Presentation of the security principles in WAPT¶
Here are documented the advanced security principles included in WAPT.
The reading of this portion of the documentation is not essential for your daily usage of WAPT; it is however recommended for you to better understand some architectural choices made by the developers of the software.
Preamble and definitions¶
Attention
The WAPT service operates as a privileged system account.
Attention
From WAPT version 1.5, the default installation directory becomes
C:\Program Files (x86)\wapt.
Hint
the sub-components wapttray, waptservice and waptexit of the WAPT agent may be optionally deactivated according to usage context.
Perimeter to secure¶
The elements to secure and that strictly concern WAPT are:
The WAPT Server (waptserver).
The WAPT agents (wapt-get) and its sub-components (wapttray, waptservice et waptexit).
The management console (waptconsole).
The network communications between these different components.
In complement to the elements listed above, an Organization that uses WAPT will have to choose and follow a methodology that is adapted to her use case:
Insure the safe provisioning of all other files that are to be incorporated into a WAPT package.
Develop the WAPT package python
setup.pyscript so as to avoid any exploitable security or confidentiality defect.Manage in a safe way the private keys for signing the packages.
Manage in a safe way the Authorities of Certification and Revocation for the SSL and HTTPS certificates.
The safe management of these complementary elements is excluded from the perimeter of this documentation.
Description of typical users¶
The following roles must be understood to evaluate the security principles incorporated in WAPT:
User
A User is an individual/ user of a WAPT equipped end-device (Enterprise and Discovery).
Package Deployer
A Package Deployer is an individual with the ability to sign packages that DO NOT contain python code (generally group, host and unit packages) and with the ability to upload the package to the main repository (Enterprise).
Package Developer
A Package Developer is an individual with the ability to sign any package, may it include or not include python code, and to upload the package to the main repository (Enterprise);
Note
The distinction between Package Deployer and Package Developer only exists in the Enterprise version of WAPT.
SuperAdmin
The SuperAdmin is an individual with all rights within WAPT.
Local Administrator
A Local Administrator is an individual with local administration right of the WAPT equipped end-devices (Enterprise and Discovery);
Note
Depending on the context within this documentation, an Administrator will have the meaning of a Package Deployer, Package Developer or SuperAdmin.
Note
The Users that are members of the Active Directory security group waptselfservice are considered to be Local Administrators from the point of view of WAPT security.
Description of the sensitive assets in WAPT¶
By definition, a sensitive asset is a data (or a function) that is considered as having value to an attacker.
Its value is estimated according to several security criteria (also called security needs):
Availability;
Integrity;
Confidentiality;
Authenticity.
The sensitive assets to protect are as follows:
Sensitive assets A1: communications¶
Communications between the central WAPT Server and the WAPT agents, as well as the communications between the WAPT console and the WAPT Server are a sensitive asset and they must be protected.
Note
Need for securing the communications
Integrity;
Confidentiality;
Authenticity.
Sensitive asset A2: inventory data¶
The informations on the state of deployment of the packages, as well as hardware and software configurations of the end-devices are a sensitive asset and they must be protected.
Note
Security need of the inventory data
Integrity;
Confidentiality.
Sensitive asset A3: log journals¶
The logs generated by WAPT on the central server and by the agents are a sensitive asset and they must be protected.
Note
Security needs of historical logs
Availability.
Sensitive asset A4: configuration values¶
The configuration values (HTTPS server keys, database access configuration, server authentication configuration) are sensitive and they must be protected.
Note
Security needs of configuration values
Integrity;
Confidentiality.
Sensitive asset A5: WAPT executables on the end-devices¶
The WAPT executables installed on managed clients are a sensitive asset
and they must be protected (i.e. the content of the <WAPT> directory
that includes the binaries, the configuration files and the local database).
Note
Security needs of configuration values
Integrity.
Sensitive asset A6: authentication¶
Authentication to the administration console as well as the authentication of the clients on the WAPT Server are a sensitive asset and they must be protected (public key of each WAPT agent).
