CVSS Version 2.0
CVSS Temporal:5.9
 
Version Summary:Cisco ASA Adaptive Security Appliance Software and Cisco ASA Services Module Software contain a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition on a targeted device. Updates are available.
 
 
Description
Cisco ASA Adaptive Security Appliance (ASA) Software and Cisco ASA Services Module (ASASM) Software contain a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.

The vulnerability exists because the affected software performs improper memory operations when handling crafted DHCP packets. An unauthenticated, remote attacker could exploit this vulnerability by sending malicious DHCP traffic to the affected device. Successful exploitation could allow the attacker to cause the targeted device to reload. Sustained attacks could result in a DoS condition.

Cisco has confirmed the vulnerability in a security advisory and released software updates.
 
Warning Indicators
Cisco ASA Software and Cisco ASASM Software Releases prior to the following are vulnerable:
  • 7.2(5.8)
  • 8.0(5.28)
  • 8.1(2.56)
  • 8.2(5.27)
  • 8.3(2.30)
  • 8.4(3.10)
  • 8.5(1.8)
  • 8.6(1.4)
 
IntelliShield Analysis
To exploit the vulnerability, the attacker must send malicious requests to the targeted system, which would likely require the attacker to have access to trusted internal networks. This access requirement limits 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.

By default, DHCP server is enabled on the inside interface of the Cisco ASA 5505 and on the management interface of all other Cisco ASA 5500 Series Adaptive Security Appliances. DHCP server is disabled by default on Cisco Catalyst 6500 Series ASA Services Module.

DHCP relay feature is not enabled by default on any Cisco ASA 5500 Series Adaptive Security Appliances and Cisco Catalyst 6500 Series ASA Services Module platforms.

DHCP relay and DHCP server features will trigger the DHCP request packet process.
 
Vendor Announcements
Cisco has released a security advisory for bug ID CSCtw84068 at the following link: cisco-sa-20121010-asa
 
Impact
An unauthenticated, remote attacker could exploit this vulnerability to cause the targeted device to reload. Sustained attacks could result in a DoS condition.
 
Technical Information
The vulnerability is due to improper memory operations during the DHCP request packet process. When the affected software attempts to allocate memory for an internal DHCP data structure, a memory error condition could cause the targeted device to reload.

An unauthenticated, remote attacker could exploit this vulnerability by sending crafted DCHP packets to the affected device. When the affected software processes the malicious DHCP traffic, a memory error condition could allow the attacker to cause the targeted device to reload. Sustained attacks could result in a DoS condition.
 
Safeguards
Administrators are advised to apply the appropriate updates.

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

Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.

Administrators can help protect affected systems from external attacks by using a solid firewall strategy.

Administrators are advised to monitor critical systems.
 
Patches/Software
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via e-mail at tac@cisco.com.
 
Alert History
 
Initial Release


Product Sets
 
The security vulnerability applies to the following combinations of products.

Primary Products:
CiscoCisco Adaptive Security Appliances Firmware (ASA) 7.0 Base, .1.4, .1, .2, .3, .4, .4.2, .5, .5.12, .6, .6.4, .6.8, .6.18, .6.22, .6.26, .6.29, .6.32, .7, .7.1, .7.4, .7.9, .7.12, .8, .8.2, .8.8, .8.12, .8.13 | 7.1 .2, .2.16, .2.20, .2.24, .2.28, .2.38, .2.42, .2.46, .2.49, .2.53, .2.61, .2.64, .2.72, .2.81 | 7.2 .1, .1.9, .1.13, .1.19, .1.24, .2, .2.6, .2.10, .2.14, .2.18, .2.19, .2.22, .2.34, .3, .3.1, .3.12, .3.16, .4, .4.6, .4.9, .4.18, .4.25, .4.27, .4.30, .4.33, .5, .5.2, .5.4, .5.7 | 8.0 .1.2, .2, .2.11, .2.15, .3, .3.6, .3.12, .3.19, .4, .4.3, .4.9, .4.16, .4.23, .4.25, .4.28, .4.31, .4.32, .4.33, .5, .5.20, .5.23, .5.25, .5.27 | 8.1 Base, .1, .1.6, .2, .2.13, .2.15, .2.16, .2.19, .2.23, .2.24, .2.49, .2.50, .2.55 | 8.2 .0.45, .1, .1.11, .2, .2.9, .2.10, .2.12, .2.16, .2.17, .3, .4, .4.1, .4.4, .5, .5.13, .5.22, .5.26 | 8.3 .1, .1.1, .1.4, .1.6, .2, .2.4, .2.13, .2.23, .2.25 | 8.4 Base, .1, .1.3, .1.11, .2, .2.8, .3, .3.8, .3.9 | 8.5 Base, .1, .1.1, .1.6, .1.7 | 8.6 Base, .1, .1.1, .1.2

Associated Products:
N/A




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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.
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