Use-after-free in tor.eff Tor

1) Use-after-free

EUVDB-ID: #VU31346

Risk: Medium

CVSSv4.0: 7.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2018-0491

CWE-ID: CWE-416 - Use After Free

Exploit availability: Yes

Description

The vulnerability allows a remote non-authenticated attacker to perform a denial of service (DoS) attack.

A use-after-free issue was discovered in Tor 0.3.2.x before 0.3.2.10. It allows remote attackers to cause a denial of service (relay crash) because the KIST implementation allows a channel to be added more than once in the pending list.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Tor: 0.3.2.1 - 0.3.2.9

CPE2.3

• cpe:2.3:a:tor_eff_org:tor:0.3.2.1:*:*:*:*:*:*:*
• cpe:2.3:a:tor_eff_org:tor:0.3.2.2:*:*:*:*:*:*:*
• cpe:2.3:a:tor_eff_org:tor:0.3.2.3:*:*:*:*:*:*:*

External links

https://blog.torproject.org/new-stable-tor-releases-security-fixes-and-dos-prevention-03210-03110-02915
https://trac.torproject.org/projects/tor/ticket/24700
https://trac.torproject.org/projects/tor/ticket/25117
https://www.exploit-db.com/exploits/44994/

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to trick the victim to visit a specially crafted website.

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.