Note
Security need of the authentication
Integrity;
Confidentiality.
Description of hypotheses on WAPT’s working environment¶
By definition, the hypotheses are statements on WAPT’s usage context or its working environment.
The following hypotheses on WAPT’s working environment must be considered:
Hypothesis H1: the Administrators and the Package Deployers are trained¶
The Administrators and the Package Deployers are trained on WAPT usage. In particular, they must insure that their logins, passwords and private keys are kept secret.
Hypothesis H2: the operating systems underlying WAPT are sane¶
WAPT’s underlying operating systems implement adequate protection mechanisms that are configured according to good practice (confinement, access control, etc).
The underlying operating system are patched and up to date at the time of the installation of WAPT, they are free of viruses, trojan horses, etc.
Hypothesis H3: the binaries necessary for WAPT to operate are sane¶
All libraries and tools necessary to install WAPT are considered to be sane. Upon the WAPT agent receiving a request, the agent verifies that the request has been properly signed.
Hypothesis H4: the WAPT packages are built in a safe manner¶
The Administrator is responsible for insuring that the files to be incorporated into a WAPT package come from safe sources and are free of viruses, trojan horses, etc.
Hypothesis H5: the Users of the end-devices are not Local Administrators¶
A User must not have local administration rights on the WAPT equipped device. Otherwise, the User must be considered a Local Administrator.
In particular, a User must not have write access to WAPT’s installation directory.
Hypothesis H6: the Local Administrators are trained¶
The Local Administrator of a device must be trained to use WAPT, or at minimum he must not make changes to files located in WAPT’s installation folder.
Description of threats on WAPT’s sensitive assets¶
By definition, a threat is an action or an event susceptible to bring prejudice to the security of the WAPT equipped device.
The threat agents to be considered for evaluating security in WAPT are as follows:
Unauthorized entities: it is a human attacker or an entity that interacts with WAPT without legitimately having access to it.
Note
The Administrators and the Local Administrators are not considered to be attackers.
The threats bearing on WAPT’s sensitive assets defined above are as follow:
Description of WAPT’s security functions¶
By definition, security functions are the set of technical measures and mechanisms implemented to protect in a proportionate way the sensitive assets against identified threats.
Security function F1: access authentication¶
Security function F1A: authentication of a device on initial registration in the WAPT database¶
New in version 1.5.
Note
risks avoided
The registering of an illegitimate device in the database.
A denial-of-service attack by overloading the database.
The insertion of a fraudulent inventory in the database.
Solution implemented¶
To exist in the database and thus to appear in the management console, a device must register with the WAPT Server using the register command.
The register command may be executed automatically when installing or updating the WAPT agent if the device has a kerberos machine account that is correctly registered in the Organization’s Active Directory domain.
If the device does not present to the WAPT Server a valid kerberos ticket, then the register fails;
Note
The kerberos registration method assumes that the Active Directory server is responsive at the time of launch of the register command.
Security function F1B: verification of server HTTPS certificates by the WAPT agents¶
New in version 1.5.
Note
risks avoided (notably MITM)
The sending of sensitive informations to an illegitimate and unauthorized WAPT Server.
The recovery of sensitive informations by an unauthorized entity.
The display of fake information in the management console of the Administrator.
An incorrect date to be sent upon a HEAD request, thus preventing future upgrades (request for a modified file date).
Sending the WAPT console password to an illegitimate and unauthorized WAPT Server.
Solution implemented¶
For the secured version of WAPT to work correctly:
An option for verifying the server HTTPS certificate is introduced in
C:\Program Files (x86)\waptwapt-get.inion the WAPT agents that will force the verification of the server certificate by the WAPT agents.An option for verifying the server HTTPS certificate is introduced in
C:\Program Files (x86)\waptwapt-get.inion the WAPT agents that will force the verification of the server certificate by the WAPT console.
