NSUnarchiver Read NSBuiltinCharacterSet with Controlled Serialized State

vendor:

MacOS

by:

Project Zero

7,5

CVSS

HIGH

Out-of-bounds Read

125

CWE

Product Name: MacOS

Affected Version From: N/A

Affected Version To: N/A

Patch Exists: YES

Related CWE: N/A

CPE: N/A

Metasploit: N/A

Other Scripts: N/A

Tags: N/A

CVSS Metrics: N/A

Nuclei References: N/A

Nuclei Metadata: N/A

Platforms Tested: MacOS 10.12.3 (16D32)

2017

NSUnarchiver Read NSBuiltinCharacterSet with Controlled Serialized State

Via NSUnarchiver, an attacker can read NSBuiltinCharacterSet with a controlled serialized state. It reads a controlled int using decodeValueOfObjCType:'i' then either passes it to CFCharacterSetGetPredefined or uses it directly to manipulate __NSBuiltinSetTable. Neither path has any bounds checking and the index is used to maniupulate c arrays of pointers.

Mitigation:

Ensure that bounds checking is performed on user-supplied input.

Source

Exploit-DB raw data:

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1170

Via NSUnarchiver we can read NSBuiltinCharacterSet with a controlled serialized state.
It reads a controlled int using decodeValueOfObjCType:"i" then either passes it to
CFCharacterSetGetPredefined or uses it directly to manipulate __NSBuiltinSetTable.
Neither path has any bounds checking and the index is used to maniupulate c arrays of pointers.

Attached python script will generate a serialized NSBuiltinCharacterSet with a value of 42
for the character set identifier.

tested on MacOS 10.12.3 (16D32)


Proof of Concept:
https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/42050.zip