Steal or Forge Kerberos Tickets: Ccache Files

Adversaries may attempt to steal Kerberos tickets stored in credential cache files (or ccache). These files are used for short term storage of a user's active session credentials. The ccache file is created upon user authentication and allows for access to multiple services without the user having to re-enter credentials.

The /etc/krb5.conf configuration file and the KRB5CCNAME environment variable are used to set the storage location for ccache entries. On Linux, credentials are typically stored in the /tmp directory with a naming format of krb5cc_%UID% or krb5.ccache. On macOS, ccache entries are stored by default in memory with an API:{uuid} naming scheme. Typically, users interact with ticket storage using kinit, which obtains a Ticket-Granting-Ticket (TGT) for the principal; klist, which lists obtained tickets currently held in the credentials cache; and other built-in binaries.[1][2]

Adversaries can collect tickets from ccache files stored on disk and authenticate as the current user without their password to perform Pass the Ticket attacks. Adversaries can also use these tickets to impersonate legitimate users with elevated privileges to perform Privilege Escalation. Tools like Kekeo can also be used by adversaries to convert ccache files to Windows format for further Lateral Movement. On macOS, adversaries may use open-source tools or the Kerberos framework to interact with ccache files and extract TGTs or Service Tickets via lower-level APIs.[3][4][5][6]

ID: T1558.005
Sub-technique of:  T1558
Platforms: Linux, macOS
Version: 1.0
Created: 17 September 2024
Last Modified: 14 October 2024

Procedure Examples

ID Name Description
S0357 Impacket

Impacket tools – such as getST.py or ticketer.py – can be used to steal or forge Kerberos tickets using ccache files given a password, hash, aesKey, or TGT.[1][7]

Mitigations

ID Mitigation Description
M1047 Audit

Enable and perform audits or scans of systems, permissions, insecure software, insecure configurations, etc. to identify potential weaknesses.[5] For example, use auditd to audit access to hashes, machine tickets, or /tmp files. If using sssd and Vintela, ensure kerberos is disabled if not being used.[8]

M1043 Credential Access Protection

Protect resources with Security Enhanced Linux (SELinux) by defining entry points, process types, and file labels.[5]

Detection

ID Data Source Data Component Detects
DS0022 File File Access

Monitor for abnormal read access to ccache files located in the /tmp directory of a system from non-user processes.

References