Technically, it may be implemented in two ways:
By using a certificate verification tool implemented in the configuration file of WAPT’s Nginx web server; this method is typically provided by a Certificate Authority that is trusted by your network.
By using the certificate pinning method, which consists of providing the WAPT agent a short list of trusted certificates that will be stored in
C:\Program Files (x86)\wapt\ssl\server.
Security function F1C: no listening port on the WAPT agents¶
New in version 1.5.
Note
risks avoided
An unauthorized entity using an open port fraudulently.
Solution implemented¶
The connections to the WAPT Server are initiated exclusively by the agents, and the forced immediate actions are relayed through a permanent websocket initiated by the WAPT agent (update/ upgrade/ install …).
Note
if HTTPS is activated, then the WAPT agent checks that the websocket is connecting to the rightful server.
Security function F1D: signature of inventory return states¶
New in version 1.3.12.13.
Note
risks avoided
An unauthorized entity sending a fake inventory for a device that rightfully exists in the database.
Solution implemented¶
On the first register, each device generates a key/ certificate pair that is stored in
C:\Program Files (x86)\wapt\private, only accessible in read-only mode to Local Administrators. Once the device has successfully registered, the public key is sent to the WAPT Server.When the inventory is updated, the new inventory status is sent along with the private key of the device. The new inventory is then decrypted with the public key stored in the database.
The server will refuse any inventory that is signed with a wrong key.
Security function F2: protecting the integrity of the installation process of WAPT packages¶
Security function F2A: signature of WAPT packages¶
Note
risks avoided
To avoid an unauthorized entity modifying the content or the behavior of a WAPT package.
Solution implemented¶
When an Administrator or a Package Deployer builds a WAPT package, the file
manifest.sha256is created that lists the control sums of all files in the package.A file
signature.sha256encrypted with the WAPT agent’s private key is then created in the folderWAPT; it contains the control sum of the filemanifest.sha256.The whole is then compressed and suffixed with a .wapt extension.
When a WAPT agent downloads a WAPT package, the agent checks that the file
signature.sha256has been signed with the private key that matches the certificate present in the folderWAPT.The WAPT agent then checks that the certificate or the chain of certificates in
certificate.crthas been signed with a key matching one of the certificates present in the folderC:\Program Files (x86)\wapt\ssl.The WAPT agent then generates the control sum of all the files contained in the package (except the files
signature.sha256andcertificate.crt) and verifies that it matches the filemanifest.sha256contained in the package.If one of these steps does not pass, this means that a file has been modified/ added/ removed. The execution of the
setup.pyis then canceled.The altered package is then deleted from the local cache and the event is journalized in the logs of the agent.
Note
Since the version 1.5 of WAPT, the format of the manifest file
has changed from sha1 to sha256.
Security function F2B: signature of the attributes in the control files¶
New in version 1.4.
Note
risks avoided
An unauthorized entity modifying WAPT dependencies on WAPT equipped devices by falsifying
https://waptserver/wapt/Packages.
Solution implemented¶
When a WAPT package is signed, the sensitive attributes of the package are listed inside the signed_attributes attribute of the control file.
Note
Example of a signed_attributes list:
package, version, architecture, section, priority, maintainer, description, depends, conflicts, maturity, locale, min_os_version, max_os_version, min_wapt_version, sources, installed_size, signer, signer_fingerprint, signature_date, signed_attributes,
The attributes listed in signed_attributes are signed with the private key
of the Administrator and stored in the attribute signature
of the control file.
The certificate matching the private key is stored
in WAPT\certificate.crt inside the WAPT package.
On the WAPT Server, the index Packages is regenerated
when the wapt-scanpackages command is triggered by adding
or removing a package.
The WAPT Server extracts from each package the certificate of the signer
and adds it in the Packages zip file in the directory ssl.
Each certificate is named after its hexadecimal encoded fingerprint.
When the WAPT agent launches an update, it downloads
the Packages index file that contains the signed attributes
of all available packages and the certificates of the signers.
