The product displays information or identifiers to a user, but the display mechanism does not make it easy for the user to distinguish between visually similar or identical glyphs (homoglyphs), which may cause the user to misinterpret a glyph and perform an unintended, insecure action.
View on MITRESome glyphs, pictures, or icons can be semantically distinct to a program, while appearing very similar or identical to a human user. These are referred to as homoglyphs. For example, the lowercase "l" (ell) and uppercase "I" (eye) have different character codes, but these characters can be displayed in exactly the same way to a user, depending on the font. This can also occur between different character sets. For example, the Latin capital letter "A" and the Greek capital letter "Α" (Alpha) are treated as distinct by programs, but may be displayed in exactly the same way to a user. Accent marks may also cause letters to appear very similar, such as the Latin capital letter grave mark "À" and its equivalent "Á" with the acute accent. Adversaries can exploit this visual similarity for attacks such as phishing, e.g. by providing a link to an attacker-controlled hostname that looks like a hostname that the victim trusts. In a different use of homoglyphs, an adversary may create a back door username that is visually similar to the username of a regular user, which then makes it more difficult for a system administrator to detect the malicious username while reviewing logs.
An attacker may ultimately redirect a user to a malicious website, by deceiving the user into believing the URL they are accessing is a trusted domain. However, the attack can also be used to forge log entries by using homoglyphs in usernames. Homoglyph manipulations are often the first step towards executing advanced attacks such as stealing a user's credentials, Cross-Site Scripting (XSS), or log forgery. If an attacker redirects a user to a malicious site, the attacker can mimic a trusted domain to steal account credentials and perform actions on behalf of the user, without the user's knowledge. Similarly, an attacker could create a username for a website that contains homoglyph characters, making it difficult for an admin to review logs and determine which users performed which actions.
Use a browser that displays Punycode for IDNs in the URL and status bars, or which color code various scripts in URLs. Due to the prominence of homoglyph attacks, several browsers now help safeguard against this attack via the use of Punycode. For example, Mozilla Firefox and Google Chrome will display IDNs as Punycode if top-level domains do not restrict which characters can be used in domain names or if labels mix scripts for different languages.
Use an email client that has strict filters and prevents messages that mix character sets to end up in a user's inbox. Certain email clients such as Google's GMail prevent the use of non-Latin characters in email addresses or in links contained within emails. This helps prevent homoglyph attacks by flagging these emails and redirecting them to a user's spam folder.
If utilizing user accounts, attempt to submit a username that contains homoglyphs. Similarly, check to see if links containing homoglyphs can be sent via email, web browsers, or other mechanisms.
Incomplete denylist does not include homoglyphs of "/" and "?" characters in URLs
View Detailsweb browser does not convert hyphens to punycode, allowing IDN spoofing in URLs
View DetailsNo relationship information available for this CWE.
CWE-1007: Insufficient Visual Distinction of Homoglyphs Presented to User is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product displays information or identifiers to a user, but the display mechanism does not make it easy for the user to distinguish between visually similar or identical glyphs (homoglyphs), which may cause the user to misinterpret a glyph and perform an unintended, insecure action. Some glyphs, pictures, or icons can be semantically distinct to a program, while appearing very similar or identical to a human user. These are referred to as homoglyphs. For example, the lowercase "l" (ell) and uppercase "I" (eye) have different character codes, but these characters can be displayed in exactly the same way to a user, depending on the font. This can also occur between different character sets. For example, the Latin capital letter "A" and the Greek capital letter "Α" (Alpha) are treated as distinct by programs, but may be displayed in exactly the same way to a user. Accent marks may also cause letters to appear very similar, such as the Latin capital letter grave mark "À" and its equivalent "Á" with the acute accent. Adversaries can exploit this visual similarity for attacks such as phishing, e.g. by providing a link to an attacker-controlled hostname that looks like a hostname that the victim trusts. In a different use of homoglyphs, an adversary may create a back door username that is visually similar to the username of a regular user, which then makes it more difficult for a system administrator to detect the malicious username while reviewing logs.
If exploited, CWE-1007 (Insufficient Visual Distinction of Homoglyphs Presented to User) it can compromise Integrity and Confidentiality, leading to outcomes such as Other.
Recommended mitigations for CWE-1007 include: Use a browser that displays Punycode for IDNs in the URL and status bars, or which color code various scripts in URLs. Due to the prominence of homoglyph attacks, several browsers now help safeguard against this attack via the use of Punycode. For example, Mozilla Firefox and Google Chrome will display IDNs as Punycode if top-level domains do not restrict which characters can be used in domain names or if labels mix scripts for different languages. Use an email client that has strict filters and prevents messages that mix character sets to end up in a user's inbox. Certain email clients such as Google's GMail prevent the use of non-Latin characters in email addresses or in links contained within emails. This helps prevent homoglyph attacks by flagging these emails and redirecting them to a user's spam folder.
CWE-1007 can be detected using Manual Dynamic Analysis. Combining automated tooling with manual review typically yields the best coverage.
CWE-1007 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.
MITRE documents real CVEs mapped to CWE-1007, including CVE-2013-7236, CVE-2012-0584, CVE-2009-0652, CVE-2017-5015 and CVE-2005-0233. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.
A CWE (Common Weakness Enumeration) like CWE-1007 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.