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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Cisco security notice mentions the blaster worm possibly affectin
The answer is simple, don't use Windoes.
Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA
-----Original Message-----
Sent: Thursday, August 14, 2003 12:30 PM
To: Multiple recipients of list ORACLE-L
affectin
My network admin sent me this Cisco security notice. In this notice there is a section about how the worm can affect a windows server running Oracle 9i and Kerberos.
Here is the section from the notice that was brought to my attention:
TCP port 4444 is used for Kerberos authentication and Oracle9i
communication. A
host fully infected with the W32.Blaster worm opens a command shell on this
port, allowing the machine to be controlled remotely. Blocking this port may
prevent an infected machine from being used for further malicious
activities,
but may block existing Kerberos authentication functionality or Oracle9i
implementations within your network.
I have pasted the complete notice at the end of the message.
Bryan Rodrigues
Oracle DBA
Elcom, Inc.
[mailto:psirt_at_cisco.com]
Sent: Wednesday, August 13, 2003 10:00 PM
To: cust-security-announce_at_cisco.com
Cc: psirt_at_cisco.com
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Cisco Security Notice: W32.BLASTER Worm Mitigation Recommendations
Revision 1.0 INTERIM
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Contents
Summary
Details
Detection
Using IOS with NetFlow Enabled to Detect Infected Hosts
Using CatOS with Sup2 and MLS to Detect Infected Hosts
CSIDS Signature
Cisco CallManager, Cisco Customer Response Server, Cisco Personal Assistant, Cisco Conference Connection, Cisco Emergency Responder
Cisco Building Broadband Service Manager
Other Windows-based Cisco Products
Obtaining Fixed Software
ACL for IOS
Cisco 12000
VACL on the 6500
Catalyst 3550
Catalyst 2950
Catalyst 2900XL and 3500XL
PIX
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Summary
Cisco customers are currently experiencing attacks due to a new worm that is
active on the Internet. The signature of this worm appears as UDP traffic to
port 69 and high volumes of TCP traffic to port 135 and 4444. Affected
customers have been experiencing high volumes of traffic from both internal
and
external systems. Symptoms on Cisco devices include, but are not limited to
high CPU and traffic drops on the input interfaces. This document focuses on
both mitigation techniques and affected Cisco products which need software
supplied by Cisco to patch properly.
The worm has been referenced by the name "W32.Blaster" and "msblast.exe".
This
worm exploits a vulnerability previously disclosed by Microsoft, details of
which can be found at the following URL:
http://www.microsoft.com/technet/security/bulletin/MS03-026.asp
Details
Details of the worm can be found on Microsoft's web site:
http://www.microsoft.com/technet/security/virus/alerts/msblaster.asp
The effects of this worm can be mitigated by blocking the required ports it
uses to spread itself, scan for new infections, and propagate the executable
code. This document focuses on blocking the spread of the worm, either
before
or after your internal network is infected. This worm spreads using valid
ports, blocking those ports may break existing functionality, such as file
sharing, TFTP or Kerberos authentication. As with all network
configurations,
Cisco recommends you establish documentation of baseline traffic during
normal
times, and use that to make decisions about blocking ports or traffic in
your
network. Block ports with caution to avoid disabling functionality in your
network. Brief descriptions of the normal usage of these ports is listed
below.
TCP port 135 is used for the MS RPC protocol. This is often used to share
files
on local network segments, and rarely used to share files over WAN segments.
This is the port where the initial vulnerability is exploited, initiating a
sequence of events that fully infects a machine. Blocking port 135 can
prevent
initial infections, but may disable existing filesharing functionality
within
your network.
UDP port 69 is used for Trivial File Transport Protocol (TFTP), often used
to
load new software images or configurations to networked devices. A host
infected with the W32.Blaster worm opens up this port to transfer the
msblast.exe file from an infected machine to a newly exploited machine.
Blocking this port may prevent the spread of the worm from an already
infected
machine to vulnerable hosts, but may break existing TFTP functionality
within
your network.