If the signer’s certificate is approved, which means that the certificate has been signed by a Trusted Certificate Authority or that the certificate itself is trusted, AND if the signer’s certificate can verify the attributes’ signature, the package is added to the index of available packages. Otherwise it is ignored.
Security function F2C: access restriction to the installation folder of the WAPT agent¶
Note
risks avoided
An unauthorized entity modifying the behavior of a WAPT agent.
The installation folder C:\Program Files (x86)\wapt is accessible in
read-write mode:
To the Local Administrators by direct access to the installation folder of the WAPT agent on the device.
To the Administrators through the deployment of WAPT agent upgrades.
Neither the Package Deployers, nor the Users have write-access to the WAPT agent’s installation folder.
Security function F2D: total access restriction to the folder storing the key / certificate for inventory signing¶
Note
risks avoided
An unauthorized entity falsifying an inventory status update.
An unauthorized entity impersonating the identity of a WAPT equipped device.
No access right is granted to any User
to C:\Program Files (x86)\wapt\private, whomever he may be.
Only the WAPT agent has a write and read access to this folder.
Note
This method for storing the key and the certificate results from a technical design choice that says that the WAPT equipped device would embed any and all information related to itself.
Security function F3: securing the communications between the different components of WAPT¶
Security function F3A: signature of immediate action calls sent to the WAPT agents¶
New in version 1.5.
Note
risks avoided
An unauthorized entity sending falsified requests to the WAPT agents.
Solution implemented¶
The following commands are signed by the WAPT Server before being relayed to the targeted WAPT agents via their Websockets:
wapt-get install: requests the WAPT agent to install a WAPT package flagged as MISSING.wapt-get remove: requests the WAPT agent to remove a package.wapt-get forget: requests the WAPT agent to forget the existence of a previously installed WAPT package without removing the software or the configuration.wapt-get update-status: requests the WAPT agent to send its current inventory status to the WAPT Server.wapt-get upgrade: requests the WAPT agent to execute a package flagged as NEED UPGRADE.wapt-get update: requests the WAPT agent to update the list of available packages.
All the attributes in the requests for immediate action are signed:
The device’s UUID;
The action (ex: install);
The arguments (ex: tis-firefox);
The timestamp of the requests.
The certificate matching the signature is passed along:
Upon receiving a request, the WAPT agent verifies that the request has been properly signed.
The agent will the verify that the timestamp is within a one minute delay window.
Ultimately, the agent will verify that the certificate is authorized to launch actions.
Presentation of cryptographic processes¶
Date |
Sep 20, 2024 |
Written by |
Hubert TOUVET |
Applicable for WAPT |
>= 1.5.0.17 |
Version of the Document |
1.5.0.17-0 |
Cryptographic processes are used in the following activities:
Signature and verification of the files contained in a package.
Signature and verification of the attributes of a package.
Signature and verification of instantaneous actions on the WAPT clients.
Signature of inventories and status of WAPT clients.
Authentication of the WAPT client Websocket connections on the WAPT server.
HTTPS communication between the WAPT clients and the WAPT Server.
HTTPS communication between the WAPT console and the WAPT Server.
HTTPS communication between the WAPT clients and the WAPT repositories.
Folders and files referenced in this document¶
<WAPT>: WAPT installation folder. By default%Program Files (x86)%WAPT.<WAPT>wapt-get.ini: WAPT client configuration file (wapt-get and waptservice).<WAPT>ssl: default directory for signed actions and trusted certificates.<WAPT>sslserver: default directory for storing HTTPS server certificates (pinning).<WAPT>private: default certificate directory for signing the inventory and the Websocket connections.%LOCALAPPDATA%waptconsolewaptconsole.ini: configuration file for the console and package development actions for the wapt-get tool.%appdata%waptconsolessl: default trusted certificate directory for importing packages from an external repository (i.e. package templates).
Definitions of Actors¶
Organization
An Organization is the realm of responsibility within which WAPT is used.
