# [HIGH] Log4j 2.16 High Severity Vulnerability (CVE-2021-45105) Discovered

**Source:** Snyk
**Published:** 2021-12-18
**Article:** https://snyk.io/blog/log4j-2-16-vulnerability-cve-2021-45105-discovered/

## Threat Profile

Snyk Blog In this article
Written by Jason Lane 
Benji Catabi-Kalman 
December 18, 2021
0 mins read Overnight, it was disclosed by Apache that Log4j version 2.16 is also vulnerable by way of a Denial of Service attack with the impact being a full application crash , the severity for this is classified as High (7.5) . Snyk is currently not aware of any fully-fledged PoCs or exploits in circulation. CVE-2021-45105 has been issued, and a new fixed version ( 2.17.1 ) has been published by Apache whi…

## Indicators of Compromise (high-fidelity only)

- **CVE:** `CVE-2021-45105`
- **CVE:** `CVE-2021-44228`

## MITRE ATT&CK Techniques

- **T1190** — Exploit Public-Facing Application
- **T1195.002** — Compromise Software Supply Chain

## Kill chain phases observed

_(none detected from narrative keywords)_

## Recommended hunts

### Trusted vendor binary / installer launching unusual children

`UC_SUPPLY_CHAIN` · phase: **exploit** · confidence: **Medium**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime
    from datamodel=Endpoint.Processes
    where Processes.parent_process_name IN ("setup.exe","installer.exe","update.exe")
      AND Processes.process_name IN ("powershell.exe","cmd.exe","rundll32.exe","regsvr32.exe","mshta.exe","wscript.exe","cscript.exe","wmic.exe","bitsadmin.exe")
    by Processes.dest, Processes.user, Processes.parent_process_name, Processes.process_name, Processes.process
| `drop_dm_object_name(Processes)`
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(7d)
| where AccountName !endswith "$"
| where InitiatingProcessFileName in~ ("setup.exe","installer.exe","update.exe")
| where FileName in~ ("powershell.exe","cmd.exe","rundll32.exe","regsvr32.exe","mshta.exe","wscript.exe","cscript.exe","wmic.exe","bitsadmin.exe")
| project Timestamp, DeviceName, AccountName, InitiatingProcessFileName, FileName, ProcessCommandLine
```

### IOC-driven hunts (use shared templates)

These are standard IOC-substitution hunts — the canonical SPL and KQL live once in [`_TEMPLATES.md`](../_TEMPLATES.md), so we don't repeat the same boilerplate on every CVE / hash / network-IOC briefing.

- **Asset exposure — vulnerability matches article CVE(s)** ([template](../_TEMPLATES.md#asset-exposure)) — phase: **recon**, confidence: **High**
  - CVE(s): `CVE-2021-45105`, `CVE-2021-44228`


## Why this matters

Severity classified as **HIGH** based on: CVE present, 2 use case(s) fired, 2 technique(s) inferred. Read the full article for actor attribution, tooling details, and any defanged IOCs in the body that aren't visible in the RSS summary.