CVE-2023-35845: CVE-2023-35845: Anaconda3 creates numerous world-writable files on install

Background

Well over a year ago I installed Anaconda3 on my laptop for some work. When the installation completed I noticed that numerous files had been installed world-writable. This is less then ideal obviously but it was my laptop so I fixed the issue and moved on. Fast-forward to September 2022 and I’m left cleaning up these issues after every upgrade or install at a customer site. This is where I become annoyed that this issue still hasn’t been resolved so I figured I better report it.

After an unacceptably long delay to try to get resolution of this issue I am publishing the details.

**Technical Details
**

Installing any version of the Anaconda or Miniconda on Linux results in numerous world-writable files. For example, below I took the latest version from the website and performed the batch (no prompt) install to $HOME/anaconda3:

[jeremy@test1 ~]$ bash Anaconda3-2023.03-1-Linux-x86_64.sh -b -p $HOME/anaconda3
PREFIX=/home/jeremy/anaconda3
Unpacking payload …

Installing base environment…

Downloading and Extracting Packages

Downloading and Extracting Packages

Preparing transaction: done
Executing transaction: |

Installed package of scikit-learn can be accelerated using scikit-learn-intelex.  
More details are available here: https://intel.github.io/scikit-learn-intelex

For example:

    $ conda install scikit-learn-intelex  
    $ python -m sklearnex my\_application.py

done
installation finished.

With the installation finished I ran a quick check of the permissions for files and directories with the other writable bit set. As you can see from the two commands below they are all files. Previously I have found directories as well.

[jeremy@test1 ~]$ find /home/jeremy/anaconda3 -perm /0002 \( -type f -o -type d \) | wc
606 606 58235
[jeremy@test1 ~]$ find /home/jeremy/anaconda3 -perm /0002 -type f | wc
606 606 58235

To see what those files look like permission wise you can run a find command filtering for files that are world-writable with the "-perm /0002" option:

[jeremy@test1 ~]$ find /home/jeremy/anaconda3 -perm /0002 -type f -ls
3773199 92 -rwxrwxrwx 2 jeremy jeremy 91648 Nov 5 2022 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/distlib/w32.exe
3773231 108 -rwxrwxrwx 2 jeremy jeremy 108032 Nov 5 2022 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/distlib/t64.exe
3773242 168 -rwxrwxrwx 2 jeremy jeremy 168448 Nov 5 2022 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/distlib/w64-arm.exe
3773208 96 -rwxrwxrwx 2 jeremy jeremy 97792 Nov 5 2022 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/distlib/t32.exe
3773215 100 -rwxrwxrwx 2 jeremy jeremy 101888 Nov 5 2022 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/distlib/w64.exe
3773253 180 -rwxrwxrwx 2 jeremy jeremy 182784 Nov 5 2022 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/distlib/t64-arm.exe
3773149 4 -rw-rw-rw- 2 jeremy jeremy 469 Nov 5 2022 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/vendor.txt
3773176 280 -rw-rw-rw- 2 jeremy jeremy 286370 Nov 5 2022 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/certifi/cacert.pem
3773161 4 -rw-rw-rw- 2 jeremy jeremy 286 Nov 5 2022 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/py.typed
3773169 4 -rw-rw-rw- 2 jeremy jeremy 4072 Dec 9 2022 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip-22.3.1-py3.10.egg-info/PKG-INFO
…
3713940 4 -rwxrwxrwx 1 jeremy jeremy 740 Aug 31 2020 /home/jeremy/anaconda3/pkgs/libllvm10-10.0.1-hbcb73fb_5/info/recipe/parent/install_llvm.bat
3714015 4 -rwxrwxrwx 1 jeremy jeremy 1387 Aug 31 2020 /home/jeremy/anaconda3/pkgs/libllvm10-10.0.1-hbcb73fb_5/info/recipe/parent/install_llvm.sh
3713958 4 -rwxrwxrwx 1 jeremy jeremy 726 Sep 4 2020 /home/jeremy/anaconda3/pkgs/libllvm10-10.0.1-hbcb73fb_5/info/recipe/parent/xcode-select
3714009 4 -rwxrwxrwx 1 jeremy jeremy 1387 Aug 31 2020 /home/jeremy/anaconda3/pkgs/libllvm10-10.0.1-hbcb73fb_5/info/recipe/install_llvm.sh
3657118 4 -rwxrwxrwx 1 jeremy jeremy 3364 Jan 5 2021 /home/jeremy/anaconda3/pkgs/jupyterlab_widgets-1.0.0-pyhd3eb1b0_1/info/recipe/recipe_log.txt
3657112 4 -rwxrwxrwx 1 jeremy jeremy 828 Jan 5 2021 /home/jeremy/anaconda3/pkgs/jupyterlab_widgets-1.0.0-pyhd3eb1b0_1/info/recipe/meta.yaml.template
3279942 4 -rwxrwxrwx 1 jeremy jeremy 1923 Jun 13 2019 /home/jeremy/anaconda3/pkgs/backports.weakref-1.0.post1-py_1/info/recipe/recipe_log.txt
3279943 4 -rwxrwxrwx 1 jeremy jeremy 1091 Jun 12 2019 /home/jeremy/anaconda3/pkgs/backports.weakref-1.0.post1-py_1/info/recipe/meta.yaml.template
3709519 8 -rwxrwxrwx 1 jeremy jeremy 4402 May 4 2020 /home/jeremy/anaconda3/pkgs/atomicwrites-1.4.0-py_0/info/recipe/recipe_log.txt
3709528 4 -rwxrwxrwx 1 jeremy jeremy 774 May 4 2020 /home/jeremy/anaconda3/pkgs/atomicwrites-1.4.0-py_0/info/recipe/meta.yaml.template

