Out-of-bounds write in php7 (Alpine package)

1) Out-of-bounds write

EUVDB-ID: #VU16916

Risk: High

CVSSv3.1: 9 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2019-6977

CWE-ID: CWE-787 - Out-of-bounds write

Exploit availability: Yes

Description

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

The weakness exists due to out-of-bounds write in imagecolormatch. A remote attacker can write up to 1200 bytes over the boundaries of a buffer allocated in the imagecolormatch function, which then calls gdImageColorMatch() and execute arbitrary code with elevated privileges.

Mitigation

Install update from vendor's website.

Vulnerable software versions

php7 (Alpine package): 7.1.17-r0

CPE2.3

• cpe:2.3:o:alpine:php7_alpine_package:7.1.17-r0:*:*:*:*:alpine_linux:*:

External links

http://git.alpinelinux.org/aports/commit/?id=3deb517cec296a32e5b25f1a75a48c2026a44af4
http://git.alpinelinux.org/aports/commit/?id=aad758e364da9a69d0d519b619cc6eb2c7d150f8
http://git.alpinelinux.org/aports/commit/?id=0a3f40e0ea5d2b68f902eb4528b17327939ee400
http://git.alpinelinux.org/aports/commit/?id=2af60a5c6e7e457381ff31c346871e7c51812cfa
http://git.alpinelinux.org/aports/commit/?id=34bc5f16da72bed7c42423c3cfe3cc93fc529c46
http://git.alpinelinux.org/aports/commit/?id=451ff1929d8530ffbceb863acaeb212e545c3080
http://git.alpinelinux.org/aports/commit/?id=478332a5a162445bc68e54ef4138ae2a6af382d8
http://git.alpinelinux.org/aports/commit/?id=d42b915a2245405763bb485ededfbdb01393f109

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.