Great article by Pete Freitag on Securing Apache Web Servers
(20 ways to Secure your Apache Configuration)

Here are 20 things you can do to make your apache configuration more secure.

Disclaimer: The thing about security is that there are no guarantees or absolutes. These suggestions should make your server a bit tighter, but don’t think your server is necessarily secure after following these suggestions.

Additionally some of these suggestions may decrease performance, or cause problems due to your environment. It is up to you to determine if any of the changes I suggest are not compatible with your requirements. In other words proceed at your own risk.

First, make sure you’ve installed latest security patches

There is no sense in putting locks on the windows, if your door is wide open. As such, if you’re not patched up there isn’t really much point in continuing any longer on this list.

Hide the Apache Version number, and other sensitive information.

By default many Apache installations tell the world what version of Apache you’re running, what operating system/version you’re running, and even what Apache Modules are installed on the server. Attackers can use this information to their advantage when performing an attack. It also sends the message that you have left most defaults alone.

There are two directives that you need to add, or edit in your httpd.conf file:

ServerSignature Off
ServerTokens Prod

The ServerSignature appears on the bottom of pages generated by apache such as 404 pages, directory listings, etc.

The ServerTokens directive is used to determine what Apache will put in the Server HTTP response header. By setting it to Prod it sets the HTTP response header as follows:

Server: Apache

If you’re super paranoid you could change this to something other than “Apache” by editing the source code, or by using mod_security (see below).

Make sure apache is running under its own user account and group

Several apache installations have it run as the user nobody. So suppose both Apache, and your mail server were running as nobody an attack through Apache may allow the mail server to also be compromised, and vise versa.

User apache
Group apache

Ensure that files outside the web root are not served

We don’t want apache to be able to access any files out side of its web root. So assuming all your web sites are placed under one directory (we will call this /web), you would set it up as follows:

<Directory />
  Order Deny,Allow
  Deny from all
  Options None
  AllowOverride None
</Directory>
<Directory /web>
  Order Allow,Deny
  Allow from all
</Directory>

Note that because we set Options None and AllowOverride None this will turn off all options and overrides for the server. You now have to add them explicitly for each directory that requires an Option or Override.

Turn off directory browsing

You can do this with an Options directive inside a Directory tag. Set Options to either None or -Indexes

Options -Indexes

Turn off server side includes

This is also done with the Options directive inside a Directory tag. Set Options to either None or -Includes

Options -Includes

Turn off CGI execution

If you’re not using CGI turn it off with the Options directive inside a Directory tag. Set Options to either None or -ExecCGI

Options -ExecCGI

Don’t allow apache to follow symbolic links

This can again can be done using the Options directive inside a Directory tag. Set Options to either None or -FollowSymLinks

Options -FollowSymLinks

Turning off multiple Options

If you want to turn off all Options simply use:

Options None

If you only want to turn off some separate each option with a space in your Options directive:

Options -ExecCGI -FollowSymLinks -Indexes

Turn off support for .htaccess files

This is done in a Directory tag but with the AllowOverride directive. Set it to None.

AllowOverride None

If you require Overrides ensure that they cannot be downloaded, and/or change the name to something other than .htaccess. For example we could change it to .httpdoverride, and block all files that start with .ht from being downloaded as follows:

AccessFileName .httpdoverride
<Files ~ "^\.ht">
    Order allow,deny
    Deny from all
    Satisfy All
</Files>

Run mod_security

mod_security is a super handy Apache module written by Ivan Ristic, the author of Apache Security from O’Reilly press.

You can do the following with mod_security:

• Simple filtering
• Regular Expression based filtering
• URL Encoding Validation
• Unicode Encoding Validation
• Auditing
• Null byte attack prevention
• Upload memory limits
• Server identity masking
• Built in Chroot support
• And more

Disable any unnecessary modules

Apache typically comes with several modules installed. Go through the apache module documentation and learn what each module you have enabled actually does. Many times you will find that you don’t need to have the said module enabled.

Look for lines in your httpd.conf that contain LoadModule. To disable the module you can typically just add a # at the beginning of the line. To search for modules run:

grep LoadModule httpd.conf

Here are some modules that are typically enabled but often not needed: mod_imap, mod_include, mod_info, mod_userdir, mod_status, mod_cgi, mod_autoindex.

