ASL WAF
Introduction
The ASL WAF has two non-exclusive modes operation:
1) Embedded mode
2) Proxy mode
Embedded mode
Embedded mode works with Apache 2.x. ASL will install a special module in Apache to give it native WAF protection capabilities. This installation will occur when ASL is installed.
Proxy mode
Proxy mode allows ASL to protect any HTTP and/or HTTPS service, either a local server (such as when using a web server that does not support embedded mode) or a remove server.
Configuration
The ASL WAF is initially configured during the install of ASL. If Apache is installed on the system, ASL will attempt to install the embedded WAF module. If Apache is installed on the system via package management, then this will occur automatically and you will not need to configure the WAF further to protect an installed Apache instance.
Once ASL is installed, if you need to do so, you can configure the WAF through three parts of the ASL GUI:
WAF Tab
This tab is used to setup the WAF. There are three types of WAF you can configure:
embedded
The embedded WAF is an apache module that is installed on any local Apache installations. This should be setup by default, if you are running apache on the system.
local
This type of WAF is used to protect any local HTTP and/or HTTPS services that may be running on the system itself, where the embedded WAF module can not be used. For example, if the system was running a tomcat or litespeed, which do not support the WAF embedded WAF module. You can configure a WAF to protect these services.
To setup a local WAF simply follow these steps:
Step 1) Log into the ASL GUI
Step 2) Click the WAF tab
Step 3) Select WAF Config
This will pull up the WAF Config window, which will show the existing WAFs.
Step 4) Click "Enable T-WAF". If you see "Disable T-WAF" this option has already been enabled.
Step 5) Click "Add"
This will will pull up the "Add WAF Config" window.
Step 6) Click on the "Add protection for" drop down. Select "local"
This will present you with two options:
Local Port: Type in the local port you wish to protect.
Note: Check if you have any embedded WAFs installed on the system before you do this. If you have an embedded WAF already installed on port 80, as should occur if you have Apache installed (and its package managed), then enabling the T-WAF in front of Apache would create a loop. Its not necessary to put a WAF in front of a service that is protected via embedded mode.
SSL: Select this if the service you wish to protect is SSL based.
If you select SSL, then you will see this additional options:
Path to SSL Certificate: Provide the filesystem path to the SSL certificate for this service.
Path to SSL Key file: Provide the filesystem path to the SSL key file for this service.
Step 7) Then click Save
remote
This type of WAF is used to protect any remote HTTP and/or HTTPS services that are not running on the system itself. For example, if you have a remote webserver you wish to protect, you can configure a WAF to protect these services. The remote WAF can support two proxy modes: domain based and IP based.
name based remote
Domain based or name nased WAFs allow you to use a single IP address on the WAF, and to direct WAF requests to different backend servers depending on their domain or full qualified domain name, or even to specific URL.
IP based remote
IP based WAFs allow you to redirect all traffic to an IP address on WAF to a specific destination host or URL.
Setting up a remote WAF
To setup a remote WAF simply follow these steps:
Step 1) Log into the ASL GUI
Step 2) Click the WAF tab
Step 3) Select WAF Config
This will pull up the WAF Config window, which will show the existing WAFs.
Step 4) Click "Enable T-WAF". If you see "Disable T-WAF" this option has already been enabled.
Step 5) Click "Add"
This will will pull up the "Add WAF Config" window.
Step 6) Click on the "Add protection for" drop down. Select "remote"
This will present you with a dropdown options to setup the WAF as either domain based or IP based.
Step 7) If you select name based you will be presented with these options:
Domain Name: Enter the domain name or full qualified domain you wish to use. For example, if you want the WAF to handle traffic for intranet.example.com enter that FQDN in this box.
Local Url: Enter the local URL, if any, that the WAF should expect from the client to direct this connection to the remote host. The default of / is usually correct if you are forwarding all traffic for an FQDN or domain. If you only want the WAF to pass on specific requests for specific URLs, enter them here.
Destination: Enter the full URL you want the WAF to use as the destination server. Make sure you have DNS or /etc/hosts entries for this, otherwise the WAF will not be able to find the destination. This should also not be the same thing as "Domain Name:". You can also use https:// URLs here.
