CAPEC-108: Command Line Execution through SQL Injection
Attack Pattern ID: 108
An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.
Likelihood Of Attack
The table below shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf and ParentOf, and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as CanFollow, PeerOf, and CanAlsoBe are defined to show similar attack patterns that the user may want to explore.
Standard Attack Pattern - A standard level attack pattern in CAPEC is focused on a specific methodology or technique used in an attack. It is often seen as a singular piece of a fully executed attack. A standard attack pattern is meant to provide sufficient details to understand the specific technique and how it attempts to accomplish a desired goal. A standard level attack pattern is a specific type of a more abstract meta level attack pattern.
Probe for SQL Injection vulnerability: The attacker injects SQL syntax into user-controllable data inputs to search unfiltered execution of the SQL syntax in a query.
Achieve arbitrary command execution through SQL Injection with the MSSQL_xp_cmdshell directive: The attacker leverages a SQL Injection attack to inject shell code to be executed by leveraging the xp_cmdshell directive.
Inject malicious data in the database: Leverage SQL injection to inject data in the database that could later be used to achieve command injection if ever used as a command line argument
Trigger command line execution with injected arguments: The attacker causes execution of command line functionality which leverages previously injected database content as arguments.
The application does not properly validate data before storing in the database
Backend application implicitly trusts the data stored in the database
Malicious data is used on the backend as a command line argument
The attacker most likely has to be familiar with the internal functionality of the system to launch this attack. Without that knowledge, there are not many feedback mechanisms to give an attacker the indication of how to perform command injection or whether the attack is succeeding.
None: No specialized resources are required to execute this type of attack.
The table below specifies different individual consequences associated with the attack pattern. The Scope identifies the security property that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in their attack. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a pattern will be used to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Execute Unauthorized Commands
Disable MSSQL xp_cmdshell directive on the database
Properly validate the data (syntactically and semantically) before writing it to the database.
Do not implicitly trust the data stored in the database. Re-validate it prior to usage to make sure that it is safe to use in a given context (e.g. as a command line argument).
SQL injection vulnerability in Cacti 0.8.6i and earlier, when register_argc_argv is enabled, allows remote attackers to execute arbitrary SQL commands via the (1) second or (2) third arguments to cmd.php. NOTE: this issue can be leveraged to execute arbitrary commands since the SQL query results are later used in the polling_items array and popen function (CVE-2006-6799).
A Related Weakness relationship associates a weakness with this attack pattern. Each association implies a weakness that must exist for a given attack to be successful. If multiple weaknesses are associated with the attack pattern, then any of the weaknesses (but not necessarily all) may be present for the attack to be successful. Each related weakness is identified by a CWE identifier.