Make sure only root has read access to apache’s config and binaries

This can be done assuming your apache installation is located at /usr/local/apache as follows:

chown -R root:root /usr/local/apache
chmod -R o-rwx /usr/local/apache

Lower the Timeout value

By default the Timeout directive is set to 300 seconds. You can decrease help mitigate the potential effects of a denial of service attack.

Timeout 45

Limiting large requests

Apache has several directives that allow you to limit the size of a request, this can also be useful for mitigating the effects of a denial of service attack.

A good place to start is the LimitRequestBody directive. This directive is set to unlimited by default. If you are allowing file uploads of no larger than 1MB, you could set this setting to something like:

LimitRequestBody 1048576

If you’re not allowing file uploads you can set it even smaller.

Some other directives to look at are LimitRequestFields, LimitRequestFieldSize and LimitRequestLine. These directives are set to a reasonable defaults for most servers, but you may want to tweak them to best fit your needs. See the documentation for more info.

Limiting the size of an XML Body

If you’re running mod_dav (typically used with subversion) then you may want to limit the max size of an XML request body. The LimitXMLRequestBody directive is only available on Apache 2, and its default value is 1 million bytes (approx 1mb). Many tutorials will have you set this value to 0 which means files of any size may be uploaded, which may be necessary if you’re using WebDAV to upload large files, but if you’re simply using it for source control, you can probably get away with setting an upper bound, such as 10mb:

LimitXMLRequestBody 10485760

Limiting Concurrency

Apache has several configuration settings that can be used to adjust handling of concurrent requests. The MaxClients is the maximum number of child processes that will be created to serve requests. This may be set too high if your server doesn’t have enough memory to handle a large number of concurrent requests.

Other directives such as MaxSpareServers, MaxRequestsPerChild, and on Apache2 ThreadsPerChild, ServerLimit, and MaxSpareThreads are important to adjust to match your operating system, and hardware.

Restricting Access by IP

If you have a resource that should only by accessed by a certain network, or IP address you can enforce this in your apache configuration. For instance if you want to restrict access to your intranet to allow only the 176.16 network:

Order Deny,Allow
Deny from all
Allow from 176.16.0.0/16

Or by IP:

Order Deny,Allow
Deny from all
Allow from 127.0.0.1

Adjusting KeepAlive settings

According to the Apache documentation using HTTP Keep Alive’s can improve client performance by as much as 50%, so be careful before changing these settings, you will be trading performance for a slight denial of service mitigation.

KeepAlive’s are turned on by default and you should leave them on, but you may consider changing the MaxKeepAliveRequests which defaults to 100, and the KeepAliveTimeout which defaults to 15. Analyze your log files to determine the appropriate values.

Run Apache in a Chroot environment

chroot allows you to run a program in its own isolated jail. This prevents a break in on one service from being able to effect anything else on the server.

It can be fairly tricky to set this up using chroot due to library dependencies. I mentioned above that the mod_security module has built in chroot support. It makes the process as simple as adding a mod_security directive to your configuration:

SecChrootDir /chroot/apache

There are however some caveats however, so check out the docs for more info.

Acknowledgments

I have found the book Apache Security to be a highly valuable resource for securing an apache web server. Some of the suggestions listed above were inspired by this book.

Few human made disasters in recent history have had a larger impact on the United States, North America, and in fact the western world than the attacks on the World Trade tower buildings. I encourage my friends and acquaintances to visit the 9/11 Tribute Movement website and pledge their memorial activity.

Remembrance of those who lost their lives and those who gave their lives in the line of duty is an important act that we all should honor.

 We will be doing our most difficult cross country mountain bike ride and will give a minute of silence at the top in honor of those who lost their lives as well as in support of the survivors.

Visit www.911day.org and tell the nation what you’ll be doing on 9/11/11.

Update: At 6,398′ on Moose Mountain, we gave a moment of silence.