Remote Port: Type in the remote port for the backend server the WAF will be sending requests to.
SSL: Select SSL if you wish to accept SSL connections to the WAF. If you select this you will be presented with these additional options:
Path to SSL Certificate: Provide the filesystem path to the SSL certificate for this service.
Path to SSL Key file: Provide the filesystem path to the SSL key file for this service.
Skip to step 8
Step 7) If you select IP based you will be presented with these options
IP Address: Enter the IP address you want the WAF to listen on (you can set multiple IPs by adding additional remote WAFs). For example, if you want the WAF to redirect all traffic on IP address 1.2.3.4 to internal.example.com, type in 1.2.3.4.
Local Url: Enter the local URL, if any, that the WAF should expect from the client to direct this connection to the remote host. The default of / is usually correct if you are forwarding all traffic for an FQDN or domain. If you only want the WAF to pass on specific requests for specific URLs, enter them here.
Destination: Enter the full URL you want the WAF to use as the destination server. Make sure you have DNS or /etc/hosts entries for this, otherwise the WAF will not be able to find the destination. This should also not be the same thing as "Domain Name:". You can also use https:// here.
Remote Port: Type in the remote port for the backend server the WAF will be sending requests to.
SSL: Select SSL if you wish to accept SSL connections to the WAF. If you select this you will be presented with these additional options:
Path to SSL Certificate: Provide the filesystem path to the SSL certificate for this service.
Path to SSL Key file: Provide the filesystem path to the SSL key file for this service.
Step 8) Then click Save
ASL Configuration Settings
The WAFs settings are contained under the Configuration tab. To Configure the WAF follow this process:
Step 1) Log into the ASL GUI
Step 2) Click on the Configuration Tab
Step 3) Select the "ASL Configuration" sub menu
Step 4) Scroll down to the Mod_security configuration section. The following options are available:
MODSEC_ENABLED
Enable/Disable the entire WAF system
WAF_ENGINE
Set the WAF engine mode, there are three modes:
On - this tells the WAF to detect and block attacks.
DetectOnly - this tells the WAF to only detect and report attacks, but not to block them.
Off - Disables the WAF.
WAF_ENABLED
Enable/Disable Tortix WAF proxy. The tortix waf module, this module can process local or remote services through the Tortix Web Application Firewall (T-WAF) . (Default: Off)
WAF_CHROOTDIR
Configures the directory path that will be used to jail the web server process. (For the embedded WAF modules only). This lets you put the local apache instance into a chroot jail.
WAF_READSTATELIMIT
Sets the limit of the number of connections that can be in the Read state for the WAF. This helps to prevent DOS attacks. The default is generally good for most sites.
WAF_SECREQUESTBODYNOFILESLIMIT
(Default: 1048576) Configures the maximum request body size the WAF modules will accept for buffering. There is a hard limit of 1GB. This is not a limit on file sizes sent through the WAF, just request body sizes.
WAF_SECREQUESTBODYINMEMORYLIMIT
(Default: 131072) Configures the maximum request body size the WAF modules will store in memory. The is a hard limit of 1GB. The default is generally sufficient for any site.
WAF_DEFAULT_ACTION
Configures the block policy, deny the request or redirect the client to a landing page.
WAF_REDIRECT_URL
Used for WAF_DEFAULT_ACTION of "redirect". This is the URL to redirect blocked pages.
MODSEC_SERVERSIG
Field returned when a remote host queries what kind of web server this is. This can be used to hide what kind of server is running on the system, or what the WAFs are protecting.
MODSEC_UPLOADDIR
Configures the directory where intercepted files will be stored. If the WAF is configured to scan uploads, and this is set to On, then any malicious files the WAF detects will be stored in this directory on the server.
MODSEC_KEEPFILES
Configures whether or not the intercepted files will be kept after transaction is processed. It is recommended you set to this off.
MODSEC_LOGTYPE
Configures the type of audit logging mechanism to be used. Concurrent - audit log entries will be stored in separate files, one for each transaction. Serial - all audit log entries will be stored in the main audit logging file. The default is Concurrent, which is both faster and more reliable and works with ASL Gui. Serial logging is for legacy purposes and should not be enabled.
