Client applications such as web browsers that process HTML data often need to transform data in and out of the XML format by using an XML parser. It may be possible for an attacker to inject data that may have an adverse effect on the XML parser when it is being processed. These adverse effects may include the parser crashing, consuming too much of a resource, executing too slowly, executing code supplied by an attacker, allowing usage of unintended system functionality, etc. An attacker's goal is to leverage parser failure to his or her advantage. In some cases it may be possible to jump from the data plane to the control plane via bad data being passed to an XML parser. [R.484.1]
Likelihood Of Attack
The table(s) below shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf, ParentOf, MemberOf 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.
Relevant to the view "Mechanisms of Attack" (CAPEC-1000)
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.
An attacker determines the input data stream that is being processed by an XML parser on the victim's side.
An attacker crafts input data that may have an adverse effect on the operation of the XML parser when the data is parsed on the victim's system.
An application uses an XML parser to perform transformation on user-controllable data.
An application does not perform sufficient validation to ensure that user-controllable data is safe for an XML parser.
Arbitrary code execution
The client software crashes after visiting a URL downloaded from a hostile server.
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
Carefully validate and sanitize all user-controllable data prior to passing it to the XML parser routine. Ensure that the resultant data is safe to pass to the XML parser.
The client software should have the latest patches and should be audited for vulnerabilities before being used to communicate with potentially hostile servers.
"A remote code execution vulnerability exists in the way that Microsoft Windows parses XML content. The vulnerability may corrupt memory in such a way that an attacker could execute arbitrary code in the context of the logged-on user.
In a web-based attack scenario, an attacker would have to host a website that contains a specially crafted webpage that is used to exploit this vulnerability. An attacker would have no way to force users to visit such a website. Instead, an attacker would have to convince users to visit the website, typically by getting them to click a link in an email message or Instant Messenger message that takes the user to the attackers' website." [R.484.2]
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Page Last Updated or Reviewed:
July 31, 2018
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