You’ve just taken over as an information security director, manager, or architect at an organization. Either this is a new organization that has never had this role before or your predecessor has moved on for some reason. Now what? The following outlines steps that have been shown to be effective (also based on what’s been ineffective) getting traction and generating results within the first three months. Once some small successes are under your belt, you can grow the momentum to help the business grow faster or reduce the risk to their success (or both).

Now what do we do?

Apply a tried and true multi phase approach .. assess current state, determine desired target state, perform a gap analysis, implement improvements based on priority. Basically we need to establish current state, determine what future state should be, and use the gap analysis as the deliverables of the IT security program. There may be many trade-offs that are made due to limiters like political challenges, funding constraints and difficulty in changing corporate culture. The plan you build with the business gives you the ammunition needed to persuade all your stakeholders of the value in the changes you’ll be proposing.

1. Understand the Current Environment

For a manager or enterprise architect to determine where to start, a current state must be known. This is basically an inventory of what IT security controls, people and processes are in place. This inventory is used to determine what immediately known risks and gaps from relevant security control frameworks exist. The known risks and gaps gives us a starting point to understand where impacts on the business may originate from.

Take the opportunity to socialize foundational security concepts with your new business owners and solicit their input. What are the security related concerns they have? If there has been any articulation of Strengths, Weaknesses, Opportunities, and Threats (SWOT), obtaining that review can also give you an idea of weaknesses or threats that are indicative of missing controls. In the discussions with your new constituents, talk to the infrastructure managers and ask them what security related concerns keep them awake at night – there is likely some awareness but they don’t know how to move forward. Keep in mind most organizations will want a pragmatic approach versus an ivory tower perfect target state.

Some simple questions can quickly give you a picture of the state of security controls. For example, in organizations I’ve worked with, the network administrators could not provide me a complete “layer three” diagram – a diagram that shows all the network segments and how they hang together. It wasn’t that they didn’t want to, the diagrams simply didn’t exist. With over 1,500 network nodes over two data centers and two office complexes, the network group had the topology and configuration “in their heads”. Obvious weaknesses and threats include prevention of succession planning or disaster recovery, poor security transparency, and making nearly any change to the environment higher risk than necessary.

Another example is an organization that had weak asset control. At any point in time it was nearly impossible to determine if unauthorized network nodes existed, since the workstation, notebook, server, virtual machine, switches, firewalls, printers and any other network connected equipment were tracked separately, if at all. No regular audits were performed to reconcile what the organization had purchased was actually what was connected to their networks. This points to weak change control and weak asset control. Without strong asset control, it is difficult to offer assurance to the business owners that serious vulnerabilities have been mitigated to a level they can accept.

Ensure you’re asking questions that will allow you to develop future metrics, such as:

• Do security controls that are in place generate measurable performance statistics?
• How many user accounts are added, disabled, deleted per day/week/month/quarter?
• What volume of inbound email is spam/malware?
• Does the operations team have baselines of normal network, system, application activity?
• Profile of user accounts – how many are inactive (say 90 days)
• How automated is the new hire, dehire, change process? Is there room for manual error?
• How many administrator accounts are there (percentage of all accounts)
• What degree of individual user accountability is there? Are there signed acceptable use agreements?
• Are there accurate network topology and security zone as-built diagrams?
• Is there clear segregation of assets that contain high value data?
• Are content filtering and malware controls deployed?

All these identified issues can then be dropped into a mind map or even a spreadsheet to visualize the highest risks. More on this in a minute.

Read the rest of this entry »

For those odd times where you need to reset the password for a user on a Mac (OS X 10.5 Leopard) and you don't have access to the / an administrator account, this is a procedure that will work if you have physical access to the system and can reboot it. No boot DVD is needed if you can boot the system off the internal hard disk.

We boot into single user mode off the internal hard disk, then reset the target user password.

1. Boot into single user mode (press Command-S at power on)
2. Check the root filesystem first
   fsck -fy
3. Mount up the root filesystem
   mount -uw /
4. Load system directory services
   launchctl load /System/Library/LaunchDaemons/com.apple.DirectoryServices.plist
5. Edit user information
   dscl . -passwd /Users/username password (replace username with the targeted user and password with the new password)
6. Reboot then sign in with the new password.
   reboot

So I get a call this morning from a family member who is freaking out over a six hundred dollar iTunes invoice. Fortunately I knew this person didn't have an iTunes account (they use mine), so I knew right away it was a fraud. On inspecting the invoice, there were so few errors it's chilling. If this had of been an invoice from the (Acme Widget Company) that I do have an account with .. it's possible it may have worked. 

