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SANS ISC: InfoSec Handlers Diary Blog - Internet Storm Center Diary 2014-08-12 InfoSec Handlers Diary Blog


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Something is amiss with the Interwebs! BGP is a flapping.

Published: 2014-08-12
Last Updated: 2014-08-13 13:28:54 UTC
by Adrien de Beaupre (Version: 1)
2 comment(s)

[Update] See http://www.bgpmon.net/what-caused-todays-internet-hiccup/ for a good summary of what happened.

 

Tuesday Morning, various networks experienced outages from 4-6am EDT (8-10am UTC) [1]. I appears the outage was the result of a somewhat anticipated problem with older routers and their inability to deal with the ever increasing size of the Internet's routing table.

These BGP routers need to store a map of the internet defining which IP address range belongs to which network. Due to the increasing scarcity of IPv4 space, registrars and ISPs assign smaller and smaller netblocks to customers, leading to a more and more fragmented topology. Many older routers are limited to store 512k entries, and the Internet's routing table has become large enough to reach this limit. Tuesday morning, it appears to have exceeded this limit for a short time [2][3].

The large number of route announcements, and immediate removals shown in [2] could indicate a malicious intend behind this events (or a simple configuration error), but either way likely point to one entity "pushing" the size of the routing table beyond the 512k limit briefly. At around this time, one larger ISP (Windstream, AS7029) recovered from an unrelated outage and routing changes due to the recovery are one suspect that may have triggered the event.

Vendors published guidance for users of older routers how to avoid this issue [5]. This guidance has been available for a while. Please contact your vendor if you are affected. You may also want to consider upgrading your router. The routing table is likely going to get larger over the next few years until networks rely less on IPv4 and take advantage of IPv6.

 

[1] https://puck.nether.net/pipermail/outages/2014-August/007090.html
[2] http://www.cymru.com/BGP/prefix_delta.html (see the spike in deltas around that time)
[3] 
http://www.cidr-report.org/2.0/#General_Status  (note how close it is to 512k and rising)
[4] 
http://www.thewhir.com/web-hosting-news/liquidweb-among-companies-affected-major-outage-across-us-network-providers
[5] http://www.cisco.com/c/en/us/support/docs/switches/catalyst-6500-series-switches/117712-problemsolution-cat6500-00.html
 

Cheers,
Adrien de Beaupré
Intru-shun.ca Inc.
My SANS Teaching Schedule

Keywords:
2 comment(s)

Microsoft Patch Tuesday - August 2014

Published: 2014-08-12
Last Updated: 2014-08-13 02:07:14 UTC
by Alex Stanford (Version: 1)
8 comment(s)

Overview of the August 2014 Microsoft patches and their status.

# Affected Contra Indications - KB Known Exploits Microsoft rating(**) ISC rating(*)
clients servers
MS14-043 Vulnerability in Windows Media Center Could Allow Remote Code Execution
Microsoft Windows

CVE-2014-4060
KB 2978742 No Severity:Critical
Exploitability: 1
Critical Important
MS14-044 Vulnerabilities in SQL Server Could Allow Elevation of Privilege
Microsoft SQL Server

CVE-2014-1820
CVE-2014-4061
KB 2984340 No Severity:Important
Exploitability: 1
Important Important
MS14-045 Vulnerabilities in Kernel-Mode Drivers Could Allow Elevation Of Privilege
Microsoft Windows

CVE-2014-0318
CVE-2014-1819
CVE-2014-4064
KB 2984615 No Severity:Important
Exploitability: 1
Important Important
MS14-046 Vulnerability in .NET Framework Could Allow Security Feature Bypass
Microsoft Windows,Microsoft .NET Framework

CVE-2014-4062
KB 2984625 No Severity:Important
Exploitability: 1
Important Important
MS14-047 Vulnerability in LRPC Could Allow Security Feature Bypass
Microsoft Windows

CVE-2014-0316
KB 2978668 No Severity:Important
Exploitability: 1
Important Important
MS14-048 Vulnerability in OneNote Could Allow Remote Code Execution
Microsoft Office

CVE-2014-2815
KB 2977201 No Severity:Important
Exploitability: 1
Critical Important
MS14-049 Vulnerability in Windows Installer Service Could Allow Elevation of Privilege
Microsoft Windows

CVE-2014-1814
KB 2962490 No Severity:Important
Exploitability: 1
Important Important
MS14-050 Vulnerability in Microsoft SharePoint Server Could Allow Elevation of Privilege
Microsoft Server Software

CVE-2014-2816
KB 2977202 No Severity:Important
Exploitability: 1
Important Important
MS14-051 Cumulative Security Update for Internet Explorer
Microsoft Windows, Internet Explorer

