CVE-2020-27748

A flaw was found in the xdg-email component of xdg-utils-1.1.0-rc1 and newer. When handling mailto: URIs, xdg-email allows attachments to be discreetly added via the URI when being passed to Thunderbird. An attacker could potentially send a victim a URI that automatically attaches a sensitive file to a new email. If a victim user does not notice that an attachment was added and sends the email, this could result in sensitive information disclosure. It has been confirmed that the code behind this issue is in xdg-email and not in Thunderbird.

Weakness

The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.

Affected Software

Potential Mitigations

• Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
• Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/12.html
• https://cwe.mitre.org/data/definitions/217.html
• https://cwe.mitre.org/data/definitions/612.html
• https://cwe.mitre.org/data/definitions/613.html
• https://cwe.mitre.org/data/definitions/618.html
• https://cwe.mitre.org/data/definitions/619.html
• https://cwe.mitre.org/data/definitions/621.html
• https://cwe.mitre.org/data/definitions/622.html
• https://cwe.mitre.org/data/definitions/623.html

References

• https://bugzilla.redhat.com/show_bug.cgi?id=1899769
• https://gitlab.freedesktop.org/xdg/xdg-utils/-/issues/177