CVE-2024-45405

gix-path is a crate of the gitoxide project (an implementation of git written in Rust) dealing paths and their conversions. Prior to version 0.10.11, gix-path runs git to find the path of a configuration file associated with the git installation, but improperly resolves paths containing unusual or non-ASCII characters, in rare cases enabling a local attacker to inject configuration leading to code execution. Version 0.10.11 contains a patch for the issue.

In gix_path::env, the underlying implementation of the installation_config and installation_config_prefix functions calls git config -l --show-origin to find the path of a file to treat as belonging to the git installation. Affected versions of gix-path do not pass -z/--null to cause git to report literal paths. Instead, to cover the occasional case that git outputs a quoted path, they attempt to parse the path by stripping the quotation marks. The problem is that, when a path is quoted, it may change in substantial ways beyond the concatenation of quotation marks. If not reversed, these changes can result in another valid path that is not equivalent to the original.

On a single-user system, it is not possible to exploit this, unless GIT_CONFIG_SYSTEM and GIT_CONFIG_GLOBAL have been set to unusual values or Git has been installed in an unusual way. Such a scenario is not expected. Exploitation is unlikely even on a multi-user system, though it is plausible in some uncommon configurations or use cases. In general, exploitation is more likely to succeed if users are expected to install git themselves, and are likely to do so in predictable locations; locations where git is installed, whether due to usernames in their paths or otherwise, contain characters that git quotes by default in paths, such as non-English letters and accented letters; a custom system-scope configuration file is specified with the GIT_CONFIG_SYSTEM environment variable, and its path is in an unusual location or has strangely named components; or a system-scope configuration file is absent, empty, or suppressed by means other than GIT_CONFIG_NOSYSTEM. Currently, gix-path can treat a global-scope configuration file as belonging to the installation if no higher scope configuration file is available. This increases the likelihood of exploitation even on a system where git is installed system-wide in an ordinary way. However, exploitation is expected to be very difficult even under any combination of those factors.

gix-path is a crate of the gitoxide project (an implementation of git written in Rust) dealing paths and their conversions. Prior to version 0.10.11, gix-path runs git to find the path of a configuration file associated with the git installation, but improperly resolves paths containing unusual or non-ASCII characters, in rare cases enabling a local attacker to inject configuration leading to code execution. Version 0.10.11 contains a patch for the issue.

In gix_path::env, the underlying implementation of the installation_config and installation_config_prefix functions calls git config -l --show-origin to find the path of a file to treat as belonging to the git installation. Affected versions of gix-path do not pass -z/--null to cause git to report literal paths. Instead, to cover the occasional case that git outputs a quoted path, they attempt to parse the path by stripping the quotation marks. The problem is that, when a path is quoted, it may change in substantial ways beyond the concatenation of quotation marks. If not reversed, these changes can result in another valid path that is not equivalent to the original.

On a single-user system, it is not possible to exploit this, unless GIT_CONFIG_SYSTEM and GIT_CONFIG_GLOBAL have been set to unusual values or Git has been installed in an unusual way. Such a scenario is not expected. Exploitation is unlikely even on a multi-user system, though it is plausible in some uncommon configurations or use cases. In general, exploitation is more likely to succeed if users are expected to install git themselves, and are likely to do so in predictable locations; locations where git is installed, whether due to usernames in their paths or otherwise, contain characters that git quotes by default in paths, such as non-English letters and accented letters; a custom system-scope configuration file is specified with the GIT_CONFIG_SYSTEM environment variable, and its path is in an unusual location or has strangely named components; or a system-scope configuration file is absent, empty, or suppressed by means other than GIT_CONFIG_NOSYSTEM. Currently, gix-path can treat a global-scope configuration file as belonging to the installation if no higher scope configuration file is available. This increases the likelihood of exploitation even on a system where git is installed system-wide in an ordinary way. However, exploitation is expected to be very difficult even under any combination of those factors.

Summary

gix-path runs git to find the path of a configuration file associated with the git installation, but improperly resolves paths containing unusual or non-ASCII characters, in rare cases enabling a local attacker to inject configuration leading to code execution.

Details

In gix_path::env, the underlying implementation of the installation_config and installation_config_prefix functions calls git config -l --show-origin to find the path of a file to treat as belonging to the git installation.