MODSEC_LOGFILE
The name of the log file that is used to store audit record headers. Do not change this unless you know what you are doing. It is generally not necessary to change this setting.
MODSEC_LOGELEMENT
Defines which part of each transaction are going to be recorded in audit log. Do not change the defaults unless you know what you are doing, this may break the GUI and active response systems.
Available audit log parts:
A: Audit log header (mandatory).
B: Request headers.
C: Request body (present only if the request body exists and ModSecurity is configured to intercept it).
D: Reserved for intermediary response headers; not implemented yet.
E: Intermediary response body (present only if ModSecurity is configured to intercept response bodies, and if the audit log engine is configured to record it). Intermediary response body is the same as the actual response body unless ModSecurity intercepts the intermediary response body, in which case the actual response body will contain the error message (either the Apache default error message, or the ErrorDocument page).
F: Final response headers (excluding the Date and Server headers, which are always added by Apache in the late stage of content delivery).
G: Reserved for the actual response body; not implemented yet.
H: Audit log trailer.
I: This part is a replacement for part C. It will log the same data as C in all cases except when multipart/form-data encoding in used. In this case, it will log a fake application/x-www-form-urlencoded body that contains the information about parameters but not about the files. This is handy if you don’t want to have (often large) files stored in your audit logs.
J: This part contains information about the files uploaded using multipart/form-data encoding.
K: This part contains a full list of every rule that matched (one per line) in the order they were matched. The rules are fully qualified and will thus show inherited actions and default operators.
Z: Final boundary, signifies the end of the entry (mandatory).
MODSEC_REQMEMLIMIT
Configures the maximum request body size ModSecurity will store in memory. The default are adequate for most sites, you should not change this unless you know what you are doing.
MODSEC_DEBUGLOG
Enable/Disable the ModSecurity debug log file. The debug log is located in /var/log/httpd/modsec_debug.log Enabling this will incur a substantial performance penalty on the system. You should not enable this on a production system, and only if you are debugging modsecurity rules.
Most users will want to leave this disabled.
MODSEC_CLEAN_ALERT
Number of days to retain mod_security alert data. The WAF will store the actual full requests of any intercepted attacks, to make it possible for you to investigate them and to report these to us, either for further investigation, false positives or for other forensics needs. The default is to keep these for 30 days.
MODSEC_DATADIR
Path where persistent data (e.g. IP address data, session data, etc) is to be stored.
MODSEC_AUDITDIR
Defines the path to the audit log files. Used only when Concurrent mode is configured.
MODSEC_TMPDIR
Configures the directory where temporary files will be created.
MODSEC_RESPONSEBODYLIMIT
Configures the maximum response body size that will be accepted for buffering.
MODSEC_RESPONSEBODYLIMITACTION
Controls what happens once a response body limit, configured with SecResponseBodyLimit, is encountered. There are two options:
ProcessPartial: Scan the response up to the limit and stop scanning when the limit is reached, but send the rest of the response.
Reject: If the response is greater than the Limit, reject the response entirely.
MODSEC_REQUESTBODYLIMIT
Ruleset Settings
These allow you to enable/disable entire Rulesets and classes of rules. If you want to configure a specific rule, use the Rule Manager.
MODSEC_00_WHITELIST
Enable/Disable whitelist rule class. Note enabling this will bypass *ALL* security checks for hosts on the whitelist. It is a truly terrifying option. Enabling this will void your support, just kidding. But seriously, enabling this will in fact tell the WAF to totally ignore everything from the source, it wont even alert. We dont recommend you you use this.
===== MODSEC_00_ANTIEVASION
Enable/Disable the antievasion rule class. This ruleset prevents attacks that try to bypass the WAF itself.
MODSEC_00_STRICT
Enable/Disable the strict multiform checks rule class. This ruleset enforces strict adherence RFCs for multiform messages. This prevents advanced attacks that may try to bypass the WAF. Note: Broken applications and clients that do not adhere to RFCs will not be able to send multiform to the system if you enable this. This not a false positive, these clients and applications are broken. If you are unfortunately stuck with these, you will have to disable this.
