Two-Factor Authentication Interception

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Two-Factor Authentication Interception
Technique
ID T1111
Tactic Credential Access
Platform Windows Server 2003, Windows Server 2008, Windows Server 2012, Windows XP, Windows 7, Windows 8, Windows Server 2003 R2, Windows Server 2008 R2, Windows Server 2012 R2, Windows Vista, Windows 8.1
System Requirements

Smart card Proxy: Use of smart cards for single or multifactor authentication to access to network resources. Attached smart card reader with card inserted.

Out-of-band one-time code: Access to the device, service, or communications to intercept the one-time code.

Hardware token: Access to the seed and algorithm of generating one-time codes.
Permissions Required Administrator, SYSTEM
Contributors John Lambert, Microsoft Threat Intelligence Center

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.1

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.2

Other 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.

Examples

  • Sykipot is known to contain functionality that enables targeting of smart card technologies to proxy authentication for connections to restricted network resources using detected hardware tokens.3

Mitigation

Remove smart cards when not in use. Protect devices and services used to transmit and receive out-of-band codes.

Identify and block potentially malicious software that may be used to intercept 2FA credentials on a system by using whitelisting4 tools, like AppLocker,56 or Software Restriction Policies7 where appropriate.8

Detection

Detecting use of proxied smart card connections by an adversary may be difficult because it requires the token to be inserted into a system; thus it is more likely to be in use by a legitimate user and blend in with other network behavior.