Web Application Security and IPSec


Web application security is the process of securing confidential data stored online from unauthorized access and modification. This is accomplished by enforcing stringent policy measures. Security threats can compromise the data stored by an organization is hackers with malicious intentions try to gain access to sensitive information.
The aim of Web application security is to identify the following:

  • Critical assets of the organization
  • Genuine users who may access the data
  • Level of access provided to each user
  • Various vulnerabilities that may exist in the application
  • Data criticality and risk analysis on data exposure
  • Appropriate remediation measures

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Most commonly, the following tactics are used in to attack these applications:

  • SQL Injection
  • XSS (Cross Site Scripting)
  • Remote Command Execution
  • Path Traversal

1)SQL Injection: SQL injection is a type of security exploit in which the attacker adds Structured Query Language (SQL) code to a Web form input box to gain access to resources or make changes to data. An SQL query is a request for some action to be performed on a database. Typically, on a Web form for user authentication, when a user enters their name and password into the text boxes provided for them, those values are inserted into a SELECT query. If the values entered are found as expected, the user is allowed access; if they aren’t found, access is denied. However, most Web forms have no mechanisms in place to block input other than names and passwords. Unless such precautions are taken, an attacker can use the input boxes to send their own request to the database, which could allow them to download the entire database or interact with it in other illicit ways and by injecting a SQL statement, like ‘ ) OR 1=1–, the attacker can access information stored in the web site’s database. Of course, the example used above represents a relatively simple SQL statement. Ones used by attackers are often much more sophisticated if they know what the tables in the database are since these complex statements can generally produce better results.

SQL injection is mostly known as an attack vector for websites.

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2)Cross Site Scripting: Cross-Site Scripting (XSS) attacks are a type of injection, in which malicious scripts are injected into otherwise benign and trusted web sites. XSS attacks occur when an attacker uses a web application to send malicious code, generally in the form of a browser side script, to a different end user. Flaws that allow these attacks to succeed are quite widespread and occur anywhere a web application uses input from a user within the output it generates without validating or encoding it.An attacker can use XSS to send a malicious script to an unsuspecting user. The end user’s browser has no way to know that the script should not be trusted, and will execute the script. Because it thinks the script came from a trusted source, the malicious script can access any cookies, session tokens, or other sensitive information retained by the browser and used with that site. These scripts can even rewrite the content of the HTML page.

Image result for xss attack3)Remote Command Execution:Remote Command Execution vulnerabilities allow attackers to pass arbitrary commands to other applications. In severe cases, the attacker can obtain system level privileges allowing them to attack the servers from a remote location and execute whatever commands they need for their attack to be successful.

4)Path Traversal:Path Traversal vulnerabilities give the attacker access to files, directories, and commands that generally are not accessible because they reside outside the normal realm of the web document root directory. Unlike the other vulnerabilities discussed, Path Traversal exploits exist due to a security design error – not a coding error.

HTTPS was originally used mainly to secure sensitive web traffic such as financial transactions, but it is now common to see it used by default on many sites we use in our day to day lives such as social networking and search engines. The HTTPS protocol uses the Transport Layer Security (TLS) protocol, the successor to the Secure Sockets Layer (SSL) protocol, to secure communications. When configured and used correctly, it provides protection against eavesdropping and tampering, along with a reasonable guarantee that a website is the one we intend to be using. Or, in more technical terms, it provides confidentiality and data integrity, along with authentication of the website’s identity.

IPSec:IPsec (Internet Protocol Security) is a framework for a set of protocols for security at the network or packet processing layer of network communication. It is an Internet Engineering Task Force (IETF) standard suite of protocols that provides data authentication, integrity, and confidentiality as data is transferred between communication points across IP networks. IPSec provides data security at the IP packet level. A packet is a data bundle that is organized for transmission across a network, and it includes a header and payload (the data in the packet). IPSec emerged as a viable network security standard because enterprises wanted to ensure that data could be securely transmitted over the Internet. IPSec protects against possible security exposures by protecting data while in transit.

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IPSec contains the following elements:

1)Encapsulating Security Payload (ESP): Encapsulating Security Payload (ESP) is a member of the IPsec protocol suite. In IPsec it provides origin authenticity, integrity and confidentiality protection of packets. ESP also supports encryption-only and authentication-only configurations, but using encryption without authentication is strongly discouraged because it is insecure.Unlike Authentication Header (AH), ESP in transport mode does not provide integrity and authentication for the entire IP packet. However, in Tunnel Mode, where the entire original IP packet is encapsulated with a new packet header added, ESP protection is afforded to the whole inner IP packet (including the inner header) while the outer header (including any outer IPv4 options or IPv6 extension headers) remains unprotected. ESP operates directly on top of IP, using IP protocol number 50.


The ESP header contains the following fields:

  • Security Parameters Index    Identifies, when used in combination with the destination address and the security protocol (AH or ESP), the correct security association for the communication. The receiver uses this value to determine the security association with which this packet should be identified.
  • Sequence Number    Provides anti-replay protection for the SA. It is 32-bit, incrementally increasing number (starting from 1) that indicates the packet number sent over the security association for the communication. The sequence number is never allowed to cycle. The receiver checks this field to verify that a packet for a security association with this number has not been received already. If one has been received, the packet is rejected.

The ESP trailer contains the following fields:

  • Padding    0 to 255 bytes is used for 32-bit alignment and with the block size of the block cipher.
  • Padding Length    Indicates the length of the Padding field in bytes. This field is used by the receiver to discard the Padding field.
  • Next Header    Identifies the nature of the payload, such as TCP or UDP.

The ESP Authentication Trailer contains the following field:

Authentication Data    Contains the Integrity Check Value (ICV), and a message authentication code that is used to verify the sender’s identity and message integrity. The ICV is calculated over the ESP header, the payload data and the ESP trailer.

2)Authentication Header (AH):Authentication Header (AH) is a member of the IPsec protocol suite. AH guarantees connectionless integrity and data origin authentication of IP packets. Further, it can optionally protect against replay attacks by using the sliding window technique and discarding old packets (see below).

  • In IPv4, the AH protects the IP payload and all header fields of an IP datagram except for mutable fields (i.e. those that might be altered in transit), and also IP options such as the IP Security Option (RFC 1108). Mutable (and therefore unauthenticated) IPv4 header fields are DSCP/ToS, ECN, Flags, Fragment Offset, TTL and Header Checksum.
  • In IPv6, the AH protects most of the IPv6 base header, AH itself, non-mutable extension headers after the AH, and the IP payload. Protection for the IPv6 header excludes the mutable fields: DSCP, ECN, Flow Label, and Hop Limit.

AH operates directly on top of IP, using IP protocol number 51.

3)Internet Key Exchange (IKE): The Internet Key Exchange (IKE) is an IPsec (Internet Protocol Security) standard protocol used to ensure security for virtual private network (VPN) negotiation and remote host or network access. Specified in IETF Request for Comments (RFC) 2409, IKE defines an automatic means of negotiation and authentication for IPsec security associations (SA). Security associations are security policies defined for communication between two or more entities; the relationship between the entities is represented by a key. The IKE protocol ensures security for SA communication without the preconfiguration that would otherwise be required.

Benefits provided by IKE include:

  • Eliminates the need to manually specify all the IPSec security parameters in the crypto maps at both peers.
  • Allows you to specify a lifetime for the IPSec security association.
  • Allows encryption keys to change during IPSec sessions.
  • Allows IPSec to provide anti-replay services.
  • Permits Certification Authority (CA) support for a manageable, scalable IPSec implementation.
  • Allows dynamic authentication of peers.