COMMON ATTACK PATTERN ENUMERATION AND CLASSIFICATIONMITRE canlı kaydı

CAPEC-15

Command Delimiters

An attack of this type exploits a programs' vulnerabilities that allows an attacker's commands to be concatenated onto a legitimate command with the intent of targeting other resources such as the file system or database. The system that uses a filter or denylist input validation, as opposed to allowlist validation is vulnerable to an attacker who predicts delimiters (or combinations of delimiters) not present in the filter or denylist. As with other injection attacks, the attacker uses the command delimiter payload as an entry point to tunnel through the application and activate additional attacks through SQL queries, shell commands, network scanning, and so on.

Soyutlama

Standard

Tipik ciddiyet

High

Saldırı ihtimali

High

Saldırıyı anla

Bu saldırı kalıbı nedir?

An attack of this type exploits a programs' vulnerabilities that allows an attacker's commands to be concatenated onto a legitimate command with the intent of targeting other resources such as the file system or database. The system that uses a filter or denylist input validation, as opposed to allowlist validation is vulnerable to an attacker who predicts delimiters (or combinations of delimiters) not present in the filter or denylist. As with other injection attacks, the attacker uses the command delimiter payload as an entry point to tunnel through the application and activate additional attacks through SQL queries, shell commands, network scanning, and so on.

Uygulama akışı

Saldırı adım adım nasıl ilerler?

1

Explore

Assess Target Runtime Environment

In situations where the runtime environment is not implicitly known, the attacker makes connections to the target system and tries to determine the system's runtime environment. Knowing the environment is vital to choosing the correct delimiters.

Kullanılan teknikler

  • Port mapping using network connection-based software (e.g., nmap, nessus, etc.)
  • Port mapping by exploring the operating system (netstat, sockstat, etc.)
  • TCP/IP Fingerprinting
  • Induce errors to find informative error messages

Survey the Application

The attacker surveys the target application, possibly as a valid and authenticated user

Kullanılan teknikler

  • Spidering web sites for all available links
  • Inventory all application inputs
2

Experiment

Attempt delimiters in inputs

The attacker systematically attempts variations of delimiters on known inputs, observing the application's response each time.

Kullanılan teknikler

  • Inject command delimiters using network packet injection tools (netcat, nemesis, etc.)
  • Inject command delimiters using web test frameworks (proxies, TamperData, custom programs, etc.)
  • Enter command delimiters directly in input fields.
3

Exploit

Use malicious command delimiters

The attacker uses combinations of payload and carefully placed command delimiters to attack the software.

Gereksinimler

Saldırının gerçekleşmesi için ne gerekir?

Ön koşullar

  • Software's input validation or filtering must not detect and block presence of additional malicious command.

Gerekli beceri

  • Medium: The attacker has to identify injection vector, identify the specific commands, and optionally collect the output, i.e. from an interactive session.

Gerekli kaynak

  • Ability to communicate synchronously or asynchronously with server. Optionally, ability to capture output directly through synchronous communication or other method such as FTP.

Etki

Başarılı saldırı neye yol açar?

Execute Unauthorized Commands

Etkilenen alanlar: Confidentiality, Integrity, Availability

Read Data

Etkilenen alanlar: Confidentiality

Savunma

Nasıl önlenir ve etkisi azaltılır?

1
Design: Perform allowlist validation against a positive specification for command length, type, and parameters.
2
Design: Limit program privileges, so if commands circumvent program input validation or filter routines then commands do not running under a privileged account
3
Implementation: Perform input validation for all remote content.
4
Implementation: Use type conversions such as JDBC prepared statements.

Gerçek dünya

MITRE örnek olayları

Örnek olay 1Detay
By appending special characters, such as a semicolon or other commands that are executed by the target process, the attacker is able to execute a wide variety of malicious commands in the target process space, utilizing the target's inherited permissions, against any resource the host has access to. The possibilities are vast including injection attacks against RDBMS (SQL Injection), directory servers (LDAP Injection), XML documents (XPath and XQuery Injection), and command line shells. In many injection attacks, the results are converted back to strings and displayed to the client process such as a web browser without tripping any security alarms, so the network firewall does not log any out of the ordinary behavior. LDAP servers house critical identity assets such as user, profile, password, and group information that is used to authenticate and authorize users. An attacker that can query the directory at will and execute custom commands against the directory server is literally working with the keys to the kingdom in many enterprises. When user, organizational units, and other directory objects are queried by building the query string directly from user input with no validation, or other conversion, then the attacker has the ability to use any LDAP commands to query, filter, list, and crawl against the LDAP server directly in the same manner as SQL injection gives the ability to the attacker to run SQL commands on the database.