Allen Pomeroy

Blog of an IT security specialist .: beta :.

How to secure your home PC

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Whether you have a Mac or a Windows PC, there are some basic steps you can take to reduce the risk and personal impact of a malware infection.  This advise is especially impactful when you have just purchased a new Mac or Windows system. There are several steps that you can take to protect your new investment and more importantly your information. In the following detail, I mainly focus on Windows as that’s the main technology that my non-IT type friends ask about.

Basically what you should be doing is:

  1. Ensure that a hardware firewall/router is in between the internet and the PC (I’ll just call it a firewall from now on)
    • Use a recognized brand name like Linksys, avoid the no-name generics as they often have bad defaults and don’t implement the stateful-packet-inspection that you want to filter out most of the cruft on the Internet from reaching your PC
  2. Ensure all default passwords on the firewall and PC have been changed
    • When you initially turn on the power to your PC and to your firewall, do NOT have them connected to your cable or DSL modem initially.  Do the setup of your firewall and PC first in order to ensure malware doesn’t have a chance to get at your shiny new PC before you’ve turned on the needed protection
    • Point a browser to your firewall (likely 192.168.0.1 or 192.168.1.1) and change the default administrator password.  This is very important, as some malware will seek out your firewall and try to use the manufacturer default password to change things like your DNS server settings – inserting the bad guys in between you and the rest of the Internet (eg. forcing your traffic to them first before it goes to your bank)
  3. All normal accounts used for day-to-day business on the computer should NOT have administrator privilege (see my post on running without admin privileges)
    • On Windows XP, Vista (and I think 7), the default “user” that accesses the PC has full administrative privilege, that enables software  installation and configuration changes.  This is very dangerous, as malware that you come in contact with from infected emails or websites use this privilege to install their spyware, keyloggers, backdoors and other nasty stuff on your PC – without your explicit permission
    • Set a password for your Administrator account
    • Create a new user right away, before you setup your email, music, photos, documents, etc; ensure that new user is NOT a Computer Administrator
    • Always login with this non-Administrator username for your day-to-day use; only use the Computer Administrator username for software installation and configuration changes.
  4. Never surf the Internet with an account that has administrative privilege
  5. If this is a common PC for a business, ensure employees accounts are individually assigned (if practical). Ensure those employee accounts are not administrators (unless there is a need and a high degree of trust)
  6. Run a good commercial anti-virus program with annual software support (or a subscription)
    • There are some good free AV packages (AVG, Clamwin, Avast) .. Google them for the links
    • Sophos makes a good Mac AV package .. yes, Macs are vulnerable to malware as well; it’s just not as prevalent
  7. Finally ensure regular (daily) backups are being run to protect your business, financial, customer information from loss if there is a problem with the PC
  8. For setup of your wireless access point (if you have one .. sometimes it’s built into the router/firewall)
    • Chose wireless encryption of at least WPA or WPA2 .. never use WEP or no encryption
    • There is no significant increase in security by obscuring your network name (SSID)
    • Don’t use any personally identifiable information in your network name

If you are unsure of how to do any of these steps, get one of your computer knowledgeable friends to help you.  Of course if you are purchasing a new system right now, I’d strongly recommend you check out Apple’s Mac products.  They’re not immune to malware, but the architecture and core are by design much less vulnerable to the types of malware that plague Windows.

  • Author: edhacker
  • Published: Sep 8th, 2009
  • Category: tech
  • Comments: 1

Sifting through Checkpoint FW1 logs

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Recently I found myself in the unhappy position of needing to sift through slightly more than a billion Checkpoint Firewall-1 log lines, looking for specific patterns of access. The problem was that many of the exported fwm log files had differing column positions and there had been many ruleset changes over the course of 11 months worth of log data. Many of the excellent FW1 log summarization tools (such as Peter Sundstrom’s fwlogsum) didn’t handle the hundreds of files and differing column positions.

The final scripted solution was processing over 11,000 lines/second .. and still took over 23 hours for the first run.