I’m not sure how frequently if ever these files are used but one file stuck out to me when I reviewed the list. The cacert.pem file used by the python certify module under their pip installation. Since certify provides the trusted root certificate authorities, any manipulation of these could allow untrusted content to pass through SSL connections via Man-in-the-middle attack. You can see below there are two files found but since they are the same inode number we know they are actually a hardlink:

[jeremy@test1 ~]$ find /home/jeremy/anaconda3 -type f -perm /0002 -name cacert.pem -ls
1986492 280 -rw-rw-rw- 2 jeremy jeremy 286370 Nov 5 2022 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/certifi/cacert.pem
1986492 280 -rw-rw-rw- 2 jeremy jeremy 286370 Nov 5 2022 /home/jeremy/anaconda3/pkgs/pip-22.3.1-py310h06a4308_0/lib/python3.10/site-packages/pip/_vendor/certifi/cacert.pem

For illustrations purposes here I created and used a different account (test) to truncate the cacert.pem files and show they have been truncated to 0 bytes.

[test@test1 ~]$ find /home/jeremy/anaconda3/ -type f -perm /0002 -name cacert.pem -ls
1986492 280 -rw-rw-rw- 2 jeremy jeremy 286370 Nov 5 2022 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/certifi/cacert.pem
1986492 280 -rw-rw-rw- 2 jeremy jeremy 286370 Nov 5 2022 /home/jeremy/anaconda3/pkgs/pip-22.3.1-py310h06a4308_0/lib/python3.10/site-packages/pip/_vendor/certifi/cacert.pem
[test@test1 ~]$ truncate --size=0 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/certifi/cacert.pem
[test@test1 ~]$ find /home/jeremy/anaconda3/ -type f -perm /0002 -name cacert.pem -ls
1986492 0 -rw-rw-rw- 2 jeremy jeremy 0 Jun 5 17:28 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/certifi/cacert.pem
1986492 0 -rw-rw-rw- 2 jeremy jeremy 0 Jun 5 17:28 /home/jeremy/anaconda3/pkgs/pip-22.3.1-py310h06a4308_0/lib/python3.10/site-packages/pip/_vendor/certifi/cacert.pem

Moving back to my normal user, if these files are used by the Anaconda3 packaged version of pip this should result in SSL error:

[jeremy@test1 ~]$ /home/jeremy/anaconda3/bin/pip install tensorflow==
WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(136, '[X509: NO_CERTIFICATE_OR_CRL_FOUND] no certificate or crl found (_ssl.c:4123)'))': /simple/tensorflow/
WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(136, '[X509: NO_CERTIFICATE_OR_CRL_FOUND] no certificate or crl found (_ssl.c:4123)'))': /simple/tensorflow/
WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(136, '[X509: NO_CERTIFICATE_OR_CRL_FOUND] no certificate or crl found (_ssl.c:4123)'))': /simple/tensorflow/
WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(136, '[X509: NO_CERTIFICATE_OR_CRL_FOUND] no certificate or crl found (_ssl.c:4123)'))': /simple/tensorflow/
WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(136, '[X509: NO_CERTIFICATE_OR_CRL_FOUND] no certificate or crl found (_ssl.c:4123)'))': /simple/tensorflow/
Could not fetch URL https://pypi.org/simple/tensorflow/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host=’pypi.org’, port=443): Max retries exceeded with url: /simple/tensorflow/ (Caused by SSLError(SSLError(136, '[X509: NO_CERTIFICATE_OR_CRL_FOUND] no certificate or crl found (_ssl.c:4123)'))) - skipping
ERROR: Could not find a version that satisfies the requirement tensorflow== (from versions: none)
ERROR: No matching distribution found for tensorflow==

As you can see we do in fact get an error that no valid cert is found. This is due to the truncated root CA certs file. Clearly there are significant risks besides a Denial of Service (DoS) from Anaconda’s creation of these world-writable files.

