CVE-2023-32698

nFPM is an alternative to fpm. The file permissions on the checked-in files were not maintained. Hence, when nfpm packaged the files (without extra config for enforcing it’s own permissions) files could go out with bad permissions (chmod 666 or 777). Anyone using nfpm for creating packages without checking/setting file permissions before packaging could result in bad permissions for files/folders.

nFPM is an alternative to fpm. The file permissions on the checked-in files were not maintained. Hence, when nfpm packaged the files (without extra config for enforcing it’s own permissions) files could go out with bad permissions (chmod 666 or 777). Anyone using nfpm for creating packages without checking/setting file permissions before packaging could result in bad permissions for files/folders.

Summary

When building packages directly from source control, file permissions on the checked-in files are not maintained.

Details

When building packages directly from source control, file permissions on the checked-in files are not maintained. When nfpm packaged the files (without extra config for enforcing its own permissions) files could go out with bad permissions (chmod 666 or 777).

PoC

Create a default nfpm structure.

Within the test folder, create 3 files named chmod-XXX.sh. Each script has file permissions set corresponding with their file names (chmod-777.sh = chmod 777). Below each file and permissions can be seen.

$ ls -lart test 
total 24
-rwxrwxrwx   1 user  group   11 May 19 13:15 chmod-777.sh
-rw-rw-rw-   1 user  group   11 May 19 13:16 chmod-666.sh
drwxr-xr-x   5 user  group  160 May 19 13:19 .
-rw-rw-r--   1 user  group   11 May 19 13:19 chmod-664.sh
drwxr-xr-x  10 user  group  320 May 19 13:29 ..

Below is the snippet nfpm configuration file of the contents of the package. The test folder and files has no extra config for enforcing permissions.

contents:
- src: foo-binary
  dst: /usr/bin/bar
- src: bar-config.conf
  dst: /etc/foo-binary/bar-config.conf
  type: config
- src: test
  dst: /etc/test/scripts

The next step is to create a deb package.

$ nfpm package -p deb # Create dep package
using deb packager...
created package: foo_1.0.0_arm64.deb

When on a Ubuntu VM, install the foo package which was created

$ sudo dpkg -i foo_1.0.0_arm64.deb # Installing deb package within Ubuntu
Selecting previously unselected package foo.
(Reading database ... 67540 files and directories currently installed.)
Preparing to unpack foo_1.0.0_arm64.deb ...
Unpacking foo (1.0.0) ...
Setting up foo (1.0.0) ...

Looking at /etc/test/scripts and viewing the permissions. Permissions are passed exactly the same as the source.

$ ls -lart /etc/test/scripts
total 20
-rwxrwxrwx 1 root root   11 May 22 12:15 chmod-777.sh
-rw-rw-rw- 1 root root   11 May 22 12:16 chmod-666.sh
-rw-rw-r-- 1 root root   11 May 22 12:19 chmod-664.sh
drwxr-xr-x 3 root root 4096 May 22 13:00 ..
drwxr-xr-x 2 root root 4096 May 22 13:00 .

Solution

To prevent world-writable files from making it into the packages, add the ability to override the default permissions of packaged files using a umask config option in the packaging spec file. This feature in nfpm would allow applying a global umask across any files being packaged, therefore, with the correct configuration, preventing world-writable files without needing to list permissions on each and every file in the package

Impact

Vulnerability is https://cwe.mitre.org/data/definitions/276.html https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Anyone using nfpm for creating packages and not checking/setting file permissions before packaging could result in bad permissions for files/folders.

nFPM is an alternative to fpm. The file permissions on the checked-in files were not maintained. Hence, when nfpm packaged the files (without extra config for enforcing it’s own permissions) files could go out with bad permissions (chmod 666 or 777). Anyone using nfpm for creating packages without checking/setting file permissions before packaging could result in bad permissions for files/folders.

nFPM is an alternative to fpm. The file permissions on the checked-in files were not maintained. Hence, when nfpm packaged the files (without extra config for enforcing it’s own permissions) files could go out with bad permissions (chmod 666 or 777). Anyone using nfpm for creating packages without checking/setting file permissions before packaging could result in bad permissions for files/folders.

Summary

When building packages directly from source control, file permissions on the checked-in files are not maintained.

Details

When building packages directly from source control, file permissions on the checked-in files are not maintained. When nfpm packaged the files (without extra config for enforcing its own permissions) files could go out with bad permissions (chmod 666 or 777).

PoC

Create a default nfpm structure.

Within the test folder, create 3 files named chmod-XXX.sh. Each script has file permissions set corresponding with their file names (chmod-777.sh = chmod 777). Below each file and permissions can be seen.

$ ls -lart test 
total 24
-rwxrwxrwx   1 user  group   11 May 19 13:15 chmod-777.sh
-rw-rw-rw-   1 user  group   11 May 19 13:16 chmod-666.sh
drwxr-xr-x   5 user  group  160 May 19 13:19 .
-rw-rw-r--   1 user  group   11 May 19 13:19 chmod-664.sh
drwxr-xr-x  10 user  group  320 May 19 13:29 ..

Below is the snippet nfpm configuration file of the contents of the package. The test folder and files has no extra config for enforcing permissions.

contents:
- src: foo-binary
  dst: /usr/bin/bar
- src: bar-config.conf
  dst: /etc/foo-binary/bar-config.conf
  type: config
- src: test
  dst: /etc/test/scripts

The next step is to create a deb package.

$ nfpm package -p deb # Create dep package
using deb packager...
created package: foo_1.0.0_arm64.deb

When on a Ubuntu VM, install the foo package which was created

$ sudo dpkg -i foo_1.0.0_arm64.deb # Installing deb package within Ubuntu
Selecting previously unselected package foo.
(Reading database ... 67540 files and directories currently installed.)
Preparing to unpack foo_1.0.0_arm64.deb ...
Unpacking foo (1.0.0) ...
Setting up foo (1.0.0) ...

Looking at /etc/test/scripts and viewing the permissions. Permissions are passed exactly the same as the source.

$ ls -lart /etc/test/scripts
total 20
-rwxrwxrwx 1 root root   11 May 22 12:15 chmod-777.sh
-rw-rw-rw- 1 root root   11 May 22 12:16 chmod-666.sh
-rw-rw-r-- 1 root root   11 May 22 12:19 chmod-664.sh
drwxr-xr-x 3 root root 4096 May 22 13:00 ..
drwxr-xr-x 2 root root 4096 May 22 13:00 .

Solution

To prevent world-writable files from making it into the packages, add the ability to override the default permissions of packaged files using a umask config option in the packaging spec file. This feature in nfpm would allow applying a global umask across any files being packaged, therefore, with the correct configuration, preventing world-writable files without needing to list permissions on each and every file in the package

Impact

Vulnerability is https://cwe.mitre.org/data/definitions/276.html https://www.first.org/cvss/calculator/3.0#CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Anyone using nfpm for creating packages and not checking/setting file permissions before packaging could result in bad permissions for files/folders.

When nfpm packages files without additional configuration to enforce its own permissions, the files could be packaged with incorrect permissions (chmod 666 or 777). Anyone who uses nfpm to create packages and does not check or set file permissions before packaging could result in files or folders being packaged with incorrect permissions.