CVE-2021-44228

Apache Log4j2: Remote Code Execution

As of , CVE-2021-44228 in Apache Log4j2 is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch this week.

Exploited
Yes: CISA listed it on 10 December 2021
US federal deadline
24 December 202114 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
Known
EPSS score
0.99Higher than 99% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
EPSS when listed
Not availableCISA listed it before 4 February 2022, where the EPSS files we read begin.
Public exploit
5 Metasploit modules and 3 Exploit-DB entries
Fix
No vendor link in CISA's entry

What CISA says to do

For all affected software assets for which updates exist, the only acceptable remediation actions are: 1) Apply updates; OR 2) remove affected assets from agency networks. Temporary mitigations using one of the measures provided at https://www.cisa.gov/uscert/ed-22-02-apache-log4j-recommended-mitigation-measures are only acceptable until updates are available.

CISA's required action

What the flaw is

Apache Log4j2 contains a vulnerability where JNDI features do not protect against attacker-controlled JNDI-related endpoints, allowing for remote code execution.

CISA's description

Apache Log4j2 2.0-beta9 through 2.15.0 (excluding security releases 2.12.2, 2.12.3, and 2.3.1) JNDI features used in configuration, log messages, and parameters do not protect against attacker controlled LDAP and other JNDI related endpoints. An attacker who can control log messages or log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled. From log4j 2.15.0, this behavior has been disabled by default. From version 2.16.0 (along with 2.12.2, 2.12.3, and 2.3.1), this functionality has been completely removed. Note that this vulnerability is specific to log4j-core and does not affect log4net, log4cxx, or other Apache Logging Services projects.

The CVE record's description, from apache

CVE published
10 December 2021
Assigned by
apache
CVSS
10.0 Critical (CVSS 3.1, from CISA-ADP)
CWE-502
Deserialization of Untrusted Data
CWE-400
Uncontrolled Resource Consumption
CWE-20
Improper Input Validation
CISA SSVC, exploitation
active
CISA SSVC, automatable
yes
CISA SSVC, technical impact
total

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. Exploit-DB published an exploit (EDB-ID 50590).
  4. Exploit-DB published an exploit (EDB-ID 50592).
  5. The US federal deadline to fix it.
  6. Exploit-DB published an exploit (EDB-ID 51183).

Public exploits

Facts from Metasploit's module list and Exploit-DB's index; we never copy exploit code.

  • Metasploit: MobileIron Core Unauthenticated JNDI Injection RCE (via Log4Shell)exploit module, rank excellent
  • Metasploit: Log4Shell HTTP Header Injectionexploit module, rank excellent
  • Metasploit: UniFi Network Application Unauthenticated JNDI Injection RCE (via Log4Shell)exploit module, rank excellent
  • Metasploit: VMware vCenter Server Unauthenticated JNDI Injection RCE (via Log4Shell)exploit module, rank excellent
  • Metasploit: Log4Shell HTTP Scannerauxiliary module, rank normal
  • Exploit-DB: AD Manager Plus 7122 - Remote Code Execution (RCE)EDB-ID 51183, 1 April 2023
  • Exploit-DB: Apache Log4j2 2.14.1 - Information DisclosureEDB-ID 50590, 14 December 2021
  • Exploit-DB: Apache Log4j 2 - Remote Code Execution (RCE)EDB-ID 50592, 14 December 2021

Log4j2: other exploited entries

VulnerabilityProductOur groupListedDeadlineEPSS
CVE-2021-45046Deserialization of Untrusted DataApache Log4j2Patch this weekRansomware use; Metasploit module; EPSS 0.990.99

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