How to use MFA with AWS CLI? - amazon-web-services

Question

How do I type in the MFA code when using the AWS CLI? I have checked the documentation page of IAM http://docs.aws.amazon.com/cli/latest/reference/iam/index.html.
I have the MFA-Devices already enabled under my username.
aws iam list-mfa-devices --user-name X
returns
{
"MFADevices": [
{
"UserName": "X",
"SerialNumber": "arn:aws:iam::+++:mfa/X",
"EnableDate": "2016-01-13T23:15:43Z"
}
]
}

Answer 1

The CLI can manage a lot of this for you if you're using roles. Described here: http://docs.aws.amazon.com/cli/latest/userguide/cli-roles.html
In my credentials file I have:
[my_iam_user]
aws_access_key_id = AKIABLAHBLAHBLAHBLAH
aws_secret_access_key = <blah>
region = us-east-1
[my_admin_role]
role_arn = arn:aws:iam::123456789123:role/my_admin_role
source_profile = my_iam_user
mfa_serial = arn:aws:iam::123456789123:mfa/my_iam_user
region = us-east-1
Note the mfa_serial entry. You can get this value from your user details in the AWS IAM console. This entry tells the CLI that MFA is required for that role.
When I call aws s3 ls --profile my_admin_role it says Enter MFA code:, after I paste in the code it returns the listing.
Note: I haven't found a way to get the CLI to ask for MFA when calling a user profile (--profile my_iam_user) only calling a role profile triggers the MFA request.
The MFA token is then carried forward and the user profile can be used as well:
aws sts get-caller-identity --profile my_iam_user
# {
# "Account": "123456789123",
# "UserId": "AIDABLAHBLAHBLAHBLAH",
# "Arn": "arn:aws:iam::123456789123:user/my_iam_user"
# }
aws sts get-caller-identity --profile my_admin_role
# {
# "Account": "123456789123",
# "UserId": "AROABLAHBLAHBLAHBLAH:AWS-CLI-session-1234567890",
# "Arn": "arn:aws:sts::123456789123:assumed-role/my_admin_role/AWS-CLI-session-1234567890"
# }

Answer 2

Call aws sts get-session-token --serial-number <serial> --token-code <code> documented here. This will give you a temporary security token. Documentation on using the temporary security token can be found here.

Answer 3

Step-by-step manual solution:
Request a session token with MFA
aws sts get-session-token --serial-number arn-of-the-mfa-device --token-code code-from-token
arn-of-the-mfa-device: visible from your user IAM
Option: Use CLI to retrieve: aws iam list-mfa-devices --user-name ryan
Option: View in IAM console: IAM --> Users --> --> Security Credentials
code-from-token: 6 digit code from your configured MFA device
Create a profile with the returned credentials
aws configure --profile cli
aws configure set --profile cli aws_session_token <SESSION_TOKEN_HERE>
aws_session_token is not included in aws configure
Test command
aws s3 ls --profile cli

Answer 4

I have published a PR for aws-cli, which will allow to use mfa_serial in the credentials, that will force you to enter the token before making request to AWS (and it will be cached while token is valid)
Issue: https://github.com/aws/aws-cli/issues/3172
botocore PR: https://github.com/boto/botocore/pull/1399
aws-cli PR: https://github.com/aws/aws-cli/pull/3174
Feel free to vote, if you want to get it in.

Answer 5

aws-mfa acts as a wrapper around sts and works really well: https://github.com/broamski/aws-mfa

Answer 6

Wrote a tool to add MFA support for standard IAM user profiles until #outcoldman PR gets merged: https://github.com/tongueroo/aws-mfa-secure
Setup for those in a hurry
Install gem
gem install aws-mfa-secure
Setup your ~/.aws/credentials with mfa_serial
~/.aws/credentials:
[mfa]
aws_access_key_id = BKCAXZ6ODJLQ1EXAMPLE
aws_secret_access_key = ABCDl4hXikfOHTvNqFAnb2Ea62bUuu/eUEXAMPLE
mfa_serial = arn:aws:iam::112233445566:mfa/MFAUser
Add the alias to your ~/.bash_profile
alias aws="aws-mfa-secure session"
Restart your terminal.
Example with Output
$ export AWS_PROFILE=mfa
$ aws s3 ls
Please provide your MFA code: 751888
2019-09-21 15:53:34 my-example-test-bucket
$ aws s3 ls
2019-09-21 15:53:34 my-example-test-bucket
$
Assume Role Profiles
Assume role profiles work already for the AWS CLI, here's an example:
~/.aws/credentials:
[mfa]
aws_access_key_id = BKCAXZ6ODJLQ1EXAMPLE
aws_secret_access_key = ABCDl4hXikfOHTvNqFAnb2Ea62bUuu/eUEXAMPLE
mfa_serial = arn:aws:iam::112233445566:mfa/MFAUser
[assumed-role]
role_arn = arn:aws:iam::112233445566:role/Admin
source_profile = mfa
role_session_name = MFAUser
mfa_serial = arn:aws:iam::112233445566:mfa/MFAUser