Log file exports via fwm logexport can have variable column positioning, except for record ID number “num”, which is *always* column number one.  I see three viable alternatives to the changing column position in the ASCII log files exported via fwm – so we can automate the log processing:

  • Export the FW1 log file to ASCII via
    fwm logexport -i fw1-binary-logfile -o fw1-ascii-logfile.txt -n -p
    1. Parse the header line (line #1) of every log file and dynamically map (rearrange) the columns to a pre-determined standard in memory before further processing (painful, expensive)
    2. Tell Checkpoint fwm to export in a fixed column ordering
        create
        logexport.ini
        and place in
        $FWDIR/conf directory
        eg. fwmgmtsrv:
        C:\WINDOWS\FW1\R65\FW1\conf
        logexport.ini:
        [Fields_Info]
        included_fields = num,date,time,orig,origin_id,type,action,alert,i/f_name,
        i/f_dir,product,rule,src,dst,proto,service,s_port,xlatesrc,xlatedst,
        nat_rulenum,nat_addtnl_rulenum,xlatesport,xlatedport,user,
        partner,community,session_id,ipv6_src,ipv6_dst,
        srckeyid,dstkeyid,CookieI,CookieR,msgid,elapsed,
        bytes,packets,start_time,snid,ua_snid,d_name,id_src,ua_operation,
        sso_type_desc,app_name,auth_domain,uname4domain,wa_headers,
        result_desc,r_dest,comment,url,redirect_url,enc_desc,e2e_enc_desc,
        auth_result,attack,log_sys_message,
        rule_uid,rule_name,service_id,resource,reason,cat_server,
        dstname,SOAP Method,category,ICMP,message_info,
        TCP flags,rpc_prog,Total logs,
        Suppressed logs,DCE-RPC Interface UUID,Packet info,
        message,ip_id,ip_len,ip_offset,fragments_dropped,during_sec
    3. Use OPSEC LEA tools to extract event log records instead of export via fwm logexport

    Once the ASCII log files are available for processing, my fw1logsearch.pl script can be used to find complex patterns of interest.  Any matching records found by fw1logsearch will be output with an initial FW1 header line so that fw1logsearch can be used iteratively, to build very complex search criteria.  fw1logsearch can also write out a discard file allowing completely negative logic searches resulting in 100% of the input data separated into a match file and a didn’t match file.  Some examples of how I’ve used it are shown here:

    gunzip -c fwlogs/2009*gz | \
    fw1logsearch.pl --allinclude \
    -S '10\.1\.1[1359]\.|10\.2\.1[01]\.|192\.168\.2[245]\.' \
    -d '10\.1\.1[1359]\.|10\.2\.1[01]\.|192\.168\.2[245]\.' \
    -p '^1310$|^1411$|^1812$|^455' | \
    fw1logsearch.pl -S '192\.168\.22\.14$|10\.2\.11\.12$' |\
    fw1logsearch.pl --allexclude \
    -S '^192\.168\.24\.12$' -P '^1310$' --rejectfile 192-168-24-12-port-1310.txt

    Line by line:
    1. Unzip the compressed ASCII log files, feed them to the first instance of fw1logsearch.pl
    2. First fw1logsearch – all conditions must be true for any events to match
    Source address must NOT be in any of the following regex ranges:
    10.1.11.* 10.1.13.* 10.1.15.* 10.1.19.*
    10.2.10.* 10.2.11.*
    192.168.22.* 192.168.24.* 192.168.25.*
    Destination address must be in one of the same following regex ranges.
    Service (destination port) must be one of:
    Exactly port: 1310, 1411, 1812, or any port starting with 455
    No protocol is specified, so it will match either TCP or UDP

    fw1logsearch.pl will output any matching events to stdout, including a FW1 log header line, so the next instance of fw1logsearch.pl continues filtering the result set.

    3. The second fw1logsearch.pl specifies Source Address must not be any of the following
    192.168.22.14

    10.2.11.12

    4. The last fw1logsearch.pl excludes port 1310 from 192.168.24.12, and puts all those records into a separate reject file, while writing the other records to stdout.

    This script has been used to process over 4 billion records within the project I wrote it for – and precisely found all the use of particular business cases I needed to modify.  The result was zero outages and no unintended business interruption.

    Basic syntax/help file:

    Usage:  fw1logsearch.pl
    [-a|--incaction|-A|--excaction <action regex>]
    [-p|--incservice|-P|--excservice <dst port regex>]
    [-b|--incs_port|-B|--excs_port <src port regex>]
    [-s|--incsrc|-S|--excsrc <src regex>]
    [-d|--incdst|-D|--excdst <dst regex>]
    [-o|--incorig|-O|--excorig <fw regex>]
    [-r|--incrule|-R|--excrule <rule-number regex>]
    [-t|--incproto|-T|--excproto <proto regex>]

    [--dnscache <dns-cache-file>]
    [--resolveip]
    [--allinclude]
    [--allexclude]
    [--rejectfile <file>]
    [--debug <level>]

    fw1logsearch.pl will search a fwm logexport text file for regex patterns specified for supported columns (such as service, src, dst, rule, action, proto and orig).

    Include and exclude regex matches may be specified on the same line, although they both will include (print) a line or exclude (reject) a line based on single matches.  Allinclude or Allexclude must be specified to force a match
    only on all specified column regex patterns.

