Heap-based buffer overflow in libvncserver (Alpine package)

1) Heap-based buffer overflow

EUVDB-ID: #VU3076

Risk: Medium

CVSSv3.1: 7.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2016-9941

CWE-ID: CWE-119 - Memory corruption

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on vulnerable client system.

A heap-based buffer overflow vulnerability exists due to boundary error in rfbproto.c in LibVNCClient software, which is bundled with LibVNCServer. A remote attacker can trick the victim to connect to malicious VNC server, send a specially crafted FramebufferUpdate message containing a subrectangle outside of the client drawing area and trigger buffer overflow.

Successful exploitation of the vulnerability may allow an attacker to execute arbitrary code on vulnerable VNC client.

Mitigation

Install update from vendor's website.

Vulnerable software versions

libvncserver (Alpine package): 0.9.10-r0 - 0.9.10-r1

External links

http://git.alpinelinux.org/aports/commit/?id=8cb1ee23b7bc0d719ec7229ba43bf47891d68dbf
http://git.alpinelinux.org/aports/commit/?id=ef8044ed82008b70d1e6fc86b340d60d3c0d16a0
http://git.alpinelinux.org/aports/commit/?id=83306a1e68a975015228808acbbf183570ce3823
http://git.alpinelinux.org/aports/commit/?id=5b2a32c3074c1e9abc0f0490c264335336ffc172
http://git.alpinelinux.org/aports/commit/?id=14594bb55cbbf5113e844d4c8e550fc247ee550a
http://git.alpinelinux.org/aports/commit/?id=09e180651f0e822f8487bf871bcac7b44a2e383a
http://git.alpinelinux.org/aports/commit/?id=f7fc7fd109145de79a4568d1b3f615ba4013b72a

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.