Answer 7

On Windows
I'm on windows and I created a batch file to pass in my MFA code and have it automatically set up my credentials. First, you need to set up your production credentials in AWS:
aws configure --profile prod
Answer the questions appropriately with your key and secret. Then, I run my script like this:
C:\> mfa-getCreds.bat 229168
Your credentials are set up, and will expire on 2019-05-12T04:04:13Z
Now you should be able to run aws commands like this: aws s3 ls
Here are the contents of my mfa-getCreds.bat:
#echo off
set TOKEN=%1
if not defined TOKEN goto showUsage
#call aws sts get-session-token --profile prod --serial-number "arn:aws:iam::109627855994:mfa/ryan.shillington" --token-code %* > c:\temp\mfa-getCreds.json
FOR /F "tokens=* USEBACKQ" %%g IN (`jq -r ".Credentials.AccessKeyId" c:\temp\mfa-getCreds.json`) do (SET AWS_ACCESS_KEY=%%g)
FOR /F "tokens=*" %%g IN ('jq -r ".Credentials.SecretAccessKey" c:\temp\mfa-getCreds.json') do (SET "AWS_SECRET_KEY=%%g")
FOR /F "tokens=*" %%g IN ('jq -r ".Credentials.SessionToken" c:\temp\mfa-getCreds.json') do (SET "AWS_SESSION_TOKEN=%%g")
FOR /F "tokens=*" %%g IN ('jq -r ".Credentials.Expiration" c:\temp\mfa-getCreds.json') do (SET "EXPIRATION=%%g")
set AWS_ACCESS_KEY_ID=%AWS_ACCESS_KEY%
set "AWS_SECRET_ACCESS_KEY=%AWS_SECRET_KEY%"
echo.
echo Your credentials are set up, but will expire on %EXPIRATION%
echo.
echo Now you should be able to run aws commands like this: aws s3 ls
goto :EOF
:showUsage
echo Usage: %0 [MFA Token]
goto :EOF
For this to run, you'll need the excellent jq package in your path.

Answer 8

My use-case is I have a root account where all IAM users are created and assigned to IAM groups which in turn have the capability to assume roles on a different account with varying degree of access depending on the group they are on. I have a few house rules in place;
No one is allowed to do anything on the root account except to manage their own IAM Users account.
Required password reset.
Required MFA.
You cannot switch accounts without logging in with MFA.
This has been set up using AWS Shared Organizations.
Previously, I've been using a python script I wrote to let my users to login via cli with MFA and switch accounts. This is done by manipulating the ~/.aws/credentials.
I've since migrated to using this project https://gitlab.com/severity1/aws-auth, which is written in Go and allows me to do the same without much setup and it works on windows, macosx and linux.
This effectively gives all my users the ability to do local testing while developing Apps for AWS without having to hardcode AWS Credentials into their code.

Answer 9

Run the sts get-session-token AWS CLI command, replacing the variables with information from your account, resources, and MFA device:
$ aws sts get-session-token --serial-number arn-of-the-mfa-device --token-code code-from-token
https://aws.amazon.com/premiumsupport/knowledge-center/authenticate-mfa-cli/

Answer 10

I wrote a small bash script to get over this annoying problem.
You can find it here: https://gist.github.com/geekgunda/db4c9c8d850c08a48d1d60f119628032
Assumptions:
Your original AWS Creds should be stored at ~/.aws/credentials
You've corrected ARN for MFA device (search for FIXME)
You've given correct MFA Code as cli argument
You have jq installed. Ref: https://stedolan.github.io/jq/

Answer 11

We documented a few considerations for AWS API multifactor in general (where to add the conditions, what are the implications etc.) in the documentation for some custom tooling (https://github.com/kreuzwerker/awsu) we developed for using Yubikeys as source for the TOTP tokens. This makes working with roles and long-term credentials + session tokens pretty easy.

