CVERadar
CRITICAL · CVSS 3.1 10CISA KEV · added 2021-12-10Metasploit moduleExploit-DBPublic PoCKnown ransomware useEPSS 100.00% (p100)Threat level 100

CVE-2021-44228: Apache Log4j2 Remote Code Execution Vulnerability

Apache · Log4j2 · NVD published 2021-12-10 · posted 2026-10-21 · last modified 2026-08-12

What it is

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.

WeaknessCWE-20CWE-400CWE-502CWE-917
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H (source: [email protected])
CISA due date2021-12-24 (for US federal agencies under BOD; a good deadline for everyone)
ATT&CK tacticsResource Development → Initial Access → Persistence → Impact

Exploitation evidence

First exploit evidence seen: 2021-12-09 (earliest date across the sources below).

Exploited in the wild

  • CISA KEV: listed since 2021-12-10. Source

Public exploit code

Metasploit

Exploit-DB

  • EDB-50592: Apache Log4j 2 - Remote Code Execution (RCE) (2021-12-14)
  • EDB-50590: Apache Log4j2 2.14.1 - Information Disclosure (2021-12-14)
  • EDB-51183: AD Manager Plus 7122 - Remote Code Execution (RCE) (2023-04-01)

GitHub proof-of-concept repositories

469 public repositories from 444 accounts, first seen 2021-12-10. Most starred: fullhunt/log4j-scan (3425 stars), view repository.

Verify before running: public PoCs can be malicious. Read the code and only run it in an isolated lab. A PoC means exploit code is public, not that this CVE is exploited in the wild.

Sources: CISA KEV · Rapid7 Metasploit Framework module metadata · Exploit-DB (OffSec) · nomi-sec/PoC-in-GitHub.

Defend the Chain

The attack chain for CVE-2021-44228 laid across the MITRE ATT&CK Enterprise tactics. Solid cards come from the MITRE CTID KEV mappings; dashed cards are inferred by CVERadar from the CWE or description. Correct defences are real ATT&CK mitigations for that technique.

Threat level 100/100
Defender level 1 · 0 XP
Chain links broken: 0/5

Reconnaissance

Resource Development

Initial Access

Execution

Persistence

Privilege Escalation

Stealth

Defense Impairment

Credential Access

Discovery

Lateral Movement

Collection

Command and Control

Exfiltration

Impact

Pick a red technique card on the board, then choose the defence that stops it.

Defend against T1608.001 Upload Malware CTID: secondary impact

CVE-2021-44228, known as Log4Shell, affects Apache’s Log4j library, an open-source logging framework. An actor can exploit this vulnerability by submitting a specially crafted request to a vulnerable system that causes that system to execute arbitrary code. The request allows a cyber actor to take full control over the system. The actor can then steal information, launch ransomware, or conduct other malicious activity.

How to fix it

CISA required action

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. (source: CISA KEV)

Fixed versions

  • siemens 6bk1602-0aa12-0tp0 firmware: upgrade to 2.7.0 or later
  • siemens 6bk1602-0aa22-0tp0 firmware: upgrade to 2.7.0 or later
  • siemens 6bk1602-0aa32-0tp0 firmware: upgrade to 2.7.0 or later
  • siemens 6bk1602-0aa42-0tp0 firmware: upgrade to 2.7.0 or later
  • siemens 6bk1602-0aa52-0tp0 firmware: upgrade to 2.7.0 or later
  • apache log4j: upgrade to 2.3.1 or later (affected from 2.0.1)
  • apache log4j: upgrade to 2.12.2 or later (affected from 2.4.0)
  • apache log4j: upgrade to 2.15.0 or later (affected from 2.13.0)
  • siemens capital: upgrade to 2019.1 or later
  • siemens comos: upgrade to 10.4.2 or later
  • siemens e-car operation center: upgrade to 2021-12-13 or later
  • siemens energyip prepay: upgrade to 3.8.0.12 or later
  • siemens gma-manager: upgrade to 8.6.2j-398 or later
  • siemens industrial edge management hub: upgrade to 2021-12-13 or later
  • siemens mindsphere: upgrade to 2021-12-16 or later
  • siemens navigator: upgrade to 2021-12-13 or later
  • siemens opcenter intelligence: upgrade to 3.5 or later (affected from 3.2)
  • siemens siguard dsa: upgrade to 4.4.1 or later (affected from 4.2)
  • siemens solid edge harness design: upgrade to 2020 or later
  • siemens spectrum power 4: upgrade to 4.70 or later
  • siemens spectrum power 7: upgrade to 2.30 or later
  • siemens vesys: upgrade to 2019.1 or later
  • intel datacenter manager: upgrade to 5.1 or later

Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.

Vendor advisories and patches

MITRE ATT&CK mitigations for this chain

  • M1056 Pre-compromise (for T1608.001) : This technique cannot be easily mitigated with preventive controls since it is based on behaviors performed outside of the scope of enterprise defenses and controls.
  • M1048 Application Isolation and Sandboxing (for T1190) : Application isolation will limit what other processes and system features the exploited target can access.
  • M1037 Filter Network Traffic (for T1190) : Restrict outbound network traffic from public-facing servers to prevent unauthorized connections from initiating communications with attacker-controlled infrastructure. While this may not prevent the initial exploitation, it limits the attacker's ability to verify and control the compromised server post-exploit, reduci
  • M1030 Network Segmentation (for T1190) : Segment externally facing servers and services from the rest of the network with a DMZ or on separate hosting infrastructure.
  • M1016 Vulnerability Scanning (for T1190) : Regularly scan externally facing systems for vulnerabilities and establish procedures to rapidly patch systems when critical vulnerabilities are discovered through scanning and through public disclosure.
  • M1026 Privileged Account Management (for T1190) : Use least privilege for service accounts will limit what permissions the exploited process gets on the rest of the system.
  • M1050 Exploit Protection (for T1190) : Web Application Firewalls may be used to limit exposure of applications to prevent exploit traffic from reaching the application.
  • M1035 Limit Access to Resource Over Network (for T1190) : Ensure that all publicly exposed services are actually intended to be so, and restrict access to any that should only be available internally.
  • M1051 Update Software (for T1190) : Update software regularly by employing patch management for externally exposed applications.
  • M1042 Disable or Remove Feature or Program (for T1505.003) : Consider disabling functions from web technologies such as PHP’s `evaI()` that may be abused for web shells.

Detection Generic guidance

  • Initial Access: Alert on unusual requests to the affected service (odd paths, oversized payloads, exploit strings) in WAF, reverse-proxy and application logs.
  • Persistence: Look for new files in web roots, new scheduled tasks/services, and new accounts created after the exposure window.
  • Impact: Monitor service availability, unexpected encryption activity and mass file changes.

Response checklist Generic guidance

  1. Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
  2. Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
  3. Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
  4. Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.

Sources