CVE-2014-2774 CVE-2014-2784 CVE-2014-2796 CVE-2014-2808 CVE-2014-2810 CVE-2014-2811 CVE-2014-2817 CVE-2014-2818 CVE-2014-2819 CVE-2014-2820 CVE-2014-2821 CVE-2014-2822 CVE-2014-2823 CVE-2014-2824 CVE-2014-2825 CVE-2014-2826 CVE-2014-2827 CVE-2014-4050 CVE-2014-4051 CVE-2014-4052 CVE-2014-4055 CVE-2014-4056 CVE-2014-4057 CVE-2014-4058 CVE-2014-4063 CVE-2014-4067 CVE-2014-2774 CVE-2014-2784 CVE-2014-2796 CVE-2014-2808 CVE-2014-2810 CVE-2014-2811 CVE-2014-2817 CVE-2014-2818 CVE-2014-2819 CVE-2014-2820 CVE-2014-2821 CVE-2014-2822 CVE-2014-2823 CVE-2014-2824 CVE-2014-2825 CVE-2014-2826 CVE-2014-2827 CVE-2014-4050 CVE-2014-4051 CVE-2014-4052 CVE-2014-4055 CVE-2014-4056 CVE-2014-4057 CVE-2014-4058 CVE-2014-4063 CVE-2014-4067
KB 2976627 Yes! Severity:Critical
Exploitability: 1
Critical Important
We will update issues on this page for about a week or so as they evolve.
We appreciate updates
US based customers can call Microsoft for free patch related support on 1-866-PCSAFETY
(*): ISC rating
  • We use 4 levels:
    • PATCH NOW: Typically used where we see immediate danger of exploitation. Typical environments will want to deploy these patches ASAP. Workarounds are typically not accepted by users or are not possible. This rating is often used when typical deployments make it vulnerable and exploits are being used or easy to obtain or make.
    • Critical: Anything that needs little to become "interesting" for the dark side. Best approach is to test and deploy ASAP. Workarounds can give more time to test.
    • Important: Things where more testing and other measures can help.
    • Less Urgent practices for servers such as not using outlook, MSIE, word etc. to do traditional office or leisure work.
    • The rating is not a risk analysis as such. It is a rating of importance of the vulnerability and the perceived or even predicted threatatches.

--
Alex Stanford - GIAC GWEB & GIAC GSEC
Research Operations Manager,
SANS Internet Storm Center

Keywords: mspatchday
8 comment(s)

Adobe updates for 2014/08

Published: 2014-08-12
Last Updated: 2014-08-12 17:49:40 UTC
by Adrien de Beaupre (Version: 1)
0 comment(s)

Adobe has released security updates for Adobe Flash Player, Adobe AIR, Adobe Reader, and Acrobat. The updates are rated as critical and an impressive number of CVE entries.  CVE-2014-0538, CVE-2014-0540, CVE-2014-0541, CVE-2014-0542, CVE-2014-0543, CVE-2014-0544, CVE-2014-0545, CVE-2014-0546. Summary: update now. 

http://helpx.adobe.com/security/products/flash-player/apsb14-18.html
http://helpx.adobe.com/security/products/reader/apsb14-19.html

Cheers,
Adrien de Beaupré
Intru-shun.ca Inc.
My SANS Teaching Schedule

 

 

0 comment(s)

Host discovery with nmap

Published: 2014-08-12
Last Updated: 2014-08-12 12:27:30 UTC
by Adrien de Beaupre (Version: 1)
2 comment(s)

I enjoy performing penetration tests, I also enjoy teaching how to do penetration testing correctly. Next time up is SANS Sec560 network penetration testing in Albuquerque, NM. When I am teaching one of the points I make is to make good use of your tools. You really want to know which tools is appropriate for which parts of the engagement methodology and test plan. You also want to be familiar with the features and quirks of each tool in your kit. Most people are familiar with nmap as a port scanner, and often some of the other features such as service versioning and operating system fingerprinting. What I would like to talk about today are some of the features of nmap that work well together. One of the tasks in a penetration test or a vulnerability assessment is to identify which hosts are likely alive and responsive. Security testing involves sending stimulus, monitoring, and seeing responses. In this case we typically use nmap to send the stimulus, tcpdump to perform the monitoring, and the responses will tell us which hosts are responding to the packets nmap is sending.

Nmap is most often used to perform a ping sweep with its default series of packets. This option was -sP and is now -sn.

'nmap -sn -iL targets nmap-default-ping'

With root privileges this will send ICMP ech request (ping), a TCP SYN packet to port 443, a TCP ACK packet to port 80, and an ICMP timestamp request. This is efficient and in many cases is sufficient to identify those hosts that are responsive. In the case of a relatively flat internal network this is often the case.  

Tcpdump shows us that 4 packets were sent, 4 responses were also seen.

