Multiple vulnerabilities in tor.eff Tor



| Updated: 2020-07-17
Risk High
Patch available YES
Number of vulnerabilities 3
CVE-ID CVE-2017-8820
CVE-2017-8821
CVE-2017-8823
CWE-ID CWE-476
CWE-119
CWE-416
Exploitation vector Network
Public exploit N/A
Vulnerable software
 Tor
Client/Desktop applications / Web browsers

Vendor tor.eff.org

Security Bulletin

This security bulletin contains information about 3 vulnerabilities.

1) NULL pointer dereference

EUVDB-ID: #VU31386

Risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

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

CPE2.3 External links

https://blog.torproject.org/new-stable-tor-releases-security-fixes-0319-03013-02914-02817-02516
https://bugs.torproject.org/24245
https://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

CVSSv4.0: 6.6 [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:U/U:Green]

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

CPE2.3 External links

https://blog.torproject.org/new-stable-tor-releases-security-fixes-0319-03013-02914-02817-02516
https://bugs.torproject.org/24246
https://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

CVSSv4.0: 7.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

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

CPE2.3 External links

https://blog.torproject.org/new-stable-tor-releases-security-fixes-0319-03013-02914-02817-02516
https://bugs.torproject.org/24313
https://bugs.torproject.org/24430
https://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.



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