    Regex patterns can be enclosed with single quotes to include characters that are special to the shell, such as the ‘or’ (|) operator.

    Header will be output only if there are any matching lines.

    Example invocations:
    $ cat 2008-07-07*txt | \
    fw1logsearch.pl \
    -p ‘53|domain’ \
    -d ‘192.168.1.2|host1|10.10.1.2|host2′ \
    -o ‘192.168.2.3|10.10.2.4|10.10.4.5′ \
    -S ‘64.65.66.67|32.33.34.35|10.10.*|192.168.*’ \
    –resolveip
    Will require destination port (service) to be 53, destination IP to be any of 192.168.1.2, host1, 10.10.1.2, or host2  the reporting firewall (origin) to be any of 192.168.2.3, 10.10.2.4, or 10.10.4.5  and the source IP must not be
    any of 64.65.66.67, 32.33.34.35, 10.10.*, or 192.168.*  Any lines that match this criteria, will display and the orig, src, and dst columns will use the default DNS cache file (dynamically built/managed) to perform name resolution, replacing the IP addresses where possible.

    Include regex patterns:
    -a  –incaction    Rule action (accept, deny)
    -b  –incs_port    Source port (s_port)
    -p  –incservice   Destination port (service)
    -s  –incsrc       Source IP|hostname
    -d  –incdst       Destination IP|hostname
    -o  –incorig      Reporting FW IP|hostname
    -r  –incrule      Rule number that triggered entry
    -t  –incproto     Protocol of connection

    Exclude regex patterns:
    -A  –excaction    Rule action (accept, deny)
    -B  –excs_port    Source port (s_port)
    -P  –excservice   Destination port (service)
    -S  –excsrc       Source IP|hostname
    -D  –excdst       Destination IP|hostname
    -O  –excorig      Reporting FW IP|hostname
    -R  –excrule      Rule number that triggered entry
    -T  –excproto     Protocol of connection

    Other options:
    –debug {level} Turn on debugging
    –dnscache      Specify location of DNS cache file to be used with
    the Resolve IPs option
    –resolveip     Resolve IPs for orig, src, and dst columns AFTER filtering
    –rejectfile    Write out all rejected lines to a specified file

    Download fw1logsearch.pl

    High availability firewalls with OpenBSD, pf and CARP

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    One can now inexpensively build a fault tolerant firewall cluster that removes any single point of failure in the security policy enforcement points at your security zone boundaries. Synchronous firewall state table updates and an open source version of virtual router redundancy protocol (CARP) gives the ability to seamlessly insert or remove firewalls from a cluster. No more patching firewalls at 2am hoping for the best (or not patching because it’s too hard).

    PDF

    Soekris net5501 SBC Linux installation

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    Soekris Engineering net5501 SBC setup with Linux

    2008/09/03

    net5501 is a x86 SBC that I ordered with 4 10/100 ethernet ports, 512MB memory, 500MHz Geode LX CPU

    Serial console is used for setup of net5501 – BIOS writes to serial port since there is no xVGA port. <ctrl-p> to enter BIOS setup. DB9 pinout:

    2 — 3

    3 — 2

    5 — 5

    Use 19,200 bps 8 data bits, no parity, 1 stop

    With the Macbook Pro, I use a Keyspan USA-19HS USB <–> DB9 RS232 serial converter (and DB9-RJ45 adapters to implement the null modem configuration and allow me to use an ethernet cable for the serial console <–> Keyspan device.

    On OS X (10.5) I use “screen” to provide the serial terminal interface:

    $ screen /dev/tty.USA19H1a2P1.1 19200,8

    <ctrl-a><ctrl-\> to exit

    On the net5501 BIOS, PXEBoot is disabled:

    set PXEBoot=Disabled

    I setup voyage-0.5.0 on a compact flash card then installed the card into the net5501 – works great the first boot

    Default root info: root / voyage

    OpenBSD setup info:

    http://techblagh.blogspot.com/2008/08/installing-openbsd-43-on-soekris-5501.html

    Linux iptables notes

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    Add local redirection of low port to unpriv high port

    Remove any existing entries:

    iptables -t nat -D PREROUTING –src 0/0 -p tcp –dport 25 -j REDIRECT –to-ports 11025 2> /dev/null
    iptables -t nat -D PREROUTING –src 0/0 -p tcp –dport 80 -j REDIRECT –to-ports 8080 2> /dev/null

    Add new redirects:
    iptables -t nat -I PREROUTING –src 0/0 -p tcp –dport 25 -j REDIRECT –to-ports 11025
    iptables -t nat -I PREROUTING –src 0/0 -p tcp –dport 80 -j REDIRECT –to-ports 8080

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