Certificate Authority
A Certificate Authority is the entity that keeps the keys that have been used to sign certificates for the Package Developers, the Package Deployers and the HTTPS servers.
Administrators
Administrators have a personal RSA key and a certificate that has been signed by the Certificate Authority of the Organization; they also have a login and a password for accessing the WAPT console.
WAPT clients
WAPT clients are the realm of devices that the Organization has allowed the Administrators to manage with WAPT. The clients may or may not be a member of the Organization’s Active Directory domain.
WAPT Server
The WAPT Server is the Linux / Nginx/ PostgreSQL that the Organization uses to keep the inventory of WAPT equipped devices.
By default, the WAPT Server also plays the role of an internal WAPT Repository. The WAPT Server has a machine account in the Organization’s Active Directory.
Internal WAPT repositories
Internal WAPT repositories are one or several Linux/ Nginx servers that deliver signed WAPT packages to WAPT clients using the HTTPS protocol.
External WAPT repositories
External WAPT repositories are a public WAPT repository that the Package Developers may use to import packages designed by other Organizations, under the condition that they check the adequacy of the WAPT package in regards the internal policies on security and safety;
Active Directory Server
The Active Directory Server manages the Organization’s AD domain;
Summary of crypto modules present in WAPT¶
Todo
sfonteneau
On the client side of WAPT (WAPT 1.5.0.12):
Python 2.7.13 standard ssl module linked on OpenSSL 1.0.2j 26 Sep 2016: used for the HTTPS connections between the WAPT clients and the WAPT server.
cryptography==1.9 linked on openssl 1.1.0f: used for all RSA crypto operations such as key generations, X509 certificate generations and signature verifications.
kerberos-sspi==0.2 and requests-kerberos==0.11.0: used for authenticating the WAPT client on its first registering on the WAPT Server.
pyOpenSSL==17.0.0: used to recover the WAPT Server certificate chain.
certifi==2017.4.17: used as base for the Root Authorities certificates.
Openssl 1.0.2l dll: used in waptcommon.pas written with the FPC Indy library and the TIdSSLIOHandlerSocketOpenSSL class.
On the server side of WAPT:
nginx/1.10.2: configured for TLS1.2, cipher ‘EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH’.
python 2.7.5 standard ssl module linked on OpenSSL 1.0.1e-fips 11 Feb 2013.
cryptography==1.9 linked on OpenSSL 1.0.1e-fips 11 Feb 2013: used for all RSA crypto operations such as key generations, X509 certificate generations and signature verifications.
Key and certificate management for the Administrators¶
Packages and actions done by an Administrator are signed so that only Trusted Administrators are authorized to manage the devices.
The WAPT Administrator holds:
A private 2048 bit RSA key that has been encrypted by the aes-256-cbc algorithm.
A X509 certificate signed by an Certificate Authority trusted by the Organization.
Note
The process for creating the keys and signing, distributing and revocating the certificates are of the responsibility of the Organization using WAPT; that process is beyond the functional perimeter of WAPT.
However, to make the testing of WAPT easy, WAPT offers a function to generate a RSA key and its corresponding X509 certificate:
The generated RSA key is 2048bit long, encrypted with aes-256-cbc, encoded in PEM format and saved with a .pem extension.
The certificate is either self-signed, or signed by a Trusted Authority from whom we have received a key and a PEM formated certificate.
If the certificate is self-signed, then its KeyUsage attribute contains the keyCertSign flag.
If the Administrator is authorized by the Organization to sign packages that contain python code (the presence of a
setup.pyfile is detected in the package), the extendedKeyUsage attribute of the certificate contains the CodeSigning flag.The X509 certificate is encoded and handed over to the Administrator in PEM format with a .crt extension.
Validity of the Administrator’s certificate¶
For WAPT version up to 1.5.0.12, WAPT agent does not verify the revocation state of the Administrator’s certificate during the process of verifying the package, the attributes or the actions of the Administrator.
