metamail contains multiple format string vulnerabilities

2004-02-2400:00:00

www.kb.cert.org

7.5 High

CVSS2

Access Vector

NETWORK

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:L/Au:N/C:P/I:P/A:P

0.926 High

EPSS

Percentile

99.0%

JSON

Overview

Multiple format string vulnerabilities in the metamail package could allow a remote attacker to execute arbitrary code on the vulnerable system. An attacker may be able to exploit these vulnerabilities via a specially-crafted email message.

Description

The metamail package is one of the first widely adopted packages developed to handle Multipurpose Internet Mail Extensions (MIME) data, and includes a number of programs for handling various MIME types. Although it is mostly historic, it is still in wide deployment in many environments. Two format string vulnerabilities have been discovered in various portions of the metamail codebase. According to an analysis published by Ulf Härnhammar:

The first format string bug occurs when a message has a “multipart/alternative” media type and one of the body parts has a “Content-Type” header with parameter names or values containing formatting codes. It occurs because of two bad _fprintf()_ statements in the function _SaveSquirrelFile()_ - yes, it’s really called that - in metamail.c. […]

The second format string bug occurs when a message has encoded non-ASCII characters in the mail headers (as described in RFC 2047), an unknown encoding, and encoded text containing formatting codes. It is caused by a bad _printf()_ statement in the function _PrintHeader()_ in metamail.c. […]

Although programs included in the metamail package can be invoked explicitly by a user from the command line, they are commonly invoked automatically by a mail reader or intermediate mail handling applications. Examples of such applications include, but are not limited to, virus scanners, spam filtering software, and mail delivery agents such as procmail. This is an important consideration since messages containing malicious code may be automatically or inadvertently passed to metamail in these cases.

**NOTE:**Proof-of-concept exploit code has been published for this vulnerability.

Impact

An attacker may be able to execute code of their choosing on a vulnerable system by introducing a specially-crafted MIME attachment. The code would be executed in the context of the user who invoked the metamail program or mail handling program that launched metamail.

Solution

Apply a patch from the vendor

Although the metamail package is unmaintained by the original author, some redistributors have released patches. Please see the Systems Affected section of this document for more details.

Vendor Information

518518

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The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The Slackware security team has published Slackware Security Advisory SSA:2004-049-02 in response to this issue. Users are encouraged to review this advisory and apply the patches it refers to.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23518518 Feedback>).