Affected versions of gix-path do not pass -z/--null to cause git to report literal paths (650a1b5). Instead, to cover the occasional case that git outputs a quoted path, they attempt to parse the path by stripping the quotation marks:

https://github.com/Byron/gitoxide/blob/1cfe577d461293879e91538dbc4bbfe01722e1e8/gix-path/src/env/git/mod.rs#L138-L142

The problem is that, when a path is quoted, it may change in substantial ways beyond the concatenation of quotation marks. If not reversed, these changes can result in another valid path that is not equivalent to the original.

This is not limited to paths with unusual characters such as quotation marks or newlines. Unless git is explicitly configured with core.quotePath set to false, it also happens when the path contains most non-ASCII characters, including accented or non-English letters. For example, é is transformed to \303\251, with literal backslashes. (This is an octal representation of the bytes in its UTF-8 encoding. This behavior is not limited to systems that encode paths with UTF-8 on disk.)

Rarely, the configuration file gix-path wrongly attempts to open can be created by an attacker who has a limited user account on the system. The attacker would often need to request an account username tailored to carrying out the attack.

PoC

Quick demonstration on Unix

On a Unix-like system in which Git supports no higher scope than system for configuration variables (i.e., not on macOS with Apple Git), in a locale that supports UTF-8, with gitoxide installed, run:

mkdir myrepo
cd myrepo
git init
printf '[real]\n\trealvar = realval\n' > 'é'
printf '[fake]\n\tfakevar = fakeval\n' > '\303\251'
GIT_CONFIG_SYSTEM='é' gix config

If the above conditions are satisfied and the gix command was built against an affected version of gix-path, then the last command's output looks something like this:

# From '\303\251' (GitInstallation)
[fake]
        fakevar = fakeval

# From 'é' (System)
[real]
        realvar = realval

# From '/home/ubuntu/.gitconfig' (User)
[init]
        defaultBranch = main

# From './.git/config' (Local)
[core]
        repositoryformatversion = 0
        filemode = true
        bare = false
        logallrefupdates = true

Demonstration across user accounts on Windows

On a test system running Windows on which Git for Windows is not installed system-wide—resembling a scenario in which users who wish to use Git are expected to install it themselves for their accounts—create two accounts, with these usernames:

• Renée, the target of the attack. This user may be a limited user or an administrator. Its user profile directory is assumed to be C:\Users\Renée.
• Ren, the user who carries out the attack. This user should be a limited user, since an administrator would not need to exploit this vulnerability to inject configuration. Its user profile directory is assumed to be C:\Users\Ren.

As Ren, run these commands in PowerShell:

$d = "$HOME\303\251e\AppData\Local\Programs\Git\etc"
mkdir $d
git config --file $d\gitconfig core.sshCommand calc.exe
icacls $HOME\303 /grant 'Renée:(RX)' /T

(The gitconfig file can instead be written manually, in which case Ren need not have git.)

As Renée:

1. Install Git for Windows in the default location for…

gix-path is a crate of the gitoxide project (an implementation of git written in Rust) dealing paths and their conversions. Prior to version 0.10.11, gix-path runs git to find the path of a configuration file associated with the git installation, but improperly resolves paths containing unusual or non-ASCII characters, in rare cases enabling a local attacker to inject configuration leading to code execution. Version 0.10.11 contains a patch for the issue.

In gix_path::env, the underlying implementation of the installation_config and installation_config_prefix functions calls git config -l --show-origin to find the path of a file to treat as belonging to the git installation. Affected versions of gix-path do not pass -z/--null to cause git to report literal paths. Instead, to cover the occasional case that git outputs a quoted path, they attempt to parse the path by stripping the quotation marks. The problem is that, when a path is quoted, it may change in substantial ways beyond the concatenation of quotation marks. If not reversed, these changes can result in another valid path that is not equivalent to the original.