TCP port 4444 is used for Kerberos authentication and Oracle9i
communication. A
host fully infected with the W32.Blaster worm opens a command shell on this
port, allowing the machine to be controlled remotely. Blocking this port may
prevent an infected machine from being used for further malicious
activities,
but may block existing Kerberos authentication functionality or Oracle9i
implementations within your network.
TCP and or UDP ports 137, 138, 139 and 593 have vulnerabilities associated
with
them and may leave hosts open to exploitation, but are not currently known
to
be directly connected to the spread of the W32.Blaster worm. Cisco
recommends
that any unneeded ports, particularly those with known vulnerabilities
associated with them, should be blocked both inbound and outbound at edge
networks to prevent their remote exploitation.
Detection
Using IOS with NetFlow Enabled to Detect Infected Hosts
NetFlow can be a powerful tool to help identify infected hosts. Netflow must
be
enabled on an interface with the command ip route-cache flow.
Router>show ip cache flow | i 0087
SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP Pkts
Fa2/0 XX.XX.XX.242 Fa1/0 XX.XX.XX.119 06 0B88 0087 1
Fa2/0 XX.XX.XX.242 Fa1/0 XX.XX.XX.169 06 0BF8 0087 1
Fa2/0 XX.XX.XX.204 Fa1/0 XX.XX.XX.63 06 0E80 0087 1
Fa2/0 XX.XX.XX.204 Fa1/0 XX.XX.XX.111 06 0CB0 0087 1
Fa2/0 XX.XX.XX.204 Fa1/0 XX.XX.XX.95 06 0CA0 0087 1
Fa2/0 XX.XX.XX.204 Fa1/0 XX.XX.XX.79 06 0C90 0087 1
Using CatOS with Sup2 and MLS to Detect Infected Hosts
NetFlow can be a powerful tool to help identify infected hosts. Netflow must
be
enabled on an interface with the command ip route-cache flow.
Router>show ip cache flow | i 0087
SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP Pkts
Fa2/0 XX.XX.XX.242 Fa1/0 XX.XX.XX.119 06 0B88 0087 1
Fa2/0 XX.XX.XX.242 Fa1/0 XX.XX.XX.169 06 0BF8 0087 1
Fa2/0 XX.XX.XX.204 Fa1/0 XX.XX.XX.63 06 0E80 0087 1
Fa2/0 XX.XX.XX.204 Fa1/0 XX.XX.XX.111 06 0CB0 0087 1
Fa2/0 XX.XX.XX.204 Fa1/0 XX.XX.XX.95 06 0CA0 0087 1
Fa2/0 XX.XX.XX.204 Fa1/0 XX.XX.XX.79 06 0C90 0087 1
CSIDS Signature
If a Cisco Secure Intrusion Detection System is in use, a signature update
file
is available here:
http://www.cisco.com/public/sw-center/ciscosecure/ids/crypto/
To reduce false positives on S49, signature 3327 should be set to only
inspect
port 135, and not 139 or 445.
Alternatively, a custom signature string can be added to address this worm. Brief instructions are included here:
Engine STRING.UDP
SigName MS Blast Worm TFTP Request
ServicePorts 69
RegexString \x00\x01[Mm][Ss][Bb][Ll][Aa][Ss][Tt][.][Ee][Xx][Ee]\x00
Direction ToService
Symptoms
For symptoms on an infected Microsoft host, please see the Microsoft
bulletin
at http://www.microsoft.com/technet/security/virus/alerts/msblaster.asp
Overall network symptoms may manifest as increased load on firewalls,
routers
and switches due to increased traffic. You may see instability in networks
due
to increased load. The traffic load generated by this worm is high, but
appears
to have stabilized after the first 24 hours of infection.
Unexplained network failures may be due to filtering or blocking legitimate
services with filters which are too generic -- if devices such as routers or
IP
phones appear to not boot, please check that they still have access to a
TFTP
server. These devices are not vulnerable to the W32.Blaster worm, but may
depend on open TFTP functionality when they boot to load software or
configuration files.
Affected Products
To determine if a product is vulnerable, review the list below. If the
software
versions or configuration information are provided, then only those
combinations are vulnerable. This is a list of appliance software which
needs
patches downloaded from Cisco.
