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CAPEC-236: Catching exception throw/signal from privileged block

Attack Pattern ID: 236
Abstraction: Detailed
Status: Draft
Presentation Filter:
+ Description
Attackers can sometimes hijack a privileged thread from the underlying system through synchronous (calling a privileged function that returns incorrectly) or asynchronous (callbacks, signal handlers, and similar) means. Having done so, the Attacker may not only likely access functionality the system's designer didn't intend for them, but they may also go undetected or deny other users essential service in a catastrophic (or insidiously subtle) way.
+ Likelihood Of Attack


+ Typical Severity

Very High

+ Relationships
Section HelpThis table 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.
ChildOfStandard Attack PatternStandard 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.30Hijacking a Privileged Thread of Execution
Section HelpThis table shows the views that this attack pattern belongs to and top level categories within that view.
+ Execution Flow
  1. Attacker determines the underlying system thread that is subject to user-control
  1. Attacker then provides input, perhaps by way of environment variables for the process in question, that affect the executing thread
  1. Upon successful hijacking, the attacker enjoys elevated privileges, and can possibly have the hijacked thread do their bidding
+ Prerequisites
The application in question employs a threaded model of execution with the threads operating at, or having the ability to switch to, a higher privilege level than normal users
In order to feasibly execute this class of attacks, the attacker must have the ability to hijack a privileged thread.
This ability includes, but is not limited to, modifying environment variables that affect the process the thread belongs to, or providing malformed user-controllable input that causes the executing thread to fault and return to a higher privilege level or such.
This does not preclude network-based attacks, but makes them conceptually more difficult to identify and execute.
+ Skills Required
[Level: High]
Hijacking a thread involves knowledge of how processes and threads function on the target platform, the design of the target application as well as the ability to identify the primitives to be used or manipulated to hijack the thread.
+ Resources Required

None: No specialized resources are required to execute this type of attack. The attacker needs to be able to latch onto a privileged thread.

The Attacker does, however, need to be able to program, compile, and link to the victim binaries being executed so that it will turn control of a privileged thread over to the Attacker's malicious code. This is the case even if the attacker conducts the attack remotely.

+ Consequences
Section HelpThis table 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.
Access Control
Gain Privileges
Execute Unauthorized Commands
+ Mitigations
Application Architects must be careful to design callback, signal, and similar asynchronous constructs such that they shed excess privilege prior to handing control to user-written (thus untrusted) code.
Application Architects must be careful to design privileged code blocks such that upon return (successful, failed, or unpredicted) that privilege is shed prior to leaving the block/scope.
+ Example Instances
Attacker targets an application written using Java's AWT, with the 1.2.2 era event model. In this circumstance, any AWTEvent originating in the underlying OS (such as a mouse click) would return a privileged thread. The Attacker could choose to not return the AWT-generated thread upon consuming the event, but instead leveraging its privilege to conduct privileged operations.
+ Content History
Submission DateSubmitterOrganization
2014-06-23CAPEC Content TeamThe MITRE Corporation
Modification DateModifierOrganization
2017-01-09CAPEC Content TeamThe MITRE Corporation
Updated Related_Attack_Patterns
2017-08-04CAPEC Content TeamThe MITRE Corporation
Updated Resources_Required
2020-07-30CAPEC Content TeamThe MITRE Corporation
Updated Execution_Flow
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Page Last Updated or Reviewed: December 17, 2020