It only checks the dates of validity (notValidBefore/ notValidAfter attributes). The certificate is valid if (Now >= notValidBefore and Now <= notValidAfter).
Managing the WAPT agent’s key and certificate¶
The WAPT client (waptservice) uses RSA keys and X509 certificates to interact with the WAPT Server.
The WAPT client certificate is used in the following situations:
When updating the WAPT client status on the server (update_server_status) signing informations.
When the WAPT agent establishes a Websocket with the server (waptservice) signing the WAPT client UUID.
First emission and later update of the WAPT agent’s certificate¶
On finishing the installation process of the WAPT agent on the device, the WAPT agent automatically registers itself on the WAPT Server by sending a kerberos authenticated HTTPS request that uses the TGT of the machine account.
The WAPT agent uses Windows kerberos APIs implemented with kerberos-sspi and requests-kerberos python modules.
Note
this process works if and only if the device is joined to the Windows domain for which the WAPT Server is configured.
If the key and the certificates have not yet been generated, or if they do not match the current FQDN of the device, the WAPT agent generates a self-signed RSA key and X509 certificate with the following parameters:
The key is 2048 bit RSA encoded in PEM format and stored in the file
<WAPT>private<device FQDN>.pem.The generated certificate has the following attributes:
Subject.COMMON_NAME = <device FQDN>.
Subject.ORGANIZATIONAL_UNIT_NAME = name of the Organization registered in the WAPT client’s Windows registry.
SubjectAlternativeName.DNSName = <device FQDN>.
BasicConstraint.CA = True.
Validity = 10 years.
Serialnumber = random;
The certificate is saved in the
<WAPT>private<device FQDN>.crt.Note
Only machine accounts and Local Administrators have access to the
<WAPT>privatedirectory because specific ACLs have been applied upon first installation of the WAPT agent on the device.The inventory and the WAPT agent status updates are sent to the WAPT Server over POST HTTPS requests;
The POST HTTPS requests are authenticated by adding two specific headers:
X-Signature:
JSON encoded BLOB of inventory or status informations.
signature of the JSON file with the private key of the WAPT Client: sha256 hashing and PKCS#1 v1.5 padding.
base64 encoding of the signature.
X-Signer: Subject.COMMON_NAME or UUID of the WAPT Client.
After having initially authenticated the WAPT client with kerberos, the WAPT Server receives the certificate sent by the Client and stores it in the table hosts of its inventory in PEM format (column host_certificate).
Note
If the device is renamed, the key/ certificate pair is regenerated.
When the WAPT agent will update its status with the WAPT Server, the POST request will be refused because the remote device is registered in the database with another certificate.
The device will then retry to register with the WAPT Server using kerberos; then the new certificate will be saved in the database.
HTTPS communication between the WAPT clients and the WAPT repositories¶
Websocket communications between the WAPT clients and the WAPT Server¶
To allow immediate actions on the WAPT clients, the WAPT service deployed on the clients establishes and maintains a permanent Websocket with the WAPT server.
This connection is TLS encrypted and uses on the client side the same bundle of certificates as the HTTPS connexion from the WAPT client to the WAPT Server.
Communications between the WAPT console and the WAPT Server¶
Deploying certificates of Authorities of Certification¶
verify_cert parameter in section [global] in file
%LOCALAPPDATA%waptconsolewaptconsole.ini:
verify_cert = 1
this method will only work well if the HTTPS server is configured to send its certificate and the intermediary certificates upon initialization of the TLS connexion.
verify_cert = <path to .pem>
check the HTTPS certificate using the indicated bundle of certificates. All the certificates of the intermediary Certificate Authorities must be bundled in a .pem formated file;
verify_cert = 0
do not verify the HTTPS certificate of the server;
Conventionally, the approved bundle of certificates from the
Certificate Authority is stored in the <WAPT>sslserver
directory.
The WAPT console includes a function that facilitates the initial recovery
of the server certificate chain and that stores it in .pem format
in the <WAPT>sslserver<server FQDN>.
