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In a Junos Fusion scenario an External Control of Critical State Data vulnerability in the Satellite Device (SD) control state machine of Juniper Networks Junos OS allows an attacker who is able to make physical changes to the cabling of the device to cause a denial of service (DoS). An SD can get rebooted and subsequently controlled by an Aggregation Device (AD) which does not belong to the original Fusion setup and is just connected to an extended port of the SD. To carry out this attack the attacker needs to have physical access to the cabling between the SD and the original AD. This issue affects: Juniper Networks Junos OS 16.1R1 and later versions prior to 18.4R3-S10; 19.1 versions prior to 19.1R3-S7; 19.2 versions prior to 19.2R3-S4. This issue does not affect Juniper Networks Junos OS versions prior to 16.1R1.
CVSS 3.1 Base Score 6.8. CVSS Attack Vector: physical. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
CVSS 2.0 Base Score 4.6. CVSS Attack Vector: local. CVSS Attack Complexity: low. CVSS Vector: (AV:L/AC:L/Au:N/C:P/I:P/A:P).
In the following example, an authentication flag is read from a browser cookie, thus allowing for external control of user state data.
}}authenticated = true;The following code uses input from an HTTP request to create a file name. The programmer has not considered the possibility that an attacker could provide a file name such as "../../tomcat/conf/server.xml", which causes the application to delete one of its own configuration files (CWE-22).
rFile.delete();The following code uses input from a configuration file to determine which file to open and echo back to the user. If the program runs with privileges and malicious users can change the configuration file, they can use the program to read any file on the system that ends with the extension .txt.
out.println(arr);This code prints all of the running processes belonging to the current user.
system($command);//assume getCurrentUser() returns a username that is guaranteed to be alphanumeric (CWE-78)This program is also vulnerable to a PATH based attack (CWE-426), as an attacker may be able to create malicious versions of the ps or grep commands. While the program does not explicitly raise privileges to run the system commands, the PHP interpreter may by default be running with higher privileges than users.
The following code segment implements a basic server that uses the "ls" program to perform a directory listing of the directory that is listed in the "HOMEDIR" environment variable. The code intends to allow the user to specify an alternate "LANG" environment variable. This causes "ls" to customize its output based on a given language, which is an important capability when supporting internationalization.
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}$ENV{$1} = $2;close($fh);SendOutput($stream, "FILEINFO: $_");The programmer takes care to call a specific "ls" program and sets the HOMEDIR to a fixed value. However, an attacker can use a command such as "ENV HOMEDIR /secret/directory" to specify an alternate directory, enabling a path traversal attack (CWE-22). At the same time, other attacks are enabled as well, such as OS command injection (CWE-78) by setting HOMEDIR to a value such as "/tmp; rm -rf /". In this case, the programmer never intends for HOMEDIR to be modified, so input validation for HOMEDIR is not the solution. A partial solution would be a whitelist that only allows the LANG variable to be specified in the ENV command. Alternately, assuming this is an authenticated user, the language could be stored in a local file so that no ENV command at all would be needed.
While this example may not appear realistic, this type of problem shows up in code fairly frequently. See CVE-1999-0073 in the observed examples for a real-world example with similar behaviors.
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