Remote code execution in FortiOS sslvpnd

1) Heap-based buffer overflow

EUVDB-ID: #VU70120

Risk: Critical

CVSSv3.1: 9.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2022-42475

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

Exploit availability: Yes

Description

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

The vulnerability exists due to a boundary error within the sslvpnd daemon. A remote non-authenticated attacker can pass specially crafted data to the SSL-VPN interface, trigger a heap-based buffer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Note, the vulnerability is being actively exploited in the wild.

Mitigation

Install updates from vendor's website.

It is also advised by the vendor to check your system for the following indicators of compromise:

Multiple log entries with:

Logdesc="Application crashed" and msg="[...] application:sslvpnd,[...], Signal 11 received, Backtrace: [...]“

 

Presence of the following artifacts in the filesystem:

/data/lib/libips.bak
/data/lib/libgif.so
/data/lib/libiptcp.so
/data/lib/libipudp.so
/data/lib/libjepg.so
/var/.sslvpnconfigbk
/data/etc/wxd.conf
/flash

 

Connections to suspicious IP addresses from the FortiGate:

188.34.130.40:444
103.131.189.143:30080,30081,30443,20443
192.36.119.61:8443,444
172.247.168.153:8033

Vulnerable software versions

FortiOS: 6.2.0 - 7.2.2

External links

http://fortiguard.fortinet.com/psirt/FG-IR-22-398

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?

Yes. This vulnerability is being exploited in the wild.