The Administrator is responsible for insuring that the recovered certificate chain is authentic.
It is also possible to recover the server certificate chain and fill
out the verify_cert parameter with the command line
wapt-get enable-check-certificate.
Process for signing a package¶
The process for signing a package is launched with the following actions:
action
wapt-get.exe build-upload <directory>.action
wapt-get.exe sign-package <path-to-package-file.wapt>.shell command
wapt-signpackage.py <WAPT-package-list>.saving a host package in the WAPT console.
saving a group package in the WAPT console.
importing a package from an external repository.
creating a package with the MSI setup wizard.
Initial parameters¶
ZIP file of the package;
.pem formated RSA private key of the certificate holder (encrypted with OpenSSL’s aes-256-cbc algorithm if the key has been created in the WAPT console);
X509 certificate of the certificate holder matching the private key;
if the package to be signed contains a
setup.pyfile, then the X509 certificate must have the advanced Key Usage extension codeSigning (1.3.6.1.5.5.7.3.3);
Signing the attributes in the control file¶
The control file defines the metadata of a package and in particular
its name, its version, its dependencies and its conflicts. It is
the identity card of the WAPT package.
These metadata are primarily used by the WAPT agent to determine whether a package must be upgraded, and what packages must be first installed or removed.
The package attributes are therefore signed to insure the integrity and the authenticity of the WAPT package.
Process steps:
The attributes signed_attributes, signer, signature_date, signer_fingerprint are added to the structure of the
controlfile:signed_attributes: comma separated list of the names of the attributes;
signer: CommonName of the certificate holder;
signature_date: current date and time (UTC) in ‘%Y-%m-%dT%H:%M:%S format;
signer_fingerprint: hexadecimal encoded
sha256fingerprint of the fingerprint obtained with the fingerprint function included in the cryptography.x509.Certificate class.
The attributes of the control structure are JSON encoded.
The resulting JSON BLOB is signed with sha256 hashing and PKCS#1 v1.5 padding.
The signature is base64 encoded and stored as a signature attribute in the
controlfile.
Signing the files of the package¶
The
controlfile attributes are signed and serialized in JSON format. The result is stored in the<WAPT>controlfile of the WAPT package.The PEM serialized X509 certificate of the certificate holder is stored in the
<WAPT>certificate.crtfile of the WAPT package.The sha256 fingerprints of the all files contained in the WAPT package are hexadecimal encoded and stored as a JSON list [(filename,hash),] in the
<WAPT>manifest.sha256file in the WAPT package.The content of the file
<WAPT>manifest.sha256is signed with the private key of the Administrator (2048 bit RAS key), sha256 hashed and PKCS#1 v1.5 padded:The signature process relies on the signing function of the cryptography.rsa.RSAPrivateKey.signer class.
cryptography.rsa.RSAPrivateKey.signer relies on the OpenSSL functions of EVP_DigestSignInit.
The signature is base64 serialized and stored in the file
<WAPT>signature.sha256of the WAPT package.
Verifying the signature of a package attributes¶
The verification takes place:
When the index file of available packages on the WAPT client is updated from the
Packagesindex file on the repository.When a package signature is verified (installation, download) when not in development mode, i.e. if the installation takes place from a ZIP file and not from a development directory.
The verification consists of:
Reading the control attributes from the WAPT package’s
controlfile.Recovering the X509 certificate from the certificate holder from the WAPT package’s
certificate.crtfile.Decoding the base64 formated signature attribute.
Constructing a JSON structure with the attributes to be signed (such as defined in the PackageEntry class).
Verifying if the public key of the holder’s certificate can verify the hash of the JSON structured list of attributes and the signature of the
controlfile, using sha256 hashing and PKCS#1 v1.5 padding.Verifying whether the certificate is trusted (either it is present in the list of trusted certificates, or signed by a Trusted Certificate Authority).
In case we must verify the attributes without having the WAPT package on hand,
we recover the list of certificates of potential certificate holders
from the Packages index file on the WAPT repository.