MODSEC_00_RBL
Enable/Disable Real-time Black List (RBL) rule class. You should only use this if the ASL server has a really fast local DNS server. This ruleset will look up every request in the DNS to see if its on a blacklist, and will not finish serving the request until the DNS server responds. This can slow down requests if the DNS server is slow. Basically, web requests will move at the speed of the DNS servers replies.
MODSEC_00_AE_RULES
Enable/Disable the antievasion rule class. This ruleset prevents attacks that try to bypass the WAF itself.
MODSEC_01_RULES
Enable/Disable the Bypass protection rule class. This ruleset prevents attacks that try to bypass the WAF itself or can be used to trick applications into parsing data in ways that may compromise the application.
MODSEC_10_ANTIMALWARE
Enable/Disable the anti-malware rule class. This will look at any requests to the system for known malware domains and indicators of malware injection requests (this does not do the same thing as the MODSEC_99_SCANNER class, which will inspect uploads for malware).
MODSEC_10_RULES
Enable/Disable the core rule class. This class contains the core generic rules, which will look for things like SQLi, XSS, CSRF, recursion, code injection, command injection, XML attacks and other generic attack patterns. You should always leave this class enabled.
MODSEC_11_ADV_RULES
Enable/Disable the advanced protection rule class. This class contains advanced rules.
MODSEC_11_DLP
Enable/Disable the data loss protection rule class. This will detect certain Data Loss events, such as credit card information being sent or errors messages from applications that may reveal sensitive information or that the system or application is vulnerable to particular attack.
MODSEC_12_BRUTE
Enable/Disable the brute force attack protection rule class. Detects attempts to brute force web applications authentication mechanisms.
MODSEC_20_USERAGENTS
Enable/Disable the useragents rule class. Detects known malicious or suspicious user agents.
MODSEC_30_ANTISPAM
Enable/Disable the anti-spam rule class. This class contains tuned antispam rules, designed to work with all known blogs, forums, guestbooks, CMS' and other web content management systems that allow users to post content.
MODSEC_31_ANTISPAM_URI
Enable/Disable the anti-spam URI rule class. Looks up all URIs in a post against RBLs to see if its a known spam domain. As with the MODSEC_00_RBL rules, these should only be used if the server has a local fast DNS server. This ruleset will look up every request in the DNS to see if its on a blacklist, and will not finish serving the request until the DNS server responds. This can slow down requests if the DNS server is slow. Basically, web requests will move at the speed of the DNS servers replies.
MODSEC_50_ROOTKITS
Enable/Disable the rootkit rule class. This class detects and blocks known rootkits, PHP/ASP/PERL shells, spam tools and other malicious web applications from running on the system. (These rules exist for cases where malicious software may already be installed on the system, this is a defense in depth rule set)
MODSEC_60_RECONS
Enable/Disable the recon rule class. This class blocks known "google hacks" or webserver probes that look for vulnerable applications and signs of compromised systems running unauthorized shells, or unprotected applications that allow uploads which would give an attacker access to the system.
MODSEC_61_DLP
Enable/Disable the data loss protection class. These rules detect Data Loss Search engine "hacks". These are search engine probes for sensitive files, often used by malicious parties to find sensitive information accidentally exposed on web servers.
MODSEC_99_JITP
Enable/Disable the Just In Time Patches(JITP) rule class. Just in Time Patches. We publish JITPs daily if there is a new web application vulnerability that the 10_asl_rules.conf do not protect the system against. These are tuned rules for specific vulnerabilities in a web application.
MODSEC_99_REDACTOR
Enable/Disable the automatic malicious/hidden iframe and malware removal rule class. Automatically removes malicious code from web pages, such as hidden iframes, encoded javascript and other malicious code.
MODSEC_99_MALWARE_OUTPUT
Enable/Disable the malware output rule class.
MODSEC_99_SCANNER
Enable/Disable PHP check enforcement mode. Note setting this to no will still test for vulnerabilitites.
Rule Manager
The Rule manager can be used to configure individual WAF rules, such as what response the system such take for that rule, if an email or GUI alert should be presented, and so on. The following are the options you can use for each rule:
