Credential access represents techniques resulting in access to or control over system, domain, or service credentials that are used within an enterprise environment. Adversaries will likely attempt to obtain legitimate credentials from users or administrator accounts (local system administrator or domain users with administrator access) to use within the network. This allows the adversary to assume the identity of the account, with all of that account's permissions on the system and network, and makes it harder for defenders to detect the adversary. With sufficient access within a network, an adversary can create accounts for later use within the environment.
Below is a list of all the Credential Access techniques in ATT&CK:
|Brute Force||Credential Access||Adversaries may use brute force techniques to attempt access to accounts when passwords are unknown or when password hashes are obtained.
Credential Dumping to obtain password hashes may only get an adversary so far when Pass the Hash is not an option. Techniques to systematically guess the passwords used to compute hashes are available, or the adversary may use a pre-computed rainbow table. Cracking hashes is usually done on adversary-controlled systems outside of the target network.1Adversaries may attempt to brute force logins without knowledge of passwords or hashes during an operation either with zero knowledge or by attempting a list of known or possible passwords. This is a riskier option because it could cause numerous authentication failures and account lockouts, depending on the organization's login failure policies.2
|Credential Dumping||Credential Access||Credential dumping is the process of obtaining account login and password information from the operating system and software. Credentials can be used to perform Lateral Movement and access restricted information.
Tools may dump credentials in many different ways: extracting credential hashes for offline cracking, extracting plaintext passwords, and extracting Kerberos tickets, among others. Examples of credential dumpers include pwdump7, Windows Credential Editor, Mimikatz, and gsecdump. These tools are in use by both professional security testers and adversaries.Plaintext passwords can be obtained using tools such as Mimikatz to extract passwords stored by the Local Security Authority (LSA). If smart cards are used to authenticate to a domain using a personal identification number (PIN), then that PIN is also cached as a result and may be dumped.3
|Credential Manipulation||Credential Access||Account creation and manipulation may aid adversaries in maintaining access to credentials and certain permission levels within an environment. Manipulation could consist of creating new credentials, modifying permissions, adding or changing permission groups, modifying account settings, or modifying how authentication is performed. In order to create or manipulate accounts, the adversary must already have sufficient permissions on systems or the domain.|
|Credentials in Files||Credential Access||Adversaries may search local file systems and remote file shares for files containing passwords. These can be files created by users to store their own credentials, shared credential stores for a group of individuals, configuration files containing passwords for a system or service, or source code/binary files containing embedded passwords. It is possible to extract passwords from backups or saved virtual machines through Credential Dumping.4 Passwords may also be obtained from Group Policy Preferences stored on the Windows Domain Controller.5|
|Exploitation of Vulnerability||Credential Access|
|Exploitation of a software vulnerability occurs when an adversary takes advantage of a programming error in a program, service, or within the operating system software or kernel itself to execute adversary-controlled code. Exploiting software vulnerabilities may allow adversaries to run a command or binary on a remote system for lateral movement, escalate a current process to a higher privilege level, or bypass security mechanisms. Exploits may also allow an adversary access to privileged accounts and credentials. One example of this is MS14-068, which can be used to forge Kerberos tickets using domain user permissions.67|
|Adversaries can use methods of capturing user input for obtaining credentials for Legitimate Credentials and information Collection that include keylogging and user input field interception.
Keylogging is the most prevalent type of input capture, with many different ways of intercepting keystrokes,8 but other methods exist to target information for specific purposes, such as performing a UAC prompt or wrapping the Windows default credential provider.9
Keylogging is likely to be used to acquire credentials for new access opportunities when Credential Dumping efforts are not effective, and may require an adversary to remain passive on a system for a period of time before an opportunity arises.Adversaries may also install code on externally facing portals, such as a VPN login page, to capture and transmit credentials of users who attempt to log into the service. This variation on input capture may be conducted post-compromise using legitimate administrative access as a backup measure to maintain network access through External Remote Services and Legitimate Credentials or as part of the initial compromise by exploitation of the externally facing web service.10
|Network Sniffing||Credential Access||Network sniffing refers to using the network interface on a system to monitor or capture information sent over a wired or wireless connection. User credentials may be sent over an insecure, unencrypted protocol that can be captured and obtained through network packet analysis. An adversary may place a network interface into promiscuous mode, using a utility to capture traffic in transit over the network or use span ports to capture a larger amount of data. In addition, Address Resolution Protocol (ARP) and Domain Name Service (DNS) poisoning can be used to capture credentials to websites, proxies, and internal systems by redirecting traffic to an adversary.|
|Two-Factor Authentication Interception||Credential Access||Use of two- or multifactor authentication is recommended and provides a higher level of security than user names and passwords alone, but organizations should be aware of techniques that could be used to intercept and bypass these security mechanisms. Adversaries may target authentication mechanisms, such as smart cards, to gain access to systems, services, and network resources.
If a smart card is used for two-factor authentication (2FA), then a keylogger will need to be used to obtain the password associated with a smart card during normal use. With both an inserted card and access to the smart card password, an adversary can connect to a network resource using the infected system to proxy the authentication with the inserted hardware token.11
Other methods of 2FA may be intercepted and used by an adversary to authenticate. It is common for one-time codes to be sent via out-of-band communications (email, SMS). If the device and/or service is not secured, then it may be vulnerable to interception. Although primarily focused on by cyber criminals, these authentication mechanisms have been targeted by advanced actors.12Other hardware tokens, such as RSA SecurID, require the adversary to have access to the physical device or the seed and algorithm in addition to the corresponding credentials.
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- Cylance. (2014, December). Operation Cleaver. Retrieved December 4, 2014.
- Delpy, B. (2014, September 14). Mimikatz module ~ sekurlsa. Retrieved January 10, 2016.
- CG. (2014, May 20). Mimikatz Against Virtual Machine Memory Part 1. Retrieved November 12, 2014.
- Security Research and Defense. (2014, May 13). MS14-025: An Update for Group Policy Preferences. Retrieved January 28, 2015.
- Microsoft. (2014, November 18). Vulnerability in Kerberos Could Allow Elevation of Privilege (3011780). Retrieved December 23, 2015.
- Metcalf, S. (2015, May 03). Detecting Forged Kerberos Ticket (Golden Ticket & Silver Ticket) Use in Active Directory. Retrieved December 23, 2015.
- Tinaztepe, E. (n.d.). The Adventures of a Keystroke: An in-depth look into keyloggers on Windows. Retrieved April 27, 2016.
- Wrightson, T. (2012, January 2). CAPTURING WINDOWS 7 CREDENTIALS AT LOGON USING CUSTOM CREDENTIAL PROVIDER. Retrieved November 12, 2014.
- Adair, S. (2015, October 7). Virtual Private Keylogging: Cisco Web VPNs Leveraged for Access and Persistence. Retrieved March 20, 2017.
- Mandiant. (2011, January 27). Mandiant M-Trends 2011. Retrieved January 10, 2016.
- Sancho, D., Hacquebord, F., Link, R. (2014, July 22). Finding Holes Operation Emmental. Retrieved February 9, 2016.