Multiple vulnerabilities in tor.eff Tor

1) NULL pointer dereference

EUVDB-ID: #VU31386

Risk: Medium

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-8820

CWE-ID: CWE-476 - NULL Pointer Dereference

Exploit availability: No

Description

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

The vulnerability exists due to a NULL pointer dereference error. A remote attacker can trigger denial of service conditions via a malformed descriptor, aka TROVE-2017-010.

Mitigation

Update to version 0.3.1.9.

Vulnerable software versions

Tor: 0.3.1 - 0.3.1.8

External links

http://blog.torproject.org/new-stable-tor-releases-security-fixes-0319-03013-02914-02817-02516
http://bugs.torproject.org/24245
http://www.debian.org/security/2017/dsa-4054

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.

2) Buffer overflow

EUVDB-ID: #VU31387

Risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-8821

CWE-ID: CWE-119 - Memory corruption

Exploit availability: No

Description

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

In Tor before 0.2.5.16, 0.2.6 through 0.2.8 before 0.2.8.17, 0.2.9 before 0.2.9.14, 0.3.0 before 0.3.0.13, and 0.3.1 before 0.3.1.9, an attacker can cause a denial of service (application hang) via crafted PEM input that signifies a public key requiring a password, which triggers an attempt by the OpenSSL library to ask the user for the password, aka TROVE-2017-011.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Tor: 0.3.1 - 0.3.1.8

External links

http://blog.torproject.org/new-stable-tor-releases-security-fixes-0319-03013-02914-02817-02516
http://bugs.torproject.org/24246
http://www.debian.org/security/2017/dsa-4054

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.

3) Use-after-free

EUVDB-ID: #VU31388

Risk: High

CVSSv3.1: 7.1 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-8823

CWE-ID: CWE-416 - Use After Free

Exploit availability: No

Description

The vulnerability allows a remote non-authenticated attacker to execute arbitrary code.

In Tor before 0.2.5.16, 0.2.6 through 0.2.8 before 0.2.8.17, 0.2.9 before 0.2.9.14, 0.3.0 before 0.3.0.13, and 0.3.1 before 0.3.1.9, there is a use-after-free in onion service v2 during intro-point expiration because the expiring list is mismanaged in certain error cases, aka TROVE-2017-013.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Tor: 0.3.1 - 0.3.1.8

External links

http://blog.torproject.org/new-stable-tor-releases-security-fixes-0319-03013-02914-02817-02516
http://bugs.torproject.org/24313
http://bugs.torproject.org/24430
http://www.debian.org/security/2017/dsa-4054

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.