Vulnerability Report

CVE-2021-42694

Title: Unicode Homoglyph Identifiers (Trojan Source)

Code Injection

Proof Of Concept

PoC Available for CVE-2021-42694

CWE Category CWE-94
Published Date Nov 01, 2021
Modified Date Nov 21, 2024
Exploit Status Available
Score 8.3 CVSS v3.1
Exploit Probability (EPSS)
8.24%

Vulnerability Summary

CVE-2021-42694: An issue was discovered in the character definitions of the Unicode Specification through 14.0. The specification allows an adversary to produce source code identifiers such as function names using homoglyphs that render visually identical to a target identifier. Adversaries can leverage this to inject code via adversarial identifier definitions in upstream software dependencies invoked deceptively in downstream software. NOTE: the Unicode Consortium offers the following alternative approach to presenting this concern. An issue is noted in the nature of international text that can affect applications that implement support for The Unicode Standard (all versions). Unless mitigated, an adversary could produce source code identifiers using homoglyph characters that render visually identical to but are distinct from a target identifier. In this way, an adversary could inject adversarial identifier definitions in upstream software that are not detected by human reviewers and are invoked deceptively in downstream software. The Unicode Consortium has documented this class of security vulnerability in its document, Unicode Technical Report #36, Unicode Security Considerations. The Unicode Consortium also provides guidance on mitigations for this class of issues in Unicode Technical Standard #39, Unicode Security Mechanisms.

Impacted Vendors

U
unicode 1
U
unicode_project 1

Reference Links

http://www.openwall.com/lists/oss-security/2021/11/01/1 http://www.openwall.com/lists/oss-security/2021/11/01/6 http://www.unicode.org/versions/Unicode14.0.0/ https://cwe.mitre.org/data/definitions/1007.html https://security.gentoo.org/glsa/202210-09 https://trojansource.codes https://www.kb.cert.org/vuls/id/999008 https://www.scyon.nl/post/trojans-in-your-source-code https://www.unicode.org/reports/tr36/ https://www.unicode.org/reports/tr39/ http://www.openwall.com/lists/oss-security/2021/11/01/1 http://www.openwall.com/lists/oss-security/2021/11/01/6 http://www.unicode.org/versions/Unicode14.0.0/ https://cwe.mitre.org/data/definitions/1007.html https://security.gentoo.org/glsa/202210-09 https://trojansource.codes https://www.kb.cert.org/vuls/id/999008 https://www.scyon.nl/post/trojans-in-your-source-code https://www.unicode.org/reports/tr36/ https://www.unicode.org/reports/tr39/
CVSS v3.1
Source Entity [email protected]
Severity HIGH
8.3
Attack Vector
NETWORK
Complexity
HIGH
Privileges
N/A
Interaction
REQUIRED
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
CHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
CVSS v3.1
Source Entity 134c704f-9b21-4f2e-91b3-4a467353bcc0
Severity HIGH
8.3
Attack Vector
NETWORK
Complexity
HIGH
Privileges
N/A
Interaction
REQUIRED
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
CHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
CVSS v2.0
Source Entity [email protected]
Severity MEDIUM
5.1
Access Vector
N/A
Authentication
N/A
RAW VECTOR AV:N/AC:H/Au:N/C:P/I:P/A:P

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2021-42694 Exploits & PoCs (Proof Of Concept)

GitHub https://github.com/simplylu/CVE-2021-42694
View Code
GitHub https://github.com/hffaust/CVE-2021-42574_and_CVE-2021-42694
View Code
GitHub https://github.com/pierDipi/unicode-control-characters-action
View Code
MODIFIED

Vulnerability data or affected products updated.

PUBLISHED

Vulnerability first announced in NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity HIGH
Privileges N/A
Interaction REQUIRED
CVSS Vector String CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H

Affected Stack

No specific products linked.