Answer 12

I have forked Chinmay's gist and updated it to pull the device serial from aws instead of hardcoding it. I have also updated the exits to return a status of 1 instead of just exiting.
Available here:
https://gist.github.com/jpribyl/e44021ae5cbf7fd1b4549598e85b5341
I am using it in deploy scripts like this (I renamed the script to awsMfaCli.sh):
. awsMfaCli.sh
script_status=$?
if [[ $script_status -ne 1 ]]; then
echo "Building production"
if npm run build ; then
echo "Build Successful"
else
echo "Error building, exiting.."
return 1
fi
echo "Removing all files on bucket.."
aws s3 rm --recursive s3://mybucket
echo "Uploading site.."
aws s3 sync build/ s3://mybucket
echo "S3 Upload complete.."
echo "Deployment complete."
else
return 1
fi

Answer 13

AWS MFA use on the command line can be rather unpleasant and cumbersome, especially if you have multiple profiles and roles.
I have released awscli-mfa.sh script that makes MFA/role session management on the command line a lot easier. A companion script enable-disable-vmfa-device.sh similarly makes it easy to enable or disable a virtual MFA device on an IAM user account.
awscli-mfa.sh persists a started session in ~/.aws/credentials (with some info in ~/.aws/config), or allows you to start an in-env session only so that its details don't get persisted. When executed in Windows Subsystem for Linux, the script also provides session activation strings for PowerShell and Windows command line. However, the script itself only runs in bash (written for macOS, Linux, and WSL bash with Ubuntu).
You can find the scripts and the example MFA policies in my GitHub repo at https://github.com/vwal/awscli-mfa

Answer 14

A one-liner to authorize and append an MFA user to your credentials file using jq:
SERIAL_NUMBER=arn:aws:iam::000000000000:mfa/john TOKEN_CODE=123123 PROFILE_NAME=my_aws_2fa; \
aws sts get-session-token --serial-number $SERIAL_NUMBER --token-code $TOKEN_CODE \
| jq -r '.Credentials | ("aws_access_key_id = " + .AccessKeyId), ("aws_secret_access_key = " + .SecretAccessKey), ("aws_session_token = " + .SessionToken)' \
| (echo "\n[$PROFILE_NAME]" && cat) >> ~/.aws/credentials

Answer 15

Summary
Authenticating with MFA is done with the aws sts command. The basic process is:
Set up a "permanent" profile in ~/.aws/credentials.
Call the aws sts command with the "permanent" profile.
Create a "temporary" profile in ~/.aws/credentials with the result from #2
Use the "temporary" profile with your aws commands.
Details
#1:
[myaccountPerm]
aws_access_key_id = REDACTED
aws_secret_access_key = REDACTED
#2:
$ aws sts get-session-token --token-code 123456 --profile myaccountPerm --serial-number arn:aws:iam::REDACTED:mfa/REDACTED
{
"Credentials": {
"AccessKeyId": "REDACTED",
"SecretAccessKey": "REDACTED",
"SessionToken": "REDACTED",
"Expiration": "2021-03-13T09:37:10Z"
}
}
#3:
[myaccount]
aws_access_key_id = REDACTED
aws_secret_access_key = REDACTED
aws_session_token = REDACTED
Solution
You'll notice that this is kind of an excessive process for logging in. I recommend using a utility/script for this purpose. Several exist, including some mentioned in other answers.
I have also written such a utility, as well as an in-depth article on how to authenticate with MFA using the AWS CLI (includes a couple of other details, like how to require MFA).
My utility is just a short script, and doesn't use a pip installer, which makes it easy to inspect.
Overview of process
Utility for automation