On a single-user system, it is not possible to exploit this, unless GIT_CONFIG_SYSTEM and GIT_CONFIG_GLOBAL have been set to unusual values or Git has been installed in an unusual way. Such a scenario is not expected. Exploitation is unlikely even on a multi-user system, though it is plausible in some uncommon configurations or use cases. In general, exploitation is more likely to succeed if users are expected to install git themselves, and are likely to do so in predictable locations; locations where git is installed, whether due to usernames in their paths or otherwise, contain characters that git quotes by default in paths, such as non-English letters and accented letters; a custom system-scope configuration file is specified with the GIT_CONFIG_SYSTEM environment variable, and its path is in an unusual location or has strangely named components; or a system-scope configuration file is absent, empty, or suppressed by means other than GIT_CONFIG_NOSYSTEM. Currently, gix-path can treat a global-scope configuration file as belonging to the installation if no higher scope configuration file is available. This increases the likelihood of exploitation even on a system where git is installed system-wide in an ordinary way. However, exploitation is expected to be very difficult even under any combination of those factors.

gix-path is a crate of the gitoxide project (an implementation of git written in Rust) dealing paths and their conversions. Prior to version 0.10.11, gix-path runs git to find the path of a configuration file associated with the git installation, but improperly resolves paths containing unusual or non-ASCII characters, in rare cases enabling a local attacker to inject configuration leading to code execution. Version 0.10.11 contains a patch for the issue.

In gix_path::env, the underlying implementation of the installation_config and installation_config_prefix functions calls git config -l --show-origin to find the path of a file to treat as belonging to the git installation. Affected versions of gix-path do not pass -z/--null to cause git to report literal paths. Instead, to cover the occasional case that git outputs a quoted path, they attempt to parse the path by stripping the quotation marks. The problem is that, when a path is quoted, it may change in substantial ways beyond the concatenation of quotation marks. If not reversed, these changes can result in another valid path that is not equivalent to the original.

On a single-user system, it is not possible to exploit this, unless GIT_CONFIG_SYSTEM and GIT_CONFIG_GLOBAL have been set to unusual values or Git has been installed in an unusual way. Such a scenario is not expected. Exploitation is unlikely even on a multi-user system, though it is plausible in some uncommon configurations or use cases. In general, exploitation is more likely to succeed if users are expected to install git themselves, and are likely to do so in predictable locations; locations where git is installed, whether due to usernames in their paths or otherwise, contain characters that git quotes by default in paths, such as non-English letters and accented letters; a custom system-scope configuration file is specified with the GIT_CONFIG_SYSTEM environment variable, and its path is in an unusual location or has strangely named components; or a system-scope configuration file is absent, empty, or suppressed by means other than GIT_CONFIG_NOSYSTEM. Currently, gix-path can treat a global-scope configuration file as belonging to the installation if no higher scope configuration file is available. This increases the likelihood of exploitation even on a system where git is installed system-wide in an ordinary way. However, exploitation is expected to be very difficult even under any combination of those factors.

gix-path is a crate of the gitoxide project (an implementation of git written in Rust) dealing paths and their conversions. Prior to version 0.10.11, gix-path runs git to find the path of a configuration file associated with the git installation, but improperly resolves paths containing unusual or non-ASCII characters, in rare cases enabling a local attacker to inject configuration leading to code execution. Version 0.10.11 contains a patch for the issue. In gix_path::env, the underlying implementation of the installation_config and installation_config_prefix functions calls git config -l --show-origin to find the path of a file to treat as belonging to the git installation. Affected versions of gix-path do not pass -z/--null to cause git to report literal paths. Instead, to cover the occasional case that git outputs a quoted path, they attempt to parse the path by stripping the quotation marks. The problem is that, when a path is quoted, it may change in substantial ways beyond the concatenation of quotation marks. If not reversed, these changes can result in another valid path that is not equivalent to the original. On a single-user system, it is not possible to exploit this, unless GIT_CONFIG_SYSTEM and GIT_CONFIG_GLOBAL have been set to unusual values or Git has been installed in an unusual way. Such a scenario is not expected. Exploitation is unlikely even on a multi-user system, though it is plausible in some uncommon configurations or use cases. In general, exploitation is more likely to succeed if users are expected to install git themselves, and are likely to do so in predictable locations; locations where git is installed, whether due to usernames in their paths or otherwise, contain characters that git quotes by default in paths, such as non-English letters and accented letters; a custom system-scope configuration file is specified with the GIT_CONFIG_SYSTEM environment variable, and its path is in an unusual location or has strangely named components; or a system-scope configuration file is absent, empty, or suppressed by means other than GIT_CONFIG_NOSYSTEM. Currently, gix-path can treat a global-scope configuration file as belonging to the installation if no higher scope configuration file is available. This increases the likelihood of exploitation even on a system where git is installed system-wide in an ordinary way. However, exploitation is expected to be very difficult even under any combination of those factors.