This is particularly evil, since it's associated with the Zeus trojan that steals banking credentials

The quality of phishing emails have dramatically improved as the quality assurance by malware miscreants improves. 

On closer inspection, there were three very subtle errors made on this iTunes phishing attack:

1. No street address was shown.  iTunes receipts always have your street address listed and spamming dirt bags don't have that (we hope).
2. Receipts (that I've paid attention to) come with an American style date format .. month / day / year.  Canadian or European formats are typically day / month / year or year / month / day.  This one is  day / month / year.
3. Modern corporate invoicing systems don't include leading zeros. Also the quantity and dollar amounts don't add up.

Every web hyper-link in this invoice except for the Apple Store Support and the Apple Legal links point to a non-Apple site.  All the links in iTunes invoices point to Apple.  In this case, the infected domain was  medicineni.com . This is particularly evil, since it's associated with the Zeus trojan that steals banking credentials. Bogus LinkedIn invites have also been confirmed to be coming from the Zeus botnet.

We still need to stay awake to the attacks by these malware miscreants, because they are getting better by the month.

This is a (non-comprehensive) list of the various security tools I have used. I started this list to keep track of tools that I've tried out and the level of satisfaction with them. Obviously there are hundreds of tools that any IT security professional uses throughout their career, so I'm just starting to put down the most recent, interesting or particularly effective. As I have time, I'll update and add comments/reviews/examples as well as break this into categories as the list grows.

Assessment / Attack Tools

Web Application Attack and Audit Framework (w3af)  w3af.sourceforge.net

IBM Rational AppScan  www-01.ibm.com/software/awdtools/appscan

Samurai Web Testing Framework samurai.inguardians.com

Visualization Tools

SecViz Security Visualization (davix) www.secviz.org/node/89

Password Tools

L0phtcrack  www.l0phtcrack.com

Forensics

V3RITY Oracle Database Forensics (www.v3rity.com/v3rity.php)  – "V3RITY is a tool that can be used in an Oracle forensics investigation of a suspected breach. It is the first of its kind and is currently in the beta stages of development."

Rapid7, which purchased the Metasploit attack framework last year, has agreed to sponsor the open source w3af web assessment and exploit project. This is fantastic news for web application development teams, since it shows the open source (and hence more affordable) tools they can use to improve the security of their applications are maturing.

Websites like sectools.org maintain lists of various security tools and point to numerous open source web application fuzzing and testing tools, including BurpSuite, Nikto, WebScarab, Whisker and Wikto. Although each of the open source tools I use have various strengths, w3af is IMHO the first reasonable challenger to commercial web application testing tools like IBM’s AppScan.

Can we please get rid of bad input validation errors now??

For a commercial IT security professional that wants to help an internal web application development team improve the security of their applications, tools like IBM’s AppScan and Acunetix WVS can save valuable time by generating reports that include not only the vulnerable URI but also include vulnerability background information (CVSS, OWASP, WASC), the specific HTTP request/response strings and suggested code fixes. This is particularly valuable to a security architect or operations role that is pressed for time (an army of one anyone?).

The w3af support from Rapid7 will enable this excellent tool to mature more quickly and improves the capability for any web development team, regardless of funding, to improve their security. Can we please get rid of bad input validation errors now?? My recent thesis illustrated the downright depressing numbers of SQL injection flaws that continue to exist. With tools like w3af, there is no excuse left for web developers to press applications into production with these injection flaws that are trivial to avoid. At the very least a survey of the NIST National Vulnerability Database does show the number of SQL injection flaws starting to drop. Unfortunately they still substantially outnumber traditional memory corruption flaws such as buffer overflows.

Explosion of SQL buffer errors

As you can see, the story up to 2008 was pretty grim for web applications – SQL injection flaws increased by over 1,500% in the same time buffer overflow errors increased by just over 500%.