Answer 16

I think my answer will be useful for people trying to follow the official docs, which sadly leave out a lot of details. I discovered a few nuances when trying to figure out how to do this according to the official docs so I wrote this up to help.
I originally had a non-MFA CLI user configured in my ~/.aws/credentials file
(this will be important later)
I then created a 2nd user "mfa-test" to which I attached a custom policy named Force_MFA. I sourced the policy from this aws doc
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "AllowListActions",
"Effect": "Allow",
"Action": [
"iam:ListUsers",
"iam:ListVirtualMFADevices"
],
"Resource": "*"
},
{
"Sid": "AllowIndividualUserToManageTheirOwnMFA",
"Effect": "Allow",
"Action": [
"iam:CreateVirtualMFADevice",
"iam:DeleteVirtualMFADevice",
"iam:ListMFADevices",
"iam:EnableMFADevice",
"iam:ResyncMFADevice"
],
"Resource": [
"arn:aws:iam::*:mfa/${aws:username}",
"arn:aws:iam::*:user/${aws:username}"
]
},
{
"Sid": "AllowIndividualUserToDeactivateOnlyTheirOwnMFAOnlyWhenUsingMFA",
"Effect": "Allow",
"Action": [
"iam:DeactivateMFADevice"
],
"Resource": [
"arn:aws:iam::*:mfa/${aws:username}",
"arn:aws:iam::*:user/${aws:username}"
],
"Condition": {
"Bool": {
"aws:MultiFactorAuthPresent": "true"
}
}
},
{
"Sid": "BlockMostAccessUnlessSignedInWithMFA",
"Effect": "Deny",
"NotAction": [
"iam:CreateVirtualMFADevice",
"iam:EnableMFADevice",
"iam:ListMFADevices",
"iam:ListUsers",
"iam:ListVirtualMFADevices",
"iam:ResyncMFADevice"
],
"Resource": "*",
"Condition": {
"BoolIfExists": {
"aws:MultiFactorAuthPresent": "false"
}
}
}
]
}
Nuances I learned about this command:
aws sts get-session-token --serial-number arn:aws:iam::853680132675:mfa/mfa-test --token-code 630011
You should update to the latest version of the AWS CLI before running the command.
The docs mention it might fail if your aws cli isn't updated, but it's easy to miss that suggestion.
The TOTP(time-based one-time password) token code 630011 comes from your virtual MFA device
arn:aws:iam::853680132675:mfa/mfa-test can be looked up by viewing the Security credentials tab of the IAM user.
The command will fail (without a useful error message) if ~/.aws/credentials corresponds to another account (like non-MFA CLI user).
[default]
aws_access_key_id = lalala
aws_secret_access_key = lalala
In other words, there's a hard requirement that the credentials used when running the aws sts get-session-token --serial-number arn:aws:iam::853680132675:mfa/mfa-test --token-code 630011 command, map to the user referenced in that command (username = mfa-test). (The only exception is if you have additional profiles defined in ~/.aws/credentials & ~/.aws/config and reference them
using --profile additional_profile)
So I'd recommend running aws sts get-caller-identity and making sure you see the user (mfa-test) in the results (.../user/mfa-test) matches the user mentioned in the ARN of the mfa device (.../mfa/mfa-test)
"Arn": "arn:aws:iam::853680132675:user/mfa-test"
Also if you install jq (json query) cli tool then unix users can use the following trick to streamline the trade-off of non-MFA CLI creds to MFA CLI creds that expire after 12 hours by default (note the | tr -d '"' in the command is read as translate delete ", it strips out the double quotes)
export MFA_CLI_SESSION=$(aws sts get-session-token --serial-number arn:aws:iam::853680132675:mfa/mfa-test --token-code 630011)
export AWS_ACCESS_KEY_ID=$( echo $MFA_CLI_SESSION | jq .Credentials.AccessKeyId | tr -d '"' )
export AWS_SECRET_ACCESS_KEY=$( echo $MFA_CLI_SESSION | jq .Credentials.SecretAccessKey | tr -d '"' )
export AWS_SESSION_TOKEN=$( echo $MFA_CLI_SESSION | jq .Credentials.SessionToken | tr -d '"' )
You can run these commands as a smoke test to verify the variables aren't empty.
echo $MFA_CLI_SESSION
echo $AWS_ACCESS_KEY_ID
echo $AWS_SECRET_ACCESS_KEY
echo $AWS_SESSION_TOKEN
From this point on your AWS CLI commands will work for the next 12 hours within that terminal session (since they're implemented as env vars). Also they'll work without having to add --profile additional_profile flag to your commands.

Answer 17

Snippet easy to copy and paste.
cat <<EOF >aws-credentials.sh
export AWS_ACCESS_KEY_ID=<key>
export AWS_SECRET_ACCESS_KEY=<secret>
export AWS_DEFAULT_REGION=us-east-1
export AWS_USER=<aws_user>
export AWS_ACCOUNT=<aws_account>
EOF
# Almost one liner:
source aws-credentials.sh
source <(paste -d= <(echo -ne "export AWS_ACCESS_KEY_ID\nexport AWS_SECRET_ACCESS_KEY\nexport AWS_SESSION_TOKEN\nexport EXPIRATION\n") <(aws sts get-session-token --duration-seconds 129600 --serial-number arn:aws:iam::$AWS_ACCOUNT:mfa/$AWS_USER --token-code $(read -p "Token:" TOKEN; echo $TOKEN) | jq '.Credentials | .[]'))
# Example
aws s3 ls s3://my-bucket/