+ BBSM Version 5.1
+ BBSM Version 5.2
+ HotSpot 1.0
Other Cisco products which run on a Microsoft based operating system should strongly consider loading the patch from Microsoft at:
http://www.microsoft.com/technet/security/bulletin/MS03-026.asp
This list is not all inclusive, please refer to Microsoft's bulletin if you think you have an affected Microsoft platform.
+ CiscoWorks VPN/Security Management Solution (CWVMS)
+ User Registration Tool
+ Lan Management Solution
+ Routed WAN Management
+ Service Management
+ VPN/Security Management Solution
+ IP Telephony Environment Monitor
+ Wireless Lan Solution Engine
+ Small Network Management Solution
+ QoS Policy Manager
+ Voice Manager
+ Cisco Secure Scanner
+ Cisco Secure Policy Manager (CSPM)
+ Access Control Server (ACS)
Software Versions and Fixes
Cisco CallManager, Cisco Customer Response Server, Cisco Personal Assistant, Cisco Conference Connection, Cisco Emergency Responder
If the operating system version is Win2000 2.4, customers should download
and
install one of the following options:
Both are available at http://www.cisco.com/pcgi-bin/tablebuild.pl/cmva-3des.
Cisco Building Broadband Service Manager
Software is now available on Cisco's website to patch BBSM 5.1, 5.2, and HotSpot 1.0.
Instructions for installing service patches on BBSM can be found here: http://www.cisco.com/univercd/cc/td/doc/product/aggr/bbsm/bbsm52/user/use52_ 05.htm#50416
Other Windows-based Cisco Products
Customers should download the Security Patch directly from Microsoft and
follow
the directions for installation:
http://www.microsoft.com/technet/security/bulletin/MS03-026.asp
Obtaining Fixed Software
Where Cisco provides the operating system bundled with the product, Cisco is offering free software patches to address these vulnerabilities for all affected customers. Customers may only install and expect support for the feature sets they have purchased.
Customers with service contracts should contact their regular update
channels
to obtain any software patch containing the feature sets they have
purchased.
For most customers with service contracts, this means that patches should be
obtained through the Software Center on Cisco's Worldwide Web site at
http://www.cisco.com/tacpage/sw-center/.
Customers whose Cisco products are provided or maintained through a prior or existing agreement with third-party support organizations such as Cisco Partners, authorized resellers, or service providers should contact that support organization for assistance with obtaining the free software patch(es).
Customers who purchased directly from Cisco but who do not hold a Cisco
service
contract, and customers who purchase through third party vendors but are
unsuccessful at obtaining fixed software through their point of sale, should
obtain fixed software by contacting the Cisco Technical Assistance Center
(TAC)
using the contact information listed below. In these cases, customers are
entitled to obtain a patch to a later version of the same release or as
indicated by the applicable row in the Software Versions and Fixes table
(noted
above).
Cisco TAC contacts are as follows:
See http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for
additional
TAC contact information, including special localized telephone numbers and
instructions and e-mail addresses for use in various languages.
Please have your product serial number available and give the URL of this notice as evidence of your entitlement to a free upgrade.
Please do not contact either "psirt_at_cisco.com" or "security-alert_at_cisco.com" for software upgrades.
Workarounds
This section is focused on mitigation techniques for the W32.Blaster worm
using
existing Cisco products in your network. These techniques should be applied
both inbound and outbound at the edge of network segments if it is
determined
they will not affect existing network functionality. Affected systems will
still be infected and able to spread within contained sections of the
network,
therefore it is recommended that all affected servers be patched according
to
Microsoft's recommendations.
Although each of these examples show how to block all affected ports, it may
not be necessary to block all ports. If you have no infected hosts within
your
network, it may be acceptable to only block port 135 at your network edge,
this
would prevent infection from outside your network without impeding existing
TFTP and Kerberos services. Using NetFlow to identify normal traffic flow on
your network will aid you in applying these mitigation techniques with the
least impact.