The certificates are named ssl/<hexadecimal formated certificate
fingerprint>.crt.
An attribute in the WAPT package’s control file specifies
the fingerprint of the control file’s certificate holder.
Verifying the signature of a WAPT package¶
The verification takes place:
When installing a package on a WAPT client.
When editing an existing package.
When importing a package from an external repository (if the checkbox is checked in the WAPT console).
The verification consists of:
Recovering the X509 certificate from the certificate holder from the WAPT package’s
certificate.crtfile.Verifying that the certificate has been signed by a Trusted Authority whose certificate is present in the folder
sslon the WAPT client.Verifying the signature of the file
manifest.sha256with the public key.
Signing immediate actions¶
From the WAPT console, the Administrators may launch actions directly on the WAPT clients connected with the WAPT Server using Websockets.
The WAPT console signs these actions with the key and certificate of the Administrator before sending them to the WAPT Server using an HTTPS POST request; the request is then forwarded to the targeted WAPT clients.
Possible immediate actions are:
trigger_host_update.
trigger_host_upgrade.
trigger_install_packages.
trigger_remove_packages.
trigger_forget_packages.
trigger_cancel_all_tasks.
trigger_host_register.
Signing process for immediate actions¶
The action is defined by its name and the actions attributes. The attributes are uuid, action, force, notify_server, and packages (for actions implicating a list of packages).
The attributes signed_attributes, signer, signature_date, signer_certificate are added to the structure of the action:
signed_attributes list of the attributes that are signed.
signer Subject.COMMON_NAME of certificate holder.
signature_date: current date and time (UTC) in ‘%Y-%m-%dT%H:%M:%S’ format.
signer_certificate certificate holder’s base64 encoded X509 certificate.
The structure is JSON encoded.
The signature of the JSON file is calculated from the RSA private key of the signer using a sha256 hash algorithm and a PKCS1 v1.5 padding.
The signature is base64 encoded and stored on the signature attribute inside the JSON file.
Verifying the signature of an immediate action¶
From the WAPT console, the Administrators may launch actions directly on the WAPT clients connected with the WAPT Server using Websockets.
The actions are JSON encoded, signed with the key and certificate of the Administrator, and relayed to the targeted WAPT clients by the WAPT Server.
Possible immediate actions are:
trigger_host_update.
trigger_host_upgrade.
trigger_install_packages.
trigger_remove_packages.
trigger_forget_packages.
trigger_cancel_all_tasks.
trigger_host_register.
The action get_tasks_status does not require SSL authentication.
Upon receiving an event on the Websocket connexion of the WAPT client:
The X509 certificate of the certificate holder is extracted from the JSON file (format PEM).
The WAPT client tests whether the certificate is to be trusted, i.e. that it is present in
<WAPT>sslor that it has been signed by a Trusted Authority (certificate of the Authority present in<WAPT>ssl).The WAPT client checks whether the certificate can verify the signature that is present in the JSON structure of the action, which consists of:
Extracting the base64 encoded signature from the signature attribute in the JSON file;
Extracting the signature date formated in ‘%Y-%m-%dT%H:%M:%S’ from the signature_date attribute;
Checking that the signature date is neither too old in the past, nor too late into the future by over 10 minutes;
Reconstructing a JSON representation of the attributes of the action;
Checking that the certificate’s public key can verify the JSON file with the signature by using a sha256 hash algorithm and a PKCS1 v1.5 padding.
Verifying the complete download of a package¶
For each package, a md5 sum of the package is calculated and stored
in the Packages index file of the repository.
When installing a package, the WAPT client checks whether a local version
of the package is already available in the cache directory <WAPT>cache.
If the package file is cached, its md5 sum is calculated and compared with the md5 sum in the index file. If they are different, the cached package is deleted.
This md5 sum is only used to insure that a package has been fully downloaded.
The checking of the signature of the package will be used instead of the md5 sum to fully insure the integrity and the authenticity of the WAPT package.