All posts by rocco

CWE

CWE-843 – Access of Resource Using Incompatible Type (‘Type Confusion’)

Read Time:54 Second

Description

The program allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.

Modes of Introduction:

– Implementation

Likelihood of Exploit:

 

Related Weaknesses

CWE-704
CWE-704
CWE-119

 

Consequences

Availability, Integrity, Confidentiality: Read Memory, Modify Memory, Execute Unauthorized Code or Commands, DoS: Crash, Exit, or Restart

When a memory buffer is accessed using the wrong type, it could read or write memory out of the bounds of the buffer, if the allocated buffer is smaller than the type that the code is attempting to access, leading to a crash and possibly code execution.

 

Potential Mitigations

CVE References

 

  • CVE-2010-4577
    • Type confusion in CSS sequence leads to out-of-bounds read.
  • CVE-2011-0611
    • Size inconsistency allows code execution, first discovered when it was actively exploited in-the-wild.
  • CVE-2010-0258
    • Improperly-parsed file containing records of different types leads to code execution when a memory location is interpreted as a different object than intended.
CWE

CWE-85 – Doubled Character XSS Manipulations

Read Time:1 Minute, 38 Second

Description

The web application does not filter user-controlled input for executable script disguised using doubling of the involved characters.

Modes of Introduction:

– Implementation

Likelihood of Exploit:

 

Related Weaknesses

CWE-79
CWE-675

 

Consequences

Confidentiality, Integrity, Availability: Read Application Data, Execute Unauthorized Code or Commands

 

Potential Mitigations

Phase: Implementation

Effectiveness:

Description: 

Resolve all filtered input to absolute or canonical representations before processing.

Phase: Implementation

Effectiveness:

Description: 

Carefully check each input parameter against a rigorous positive specification (allowlist) defining the specific characters and format allowed. All input should be neutralized, not just parameters that the user is supposed to specify, but all data in the request, including tag attributes, hidden fields, cookies, headers, the URL itself, and so forth. A common mistake that leads to continuing XSS vulnerabilities is to validate only fields that are expected to be redisplayed by the site. We often encounter data from the request that is reflected by the application server or the application that the development team did not anticipate. Also, a field that is not currently reflected may be used by a future developer. Therefore, validating ALL parts of the HTTP request is recommended.

Phase: Implementation

Effectiveness:

Description: 

Phase: Implementation

Effectiveness:

Description: 

With Struts, write all data from form beans with the bean’s filter attribute set to true.

Phase: Implementation

Effectiveness: Defense in Depth

Description: 

To help mitigate XSS attacks against the user’s session cookie, set the session cookie to be HttpOnly. In browsers that support the HttpOnly feature (such as more recent versions of Internet Explorer and Firefox), this attribute can prevent the user’s session cookie from being accessible to malicious client-side scripts that use document.cookie. This is not a complete solution, since HttpOnly is not supported by all browsers. More importantly, XMLHTTPRequest and other powerful browser technologies provide read access to HTTP headers, including the Set-Cookie header in which the HttpOnly flag is set.

CVE References

 

  • CVE-2002-2086
    • XSS using “