General information regarding strategies for protecting against Distributed Denial of Service attacks may be found at http://www.cisco.com/warp/public/707/newsflash.html.
Caution: As with any configuration change in a network, evaluate the impact of this configuration prior to applying the change.
ACL for IOS
This workaround applies to most router platforms unless a platform is
mentioned
specifically below.
Note: If you are trying to track source addresses, use Sampled NetFlow,
rather
than "log" statements in ACLs as the high traffic in combination with the
log
statement can overwhelm the router.
! --- block TFTP
access-list 115 deny udp any any eq 69
! --- block W32.Blaster related protocols
access-list 115 deny tcp any any eq 135 access-list 115 deny udp any any eq 135
! --- block other vulnerable MS protocols
access-list 115 deny udp any any eq 137
access-list 115 deny udp any any eq 138
access-list 115 deny tcp any any eq 139
access-list 115 deny udp any any eq 139
access-list 115 deny tcp any any eq 445
access-list 115 deny tcp any any eq 593
! --- block remote access due to W32.Blaster
access-list 115 deny tcp any any eq 4444
! --- Allow all other traffic -- insert ! --- other existing access-list entries here
access-list 115 permit ip any any
interface <interface>
ip access-group 115 in
ip access-group 115 out
The worm will attempt to send packets to random IP addresses, some of which
may
not exist. When that occurs, the router will reply with an "ICMP
unreachable"
packet. In some cases, replying to a large number of requests with invalid
IP
addresses may result in degradation of the router's performance. To prevent
that from occurring, use the following command:
Router(config)# interface <interface> Router(if-config)# no ip unreachables
Caution: Common network configurations, such as certain types of tunnel structures, require the use of "ip unreachables". If the router must be able to send "ICMP unreachable" packets, you can rate limit the number of replies using the following command:
Router(config)# ip icmp rate-limit unreachable <millisecond>
Beginning with Cisco IOS Software Release 12.0, the default rate limiting is set to two packets per second (500 ms), a value of 2000 ms is commonly used.
Cisco 12000
Receive ACL Feature-On a Cisco 12000 (GSR) series router, packets destined
to
the router's ip addresses are "punted" to the gigabit route processor (GRP)
for
processing. In order to protect the GRP, receive ACLs (rACLs) can be
applied.
rACLs filter traffic destined to the GRP and only traffic explicitly
permitted
is processed by the GRP, denied traffic is dropped. In general, rACLs do not
affect transit traffic (traffic flowing through a router), only traffic
destined to the router itself.
rACLs are an extremely effective countermeasure for mitigating the effects
of
excessive attack traffic destined to the GRP. For more information please
refer
to: GSR: Receive Access Control Lists.
VACL on the 6500
Cisco recommends the use of IOS ACLs on the Cisco Catalyst 4000 with a Sup3
and
Hybrid and Native configurations of the Cisco Catalyst 6500, however a VACL
configuration example is provided for your convenience. Additionally, the
use
of "no ip unreachables" is recommended.
Caution: As when making any configuration change, use caution when using VACLs in conjunction with IOS ACLs. Be aware that VACLs apply to all traffic within the VLAN, regardless of direction.
To configure:
! --- block TFTP
set security acl ip BLASTER deny udp any any eq 69
! --- block vulnerable MS protocols
! --- Blaster related
set security acl ip BLASTER deny tcp any any eq 135 set security acl ip BLASTER deny udp any any eq 135
! --- Non-blaster related
set security acl ip BLASTER deny tcp any any eq 137 set security acl ip BLASTER deny udp any any eq 137 set security acl ip BLASTER deny tcp any any eq 138 set security acl ip BLASTER deny udp any any eq 138 set security acl ip BLASTER deny tcp any any eq 139 set security acl ip BLASTER deny udp any any eq 139 set security acl ip BLASTER deny tcp any any eq 593
! --- block remote access due to W32.Blaster
set security acl ip BLASTER deny tcp any any eq 4444
! --- Allow all other traffic
! --- insert other existing access-list entries here
set security acl ip BLASTER permit any any
! -- applies both inbound and outbound
commit security acl BLASTER
set security acl map BLASTER <vlans>
To verify:
show security acl info all
To remove:
clear security acl BLASTER
commit security acl BLASTER
Catalyst 3550
Apply the IOS ACL on switch virtual interfaces (SVIs), which are Layer 3
interfaces to VLANs; on physical Layer 3 interfaces; and on Layer 3
EtherChannel interfaces in both the inbound and/or outbound direction.