Disclosure Timeline:

• Sep 22, 2022 - Reported world-writable vulnerability including list of files

• Sep 22, 2022 - Confirmation from Anaconda

• Sep 23, 2022 - Provided an easy way to reproduce to Anaconda

• Sep 23, 2022 - Anaconda confirms reproducer and says “We are working on a fix for this issue and will notify you. once a fix is available”

• Nov 16, 2022 - I request status update

• Nov 16, 2022 - Anaconda responds "Our security team is taking a look at this issue this week and we can give you a better time frame estimation once this has been completed. "

• Nov 23, 2022 - Anaconda updates “Our security group has reviewed this issue, and are prioritizing it for a future sprint cycle”

• Jan 31, 2023 - With no response from Anaconda I test and the issue still exists. At this point I research if a CVE is filed and find similar (though not the sames) issues in Windows reported as: CVE-2022-26526.

• Feb 20, 2023 - Anaconda responds that CVE-2022-26526 is fixed but the issue I reported "is unfortunately not a straightforward fix".

• Feb 28, 2023 - I respond that any proper fix should take into account the user’s umask during installation.

• Feb 28, 2023 - Anaconda acknowledges my umask email

• Jun 1, 2023 - I inquire again for the status of a fix

• Jun 1, 2023 - Anaconda erroneously believes “fixes for this implemented in Anaconda 2022.05 and Miniconda3 4.12.0 and beyond”

• Jun 2, 2023 - I verify Linux is still vulnerable and email them to let them know

• Jun 2, 2023 - I finally file for a CVE with MITRE as the CNA-LR

• Jun 18, 2023 - MITRE rerves CVE-2023-35845 for this issue

• Jun 22, 2023 - I provide one more email to Anaconda notifying them of the impending CVE and receive no response as of this writing on Jun 27.

Solutions

Given this information it’s clear that there are risks and possibly significant risks besides a Denial of Service (DoS) from Anaconda’s creation of these world-writable files. Luckily if you already upgraded the pip packaged with Anaconda it appears to fix this world-writable cacert.pem file limiting the one illustrated path to exploitation here:

[jeremy@test1 ~]$ $HOME/anaconda3/bin/pip install --upgrade pip
Requirement already satisfied: pip in ./anaconda3/lib/python3.10/site-packages (22.3.1)
Collecting pip
Using cached pip-23.1.2-py3-none-any.whl (2.1 MB)
Installing collected packages: pip
Attempting uninstall: pip
Found existing installation: pip 22.3.1
Uninstalling pip-22.3.1:
Successfully uninstalled pip-22.3.1
Successfully installed pip-23.1.2

You can see there does exist one of the cacert.pem file but this is not the one used by the Anaconda3 pip (a utility detailed below confirmed that for me):

[jeremy@test1 ~]$ find $HOME/anaconda3 -type f -perm /0002 -name cacert.pem -ls
3773176 280 -rw-rw-rw- 1 jeremy jeremy 286370 Nov 5 2022 /home/jeremy/anaconda3/pkgs/pip-22.3.1-py310h06a4308_0/lib/python3.10/site-packages/pip/_vendor/certifi/cacert.pem

Regardless of the pip solution the best strategy for now appears to be to strip all “other” write permissions from your Anaconda3 installation directory any time you install or update software:

[jeremy@test1 ~]$ find $HOME/anaconda3 -type f -perm /0002 -exec chmod o-w {} \;

**Detection of Similar Problems
**

Finally, if your interested in a utility to capture information about what opens, executes, or changes permissions to create world-writable I’ve create an eBPF program to help identify that and stored in my github repo here:

https://github.com/jfilizetti/ebpf-security-tools

Here is an example capture of the cacert.pem described above:

[root@test1 jeremy]# ./world_writable_monitor.py -f regular,directory | grep cacert.pem
chmod 666 1000:1000 93877 conda.exe 0 -100 /home/jeremy/anaconda3/pkgs/pip-22.3.1-py310h06a4308_0/lib/python3.10/site-packages/pip/_vendor/certifi/cacert.pem
open 666 1000:1000 93910 pip 0 -100 /home/jeremy/anaconda3/lib/python3.10/site-packages/pip/_vendor/certifi/cacert.pem