Deserialization in PHP Pear Archive Tar
CVE-2018-1000888
PEAR Archive_Tar version 1.4.3 and earlier contains a CWE-502, CWE-915 vulnerability in the Archive_Tar class. There are several file operations with `$v_header['filename']` as parameter (such as file_exists, is_file, is_dir, etc). When extract is called without a specific prefix path, we can trigger unserialization by crafting a tar file with `phar://[path_to_malicious_phar_file]` as path. Object injection can be used to trigger destruct in the loaded PHP classes, e.g. the Archive_Tar class itself. With Archive_Tar object injection, arbitrary file deletion can occur because `@unlink($this->_temp_tarname)` is called. If another class with useful gadget is loaded, it may possible to cause remote code execution that can result in files being deleted or possibly modified. This vulnerability appears to have been fixed in 1.4.4.
Vulnerability class: Insecure Deserialization
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.191 (97.2th percentile), scored .
Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 97th percentile — 97.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.192 · newest: 0.191 · change: -0.001
Affected products
- PHP Pear Archive Tar
- Canonical Ubuntu Linux — versions 16.04, 18.04, 18.10
- Debian Linux — versions 8.0, 9.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- lists.debian.org/debian-lts-announce/2019/02/msg00020.html (mailing-list, Third Party Advisory)
- usn.ubuntu.com/3857-1/ (vendor-advisory, Third Party Advisory)
- www.debian.org/security/2019/dsa-4378 (vendor-advisory, Third Party Advisory)
- www.exploit-db.com/exploits/46108/ (Exploit, VDB Entry, Third Party Advisory, exploit)
- pear.php.net/package/Archive_Tar/download/ (Third Party Advisory, Broken Link)
- cdn2.hubspot.net/hubfs/3853213/us-18-Thomas-It's-A-PHP-Unserialization-Vulnerab… (Technical Description, Exploit, Third Party Advisory)
- blog.ripstech.com/2018/new-php-exploitation-technique/ (Exploit, Third Party Advisory)
- pear.php.net/bugs/bug.php (Third Party Advisory, Broken Link)
- security.gentoo.org/glsa/202006-14 (vendor-advisory)
Frequently asked questions
- What is CVE-2018-1000888?
- CVE-2018-1000888 is a high-severity vulnerability in PHP Pear Archive Tar, classified under Deserialization of Untrusted Data. CVSS score: 8.8/10. Published 2018-12-28.
- How severe is CVE-2018-1000888?
- High severity. CVSS v3 base score is 8.8 out of 10.
- Is CVE-2018-1000888 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.