#VU17066 Deserialization of Untrusted Data in Archive_Tar - CVE-2018-1000888

Vulnerability identifier: #VU17066

Vulnerability risk: Medium

CVSSv4.0: 0 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2018-1000888

CWE-ID: CWE-502

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Archive_Tar
Web applications / Other software

Vendor: PHP Group

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

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

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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.