CVE-2020-5260 - Insufficiently Protected Credentials

Severity

75%

Complexity

39%

Confidentiality

60%

Affected versions of Git have a vulnerability whereby Git can be tricked into sending private credentials to a host controlled by an attacker. Git uses external "credential helper" programs to store and retrieve passwords or other credentials from secure storage provided by the operating system. Specially-crafted URLs that contain an encoded newline can inject unintended values into the credential helper protocol stream, causing the credential helper to retrieve the password for one server (e.g., good.example.com) for an HTTP request being made to another server (e.g., evil.example.com), resulting in credentials for the former being sent to the latter. There are no restrictions on the relationship between the two, meaning that an attacker can craft a URL that will present stored credentials for any host to a host of their choosing. The vulnerability can be triggered by feeding a malicious URL to git clone. However, the affected URLs look rather suspicious; the likely vector would be through systems which automatically clone URLs not visible to the user, such as Git submodules, or package systems built around Git. The problem has been patched in the versions published on April 14th, 2020, going back to v2.17.x. Anyone wishing to backport the change further can do so by applying commit 9a6bbee (the full release includes extra checks for git fsck, but that commit is sufficient to protect clients against the vulnerability). The patched versions are: 2.17.4, 2.18.3, 2.19.4, 2.20.3, 2.21.2, 2.22.3, 2.23.2, 2.24.2, 2.25.3, 2.26.1.

Affected versions of Git have a vulnerability whereby Git can be tricked into sending private credentials to a host controlled by an attacker. Git uses external "credential helper" programs to store and retrieve passwords or other credentials from secure storage provided by the operating system. Specially-crafted URLs that contain an encoded newline can inject unintended values into the credential helper protocol stream, causing the credential helper to retrieve the password for one server (e.g., good.example.com) for an HTTP request being made to another server (e.g., evil.example.com), resulting in credentials for the former being sent to the latter. There are no restrictions on the relationship between the two, meaning that an attacker can craft a URL that will present stored credentials for any host to a host of their choosing. The vulnerability can be triggered by feeding a malicious URL to git clone. However, the affected URLs look rather suspicious; the likely vector would be through systems which automatically clone URLs not visible to the user, such as Git submodules, or package systems built around Git. The problem has been patched in the versions published on April 14th, 2020, going back to v2.17.x. Anyone wishing to backport the change further can do so by applying commit 9a6bbee (the full release includes extra checks for git fsck, but that commit is sufficient to protect clients against the vulnerability). The patched versions are: 2.17.4, 2.18.3, 2.19.4, 2.20.3, 2.21.2, 2.22.3, 2.23.2, 2.24.2, 2.25.3, 2.26.1.

CVSS 3.1 Base Score 7.5. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

CVSS 2.0 Base Score 5. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (AV:N/AC:L/Au:N/C:P/I:N/A:N).

Demo Examples

Insufficiently Protected Credentials

CWE-522

This code changes a user's password.


               
}
SetUserPassword($user, $pass);

While the code confirms that the requesting user typed the same new password twice, it does not confirm that the user requesting the password change is the same user whose password will be changed. An attacker can request a change of another user's password and gain control of the victim's account.

Insufficiently Protected Credentials

CWE-522

The following code reads a password from a properties file and uses the password to connect to a database.


               
...

This code will run successfully, but anyone who has access to config.properties can read the value of password. If a devious employee has access to this information, they can use it to break into the system.

Insufficiently Protected Credentials

CWE-522

The following code reads a password from the registry and uses the password to create a new network credential.


               
...

This code will run successfully, but anyone who has access to the registry key used to store the password can read the value of password. If a devious employee has access to this information, they can use it to break into the system

Insufficiently Protected Credentials

CWE-522

Both of these examples verify a password by comparing it to a stored compressed version.


               
}
return(1);
return(0);

               
}
return(1);
return(0);
//Diagnostic Mode

Because a compression algorithm is used instead of a one way hashing algorithm, an attacker can recover compressed passwords stored in the database.

Insufficiently Protected Credentials

CWE-522

The following examples show a portion of properties and configuration files for Java and ASP.NET applications. The files include username and password information but they are stored in plaintext.

This Java example shows a properties file with a plaintext username / password pair.


               
...# Java Web App ResourceBundle properties file

The following example shows a portion of a configuration file for an ASP.Net application. This configuration file includes username and password information for a connection to a database but the pair is stored in plaintext.


               
...
<add name="ud_DEV" connectionString="connectDB=uDB; uid=db2admin; pwd=password; dbalias=uDB;" providerName="System.Data.Odbc" />

Username and password information should not be included in a configuration file or a properties file in plaintext as this will allow anyone who can read the file access to the resource. If possible, encrypt this information and avoid CWE-260 and CWE-13.

Overview

Type

Debian Linux

First reported 5 years ago

2020-04-14 23:15:00

Last updated 5 years ago

2020-05-06 19:15:00

Affected Software

Debian Linux 8.0 (Jessie)

8.0

Debian Linux 9.0

9.0

Debian Linux 10

10

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