John, a professional hacker, decided to use DNS to perform data exfiltration on a target network, in this process, he embedded malicious data into the DNS protocol packets that even DNSSEC cannot detect. Using this technique. John successfully injected malware to bypass a firewall and maintained communication with the victim machine and C&C server. What is the technique employed by John to bypass the firewall?
Correct Answer: C
DNS tunneling may be a method wont to send data over the DNS protocol, a protocol which has never been intended for data transfer. due to that, people tend to overlook it and it's become a well-liked but effective tool in many attacks. Most popular use case for DNS tunneling is obtaining free internet through bypassing captive portals at airports, hotels, or if you are feeling patient the not-so-cheap on the wing Wi-Fi. On those shared internet hotspots HTTP traffic is blocked until a username/password is provided, however DNS traffic is usually still allowed within the background: we will encode our HTTP traffic over DNS and voilà, we've internet access. This sounds fun but reality is, browsing anything on DNS tunneling is slow. Like, back to 1998 slow. Another more dangerous use of DNS tunneling would be bypassing network security devices (Firewalls, DLP appliances...) to line up an immediate and unmonitored communications channel on an organisation's network. Possibilities here are endless: Data exfiltration, fixing another penetration testing tool... you name it. To make it even more worrying, there's an outsized amount of easy to use DNS tunneling tools out there. There's even a minimum of one VPN over DNS protocol provider (warning: the planning of the web site is hideous, making me doubt on the legitimacy of it). As a pentester all this is often great, as a network admin not such a lot . How does it work: For those that ignoramus about DNS protocol but still made it here, i feel you deserve a really brief on what DNS does: DNS is sort of a phonebook for the web , it translates URLs (human-friendly language, the person's name), into an IP address (machine-friendly language, the phone number). That helps us remember many websites, same as we will remember many people's names. For those that know what DNS is i might suggest looking here for a fast refresh on DNS protocol, but briefly what you would like to understand is: * A Record: Maps a website name to an IP address. example.com ? 12.34.52.67 * NS Record (a.k.a. Nameserver record): Maps a website name to an inventory of DNS servers, just in case our website is hosted in multiple servers. example.com ? server1.example.com, server2.example.com Who is involved in DNS tunneling? * Client. Will launch DNS requests with data in them to a website . * One Domain that we will configure. So DNS servers will redirect its requests to an outlined server of our own. * Server. this is often the defined nameserver which can ultimately receive the DNS requests. The 6 Steps in DNS tunneling (simplified): 1. The client encodes data during a DNS request. The way it does this is often by prepending a bit of knowledge within the domain of the request. for instance : mypieceofdata.server1.example.com 2. The DNS request goes bent a DNS server. 3. The DNS server finds out the A register of your domain with the IP address of your server. 4. The request for mypieceofdata.server1.example.com is forwarded to the server. 5. The server processes regardless of the mypieceofdata was alleged to do. Let's assume it had been an HTTP request. 6. The server replies back over DNS and woop woop, we've got signal. Bypassing Firewalls through the DNS Tunneling Method DNS operates using UDP, and it has a 255-byte limit on outbound queries. Moreover, it allows only alphanumeric characters and hyphens. Such small size constraints on external queries allow DNS to be used as an ideal choice to perform data exfiltration by various malicious entities. Since corrupt or malicious data can be secretly embedded into the DNS protocol packets, even DNSSEC cannot detect the abnormality in DNS tunneling. It is effectively used by malware to bypass the firewall to maintain communication between the victim machine and the C&C server. Tools such as NSTX (https://sourceforge.net), Heyoka (http://heyoka.sourceforge.netuse), and Iodine (https://code.kryo.se) use this technique of tunneling traffic across DNS port 53. CEH v11 Module 12 Page 994
Question 247
You are logged in as a local admin on a Windows 7 system and you need to launch the Computer Management Console from command line. Which command would you use?
Correct Answer: A
To start the Computer Management Console from command line just type compmgmt.msc /computer:computername in your run box or at the command line and it should automatically open the Computer Management console. References: http://www.waynezim.com/tag/compmgmtmsc/
Question 248
Which of the following antennas is commonly used in communications for a frequency band of 10 MHz to VHF and UHF?
