Remote code execution in PuTTY

1) Heap-based buffer overflow

EUVDB-ID: #VU6919

Risk: Medium

CVSSv3.1: 8.1 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2017-6542

CWE-ID: CWE-122 - Heap-based Buffer Overflow

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to execute arbitrary code or cause DoS condition on the target system.

The weakness exists due to heap-based buffer overflow bug in the ssh_agent_channel_data function of PuTTY. A remote attacker can send an agent protocol message containing large length value, connect to the Unix-domain socket representing the forwarded agent connection, trigger memory corruption and execute arbitrary code with privileges o the current user or cause the system to crash.

Successful exploitation of the vulnerability may result in system compromise.

Mitigation

Update to version 0.68 or later.

Vulnerable software versions

PuTTY: 0.52 - 0.67

External links

http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-agent-fwd-overflow.html

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.