CVE-2018-7489 - Deserialization of Untrusted Data

Severity

75%

Complexity

99%

Confidentiality

106%

FasterXML jackson-databind before 2.7.9.3, 2.8.x before 2.8.11.1 and 2.9.x before 2.9.5 allows unauthenticated remote code execution because of an incomplete fix for the CVE-2017-7525 deserialization flaw. This is exploitable by sending maliciously crafted JSON input to the readValue method of the ObjectMapper, bypassing a blacklist that is ineffective if the c3p0 libraries are available in the classpath.

FasterXML jackson-databind before 2.7.9.3, 2.8.x before 2.8.11.1 and 2.9.x before 2.9.5 allows unauthenticated remote code execution because of an incomplete fix for the CVE-2017-7525 deserialization flaw. This is exploitable by sending maliciously crafted JSON input to the readValue method of the ObjectMapper, bypassing a blacklist that is ineffective if the c3p0 libraries are available in the classpath.

CVSS 3.0 Base Score 9.8. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.0/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.

Demo Examples

Incomplete List of Disallowed Inputs

CWE-184

The following code attempts to stop XSS attacks by removing all occurences of "script" in an input string.


               
}
return input.replaceAll("script", mask);

Because the code only checks for the lower-case "script" string, it can be easily defeated with upper-case script tags.

Overview

First reported 6 years ago

2018-02-26 15:29:00

Last updated 5 years ago

2019-09-27 03:15:00

Affected Software

Debian Linux 8.0 (Jessie)

8.0

Debian Linux 9.0

9.0

Red Hat JBoss Enterprise Application Platform 6.4.19

6.4.19

Red Hat JBoss Enterprise Application Platform 7.1.2

7.1.2

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