17:08:37.469613 IP 198.41.30.84 > 74.207.244.221: ICMP echo request, id 44412, seq 0, length 8
17:08:37.469641 IP 198.41.30.84.42601 > 74.207.244.221.443: Flags [S], seq 4035393928, win 1024, options [mss 1460], length 0
17:08:37.469658 IP 198.41.30.84.42601 > 74.207.244.221.80: Flags [.], ack 4035393928, win 1024, length 0
17:08:37.469664 IP 198.41.30.84 > 74.207.244.221: ICMP time stamp query id 30952 seq 0, length 20
17:08:37.541827 IP 74.207.244.221 > 198.41.30.84: ICMP echo reply, id 44412, seq 0, length 8
17:08:37.541841 IP 74.207.244.221.443 > 198.41.30.84.42601: Flags [R.], seq 0, ack 4035393929, win 0, length 0
17:08:37.541868 IP 74.207.244.221.80 > 198.41.30.84.42601: Flags [R], seq 4035393928, win 0, length 0
17:08:37.541968 IP 74.207.244.221 > 198.41.30.84: ICMP time stamp reply id 30952 seq 0: org 00:00:00.000, recv 21:00:18.026, xmit 21:00:18.026, length 20

(74.207.244.221 is scan.nmap.org)

The problem with only sending these 4 packets as the means to do hosts discovery is that it may miss many test cases, and is therefore less accurate. This is an issue in many pentests where we need to balance accuracy against efficient use of our time. Scanning an arbitrary /19 and we see the following results:

Nmap done: 8192 IP addresses (5668 hosts up) scanned in 24.31 seconds
           Raw packets sent: 26981 (968.952KB) | Rcvd: 5954 (176.168KB)

Now consider the following:
 'nmap -sn -PS -PA -PU -PY -PE -PP -PM -PO -n -vv --reason --packet-trace --traceroute -iL targets -oA nmap-full-sweep'
 
Nmap done: 8192 IP addresses (5676 hosts up) scanned in 438.24 seconds
           Raw packets sent: 80075 (2.518MB) | Rcvd: 94752 (4.014MB)

The --reason option tells us which stimulus the hosts responded to. --paket-trace outputs to the screen the packets flying back and forth, giving us a visual indicator to see if the tests are running correctly. The second scan sends 3 different ICMP packets, TCP, UDP, SCTP, and some raw IP packets. The only other tool I often run along with nmap is ike-scan to identify VPN devices that do not respond to any other packets. From the nmap man page:             
-sn: Ping Scan - disable port scan
-PS/PA/PU/PY[portlist]: TCP SYN/ACK, UDP or SCTP discovery to given ports
-PE/PP/PM: ICMP echo, timestamp, and netmask request discovery probes
-PO[protocol list]: IP Protocol Ping

We gained an additional 8 hosts identified as being responsive, however we sent over 3 times the packets and it took much much longer. The second scan is arguably much more accurate, and certainly is a much more impressive command line! Putting together the tools we can construct a nice bash script to run tcpdump and nmap against a target list. The script checks to see if has root privilege, sets up some variables, creats a scan log, runs tcpdump, runs nmap, then stops tcpdump.  

Cheers,
Adrien de Beaupre
Intru-shun.ca Inc.

Check out BSides Ottawa, our CfP is still open! Con is 5-6 September
http://www.bsidesottawa.ca/
I will be teaching SANS Sec560, Network Penetration Testing next in Albuquerque, NM!
http://www.sans.org/event/albuquerque-2014/course/network-penetration-testing-ethical-hacking

References:
http://nmap.org/book/man-host-discovery.html
http://www.nta-monitor.com/tools-resources/security-tools/ike-scan

Begin script:

#!/bin/bash
#Usage: discover.sh targetfilename
# Modified 10 August 2014, Adrien de Beaupre
# Check to see if we have root privileges, exit if not.
if [[ $EUID -ne 0 ]]; then
        echo "$0 must be run as root"
        exit 1
fi
# Check to see if we have a filename as one argument, exit if not.
# Number of arguments we want
GOODARGS=1
if [ $# -ne $GOODARGS ]; then
        echo "Usage: `basename $0` {targetfilename}"
        exit 1
fi
# Check to see if target file exists, exit if not
if [ ! -f $1 ]; then
        echo "Target file \"`basename $1`\" does not exist"
        exit 1
fi
# Declare variables
# Target file
TARGETS=`cat $1`
# Timestamp variable
NOW=$(date +%F-%s)
# Tcpdump program to run variable
TCPDUMP=/usr/local/sbin/tcpdump
# Run the tcpdump program
$TCPDUMP -n -v -i eth0 -w tcpdump-discovery.$NOW.$1.dump 2>/dev/null &
# Variable for the process ID
PID=$!
# Start discovery scan, create or append to scanlog
echo -e 'Discovery scan start:' $HOST | tee -a scanlog
date >> scanlog
# Nmap discovery
nmap -sn -PS -PA -PU -PY -PE -PP -PM -PO -n -vv --reason --packet-trace --traceroute -iL $1 -oA $1-discovery-nmap-$NOW
# Wait two seconds before killing sniffer
sleep 2
# Kill the tcpdump program by PID
echo -e 'Tcpdump stopped:' $HOST | tee -a scanlog
date >> scanlog
kill $PID

2 comment(s)
ISC StormCast for Tuesday, August 12th 2014 http://isc.sans.edu/podcastdetail.html?id=4101
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