Although it looks like there has been a reversal of the shocking explosion of SQL injection flaws, the sheer volume of these web application flaws is astonishing .. especially since injection flaws have been around for about 10 years. Not exactly a problem that has recently snuck up on us.

Web developers that still turn out applications that contain SQL or command injection errors and most cross site request forgery errors are simply guilty of gross negligence.

Despite the web development industry knowing these errors exist and good developers designing and coding to avoid these issues, there is still a need to build sufficient forensics around externally facing (publicly accessible) applications to enable reconstruction of attacks. In my next post, I outline a summary of my thesis “Effective SQL injection attack reconstruction using network recording”.

Resetting WordPress 3.0 user passwords can be done directly within MySQL through the following procedure.  This assumes your installation of WordPress stores user passwords in the wp_users table as MD5 hashes and the unique site prefix for all WordPress tables in MySQL is _x.

Connect to the database via your favorite GUI (phpMyAdmin, Navicat) or command line with either the WordPress role account or any other MySQL user account with select and update privileges on the WordPress database:

update wp_x_users set user_pass = MD5('123abc890') where user_login = 'administrator';

This will update the password for user ‘administrator’ to ’123abc890′.  Once this has completed, either flush the wp_x_users table or exit the tool used to access the database to cause the updates to be committed.  Sign into WordPress with the new password and optionally change the password via the user interface.

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.

Problem: VMware machines load boot loader immediately, no BIOS banner, so can’t get into BIOS to alter boot settings.
Solution: Edit the vm’s .vmx file and add the line:

bios.bootDelay = "5000"

which adds a 5000 millisecond (5 second) delay to the boot, or add:

bios.forceSetupOnce = "TRUE"

to make the VM enter the BIOS setup at the next boot.

Problem: VMware Fusion 3.0 doesn’t give a way to edit the virtual network settings via the GUI.
Solution: To change the subnet used by the NAT or HostOnly networks, go root in Mac OS X and edit

/Library/Application Support/VMware Fusion/networking

and set the following lines to the subnets desired:

answer VNET_1_HOSTONLY_SUBNET 192.168.35.0
answer VNET_8_HOSTONLY_SUBNET 10.10.1.0

To add additional custom isolated host only VLANs, also edit the networking file and add additional VNET definitions. There can apparently only be 8 VLANs with VLAN 1 and 8 already pre-defined.

answer VNET_2_DHCP no
answer VNET_2_HOSTONLY_NETMASK 255.255.255.0
answer VNET_2_HOSTONLY_SUBNET 10.10.21.0
answer VNET_2_VIRTUAL_ADAPTER yes
answer VNET_3_DHCP no
answer VNET_3_HOSTONLY_NETMASK 255.255.255.0
answer VNET_3_HOSTONLY_SUBNET 10.10.22.0
answer VNET_3_VIRTUAL_ADAPTER yes
answer VNET_4_DHCP no
answer VNET_4_HOSTONLY_NETMASK 255.255.255.0
answer VNET_4_HOSTONLY_SUBNET 10.10.23.0
answer VNET_4_VIRTUAL_ADAPTER yes

Now create your vm with as many network interfaces as you have separate VLANs (vnet) then edit the node.vmx vm configuration file and change the interfacename.connectionType to custom, and define the VLAN (vnet) that interface will attach to:

#ethernet0.connectionType = "nat"
ethernet0.connectionType = "custom"
ethernet0.vnet = "vmnet3"

Also realize that VMware will take the .1 host address on each vmnet – so you cannot assign .1 to any of your VMs.

Problem: Ubuntu 9.10 persistent network configuration (stores the MAC address of network adapters), so if you copy a machine, by default Ubuntu will setup a new logical adapter (eth1) since the MAC address has changed (when you answer I Copied It in VMware).
Solution: Tell VMware you copied the machine, so it will chose a unique MAC address. Boot Ubuntu into single user mode (another article on that to follow) then edit the MAC address associated with eth0.

sudo vi /etc/udev/rules.d/70-persistent-net.rules

find the stanza of the network interface in question (NAME=”eth0″) and set the following ATTR tag to the new MAC address:

ATTR{address}=="new-mac-address-here"