Ensure
'no ip unreachable' is configured on the interface.
Apply the IOS ACL to Layer 2 interfaces on the switch only if an IOS ACL is
not
also applied to the input of a Layer 3 interface (an error message is
generated
upon attempts to do so). For Layer 2 interfaces the IOS ACL is supported on
the
physical interfaces only and not on EtherChannel interfaces. It can be
applied
on the inbound direction only.
Catalyst 2950
Apply the IOS ACL to the interface. Note that ACL's are only supported in
the
inbound direction. To apply ACLs to physical interfaces the enhanced
software
image (EI) must be installed.
Catalyst 2900XL and 3500XL
These are Layer 2 switches with no Layer 3 access list support.
PIX
The default behavior of the PIX is to block traffic from lower security
level
interfaces (OUTSIDE) to higher security level interfaces (INSIDE) unless the
affected ports and protocols have been explicitly permitted by an
access-list
or conduit.
In addition, Cisco recommends blocking traffic from higher security level interfaces (INSIDE) to lower security level interfaces (OUTSIDE).
Customers should deny outbound attempts to these ports:
access-list acl_inside deny udp any any eq 69
access-list acl_inside deny tcp any any eq 135
access-list acl_inside deny udp any any eq 135
access-list acl_inside deny tcp any any eq 137
access-list acl_inside deny udp any any eq 137
access-list acl_inside deny tcp any any eq 138
access-list acl_inside deny udp any any eq 138
access-list acl_inside deny tcp any any eq 139
access-list acl_inside deny udp any any eq 139
access-list acl_inside deny tcp any any eq 445
access-list acl_inside deny tcp any any eq 593
access-list acl_inside deny tcp any any eq 4444
! --- insert previously configured acl statements here, ! --- or permit all other traffic out
access-list acl_inside permit ip any any
access-group acl_inside in interface inside
The corresponding outbound lists may be applied, however, ACLs are strongly recommended in lieu of outbound lists.
Exploitation and Public Announcements
This issue is being exploited actively and has been discussed in numerous public announcements and messages. References include:
Status of This Notice: INTERIM
This is a DRAFT notice. Although Cisco cannot guarantee the accuracy of all statements in this notice, all of the facts have been checked to the best of our ability. Cisco anticipates issuing updated versions of this notice when there is material change in the facts.
Distribution
This notice will be posted on Cisco's worldwide website at http://www.cisco.com/warp/public/707/cisco-sn-20030814-blaster.shtml. In addition to worldwide web posting, a text version of this notice is clear-signed with the Cisco PSIRT PGP key and is posted to the following e-mail and Usenet news recipients:
Future updates of this notice, if any, will be placed on Cisco's worldwide
web.
Users concerned about this problem are encouraged to check the URL given
above
for any updates.
Revision History
+---------------------------------------------+ | Revision | 14-August-2003 | Initial Public | | 1.0 | | Release | +---------------------------------------------+
Cisco Security Procedures
If you have any new information that would be of use to us, please send
email
to psirt_at_cisco.com.
Complete information on reporting security vulnerabilities in Cisco
products,
obtaining assistance with security incidents, and registering to receive
security information from Cisco, is available on Cisco's worldwide website
at
http://www.cisco.com/warp/public/707/sec_incident_response.shtml. This
includes
instructions for press inquiries regarding Cisco security notices. All Cisco
Security Advisories are available at http://www.cisco.com/go/psirt/.
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Related Information
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--
Please see the official ORACLE-L FAQ: http://www.orafaq.net
--
Author: Rodrigues, Bryan
INET: BRodrigues_at_elcom.com
Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting servicesto: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
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