Correct Answer: B
Question 249
Let's imagine three companies (A, B and C), all competing in a challenging global environment. Company A and B are working together in developing a product that will generate a major competitive advantage for them. Company A has a secure DNS server while company B has a DNS server vulnerable to spoofing. With a spoofing attack on the DNS server of company B, company C gains access to outgoing e-mails from company B. How do you prevent DNS spoofing?
Correct Answer: C
Question 250
You're the security manager for a tech company that uses a database to store sensitive customer data. You have implemented countermeasures against SQL injection attacks. Recently, you noticed some suspicious activities and suspect an attacker is using SQL injection techniques. The attacker is believed to use different forms of payloads in his SQL queries. In the case of a successful SQL injection attack, which of the following payloads would have the most significant impact?
Correct Answer: C
The payload that would have the most significant impact in the case of a successful SQL injection attack is OR 'a'='a; DROP TABLE members; --. This payload combines the manipulation of the WHERE clause with a destructive action, causing data loss. This payload works as follows: * The OR 'a'='a part of the payload is a logical expression that is always true, regardless of the input or the condition of the SQL statement. This part of the payload allows the attacker to bypass any authentication or authorization checks that may be implemented in the SQL statement, such as a login form or a search query. * The ; part of the payload is a statement terminator that marks the end of the current SQL statement and allows the attacker to inject another SQL statement after it. This part of the payload enables the attacker to execute multiple SQL statements in a single query, which is also known as stacked queries or batched queries. * The DROP TABLE members part of the payload is a destructive SQL statement that deletes the entire table named members from the database. This part of the payload causes data loss and may compromise the functionality and integrity of the application that relies on the table. The table name may vary depending on the target database, but the attacker can use other techniques, such as error-based or union-based SQL injection, to discover the table names before executing the drop statement. * The - part of the payload is a comment symbol that tells the SQL engine to ignore the rest of the query. This part of the payload helps the attacker to avoid any syntax errors or unwanted results that may arise from the original query. The other options are not as impactful as option C for the following reasons: * A. 'OR 'T="1: This payload manipulates the WHERE clause of an SQL statement, allowing the attacker to view unauthorized data. This payload is a common and basic SQL injection technique that injects a logical expression that is always true, such as 'OR 'T="1 or 'OR 1=1, to bypass the authentication or authorization checks of the SQL statement. This payload can allow the attacker to view data that they are not supposed to, such as user credentials, personal information, or financial records. However, this payload does not cause any data loss or modification, and it does not affect the functionality or integrity of the application. * B. 'OR username LIKE '%: This payload uses the LIKE operator to search for a specific pattern in a * column. This payload is a variation of the previous payload that injects a logical expression that is always true, such as 'OR username LIKE '% or 'OR 1 LIKE '%, to bypass the authentication or authorization checks of the SQL statement. The LIKE operator is used to compare a value with a pattern that may contain wildcard characters, such as % or _, which match any string or character. This payload can allow the attacker to view data that matches the pattern, such as usernames that start with a certain letter or contain a certain substring. However, this payload does not cause any data loss or modification, and it does not affect the functionality or integrity of the application. * D. UNION SELECT NULL, NULL, NULL - : This payload manipulates the UNION SQL operator, enabling the attacker to retrieve data from different database tables. This payload is an advanced SQL injection technique that injects the UNION SQL operator to combine the results of two or more SELECT statements into a single result set, which is then returned as part of the HTTP response. The UNION operator can be used to join the results from different tables that have the same number and type of columns. The NULL values are used to match the column types and avoid any errors. This payload can allow the attacker to retrieve data from tables that are not intended to be accessed by the application, such as system tables, configuration tables, or backup tables. However, this payload does not cause any data loss or modification, and it does not affect the functionality or integrity of the application. References: * 1: SQL Injection - OWASP Foundation * 2: SQL Injection Payloads: How SQLi exploits work - Bright Security * 3: SQL Injection - HackTricks
