CVE-2021-3007 - Deserialization of Untrusted Data

Severity

98%

Complexity

39%

Confidentiality

98%

Zend Framework 3.0.0 has a deserialization vulnerability that can lead to remote code execution if the content is controllable, related to the __destruct method of the Zend\Http\Response\Stream class in Stream.php. NOTE: the code may be related to Laminas Project laminas-http. Zend Framework is no longer supported by the maintainer. However, not all Zend Framework 3.0.0 vulnerabilities exist in a Laminas Project release.

** DISPUTED ** Laminas Project laminas-http before 2.14.2, and Zend Framework 3.0.0, has a deserialization vulnerability that can lead to remote code execution if the content is controllable, related to the __destruct method of the Zend\Http\Response\Stream class in Stream.php. NOTE: Zend Framework is no longer supported by the maintainer. NOTE: the laminas-http vendor considers this a "vulnerability in the PHP language itself" but has added certain type checking as a way to prevent exploitation in (unrecommended) use cases where attacker-supplied data can be deserialized.

CVSS 3.1 Base Score 9.8. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

CVSS 2.0 Base Score 7.5. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (AV:N/AC:L/Au:N/C:P/I:P/A:P).

Demo Examples

Deserialization of Untrusted Data

CWE-502

This code snippet deserializes an object from a file and uses it as a UI button:


               
}
in.close();

This code does not attempt to verify the source or contents of the file before deserializing it. An attacker may be able to replace the intended file with a file that contains arbitrary malicious code which will be executed when the button is pressed.

To mitigate this, explicitly define final readObject() to prevent deserialization. An example of this is:


               
throw new java.io.IOException("Cannot be deserialized"); }

Deserialization of Untrusted Data

CWE-502

In Python, the Pickle library handles the serialization and deserialization processes. In this example derived from [R.502.7], the code receives and parses data, and afterwards tries to authenticate a user based on validating a token.


               
}
raise AuthFail

Unfortunately, the code does not verify that the incoming data is legitimate. An attacker can construct a illegitimate, serialized object "AuthToken" that instantiates one of Python's subprocesses to execute arbitrary commands. For instance,the attacker could construct a pickle that leverages Python's subprocess module, which spawns new processes and includes a number of arguments for various uses. Since Pickle allows objects to define the process for how they should be unpickled, the attacker can direct the unpickle process to call Popen in the subprocess module and execute /bin/sh.

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