Insecure deserialization in PEAR Archive_Tar

1) Deserialization of Untrusted Data

EUVDB-ID: #VU17066

Risk: Medium

CVSSv3.1: 3.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N/E:P/RL:O/RC:C]

CVE-ID: CVE-2018-1000888

CWE-ID: CWE-502 - Deserialization of Untrusted Data

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to insecure input validation when processing serialized data within tar files. A remote attacker can create a tar file with `phar://[path_to_malicious_phar_file]` as path  and execute arbitrary code on the target system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Archive_Tar: 1.4.3

External links

http://blog.ripstech.com/2018/new-php-exploitation-technique/
http://cdn2.hubspot.net/hubfs/3853213/us-18-Thomas-It%27s-A-PHP-Unserialization-Vulnerability-Jim-But-Not-As-We-....pdf
http://pear.php.net/bugs/bug.php?id=23782
http://pear.php.net/package/Archive_Tar/download/
http://usn.ubuntu.com/3857-1/
http://www.exploit-db.com/exploits/46108/

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.