COOKIEJAR: Tracking Adversaries With FireEye Endpoint Security’s Logon
Tracker ModuleDuring a recent investigation at a telecommunications company led by
href="/content/fireeye-www/en_US/mandiant/managed-detection-and-response.html">Mandiant
Managed Defense, our team was tasked with rapidly identifying
systems that had been accessed by a threat actor using legitimate, but
compromised domain credentials. This sometimes-challenging task was
made simple because the customer had enabled the Logon Tracker module
within their FireEye href="/content/fireeye-www/en_US/products/endpoint-security.html">Endpoint
Security product.
Logon Tracker is an Endpoint Security Innovation Architecture module
designed to simplify the investigation of lateral movement within
Windows enterprise environments. Logon Tracker improves the efficiency
of investigating lateral movement by aggregating historical logon
activity and provides a mechanism to monitor for new activity. This
data is presented in a user interface designed for analyzing
investigative leads (e.g., a compromised account) and hunting for
suspicious activity (e.g., RDP activity by privileged accounts). Logon
Tracker also provides a graph interface that enables the
identification of irregular and unique logons with the option to
filter on hostnames, usernames, protocol, time of day, process name,
privilege level, status (success/failure), and more.
src="https://www.fireeye.com/content/dam/fireeye-www/blog/images/cookiejar/picture1.png" alt="" />
Figure 1: Logon Tracker GUI interface
A critical component of a successful incident response is the
scoping effort to identify systems that may have been accessed by the
adversary. Windows Event Logs offer a commonly utilized method of
identifying an adversary’s lateral movement between Windows systems.
However, as with all log sources, Windows Event Logs are subject to
data retention limits on endpoints, making the aggregated logon
activity provided by Logon Tracker a critical source of evidence for
incident response.
Logon Tracker’s graphical display along with the raw logon events
allowed Mandiant Managed Defense to quickly identify 10 potentially
compromised hosts and begin to create a timeline of adversary activity.
Managed Defense also leveraged Logon Tracker to monitor for
additional suspicious logons and adversary activity throughout the
incident response. Searching for logons (both failed and successful)
from known compromised accounts and activity originating from
compromised systems allowed our investigators to quickly determine
which systems should be prioritized for analysis. Additionally, Logon
Tracker provides investigators the ability to:
- Filter logon data for activity originating from user-provided
IP ranges - Search for logon data for activity by specific
privileged accounts, including “Domain Administrators” and
“Enterprise Administrators” - Search for any privileged logon
using the “Privileged” logon type - Provide alerting and
definition of custom rules (coming soon!)
Case Background
In mid-July, the Managed Defense Security Operations Center
identified potential credential harvesting activity on a Windows
server. The activity included the creation of a scheduled task
configured to execute the built-in Windows utility, NTDSUTIL to take a
snapshot of the active NTDS.dit file and save it locally to a text
file as shown in Figure 2:
"schtasks /s <redacted> /create
/tn ntbackup /tr \"ntdsutil snapshot \\\"activate
instance ntds\\\" create quit quit
>c:\\Users\\admin\\AppData\\Local\\Temp\\ntds.log\"
/sc once /st 05:38:00 /sd 07-12-2020 /f |
Figure 2: Scheduled task creation for NTDS.DIT harvesting
The NTDS.dit file is a database that contains Active Directory data
such as user objects, group memberships, groups, and—more useful to an
adversary—password hashes for all users in the domain.
Leveraging Logon Tracker and simple timeline analysis, Managed
Defense quickly determined an adversary had accessed this system to
create a scheduled task from a system with a hostname that did not
match the naming convention used within the environment. An anonymized
example of Logon Tracker data is shown in Figure 3:
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Figure 3: Logon Tracker data
Armed with the suspicious hostname and potentially compromised
username, Managed Defense then used Logon Tracker’s search
functionality to determine the scope of systems potentially accessed
by the adversary.
The resulting investigation revealed that an Internet-facing
Customer Relationship Management (CRM) application hosted on a Linux
Apache web server had been compromised. Multiple web shells had been
placed within web-accessible folders, allowing an adversary to execute
arbitrary commands on the server. The adversary leveraged one of these
web shells to install a malicious Apache module and restart Apache for
the module to take effect. Mandiant has classified this module as
COOKIEJAR (see the Malware Appendix at the end of the post for more
details). The COOKIEJAR module enabled the adversary to proxy through
the compromised server to any arbitrary IP/port pair within the
customer’s internal network, see Figure 4.
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Figure 4: PCAP data
Using this proxied access to the customer’s network, the adversary
leveraged previously compromised domain credentials to connect to
multiple Windows servers using SMB. Due to the use of the proxy to
connect into the customer’s network, the hostname of the adversary’s
workstation being used to conduct the attack was also passed into the
logon events. This type of activity occurs due to the direct
connection to the customers network and is similar to being on the
same LAN. The non-standard hostname and non-standard customer naming
convention used by the adversary help make scoping an easy task.
Additionally, Managed Defense was able to leverage network detection
to alert on the authentication attempts and activities of the
adversary’s host.
Malware Appendix
During the course of the response, Mandiant identified a customized
malicious Apache plugin capable of intercepting HTTP requests to an
Apache HTTP server. The new malware family COOKIEJAR was created to
aid in clustering and tracking this activity. The COOKIEJAR module
installs a pre-connection hook that only runs if the client IP address
matches a specified hardcoded adversary-controlled IP address. It
listens for SSL/TLS connections on the port specified by the Apache
server, using a certificate and private key loaded from
/tmp/cacert.pem and /tmp/privkey.pem respectively. If
the client IP address matches the hardcoded IP address (Figure 4), the
backdoor accepts three commands based on the start of the URL:
- /phpconf_t/: Simply writes
<html><h1>accepted.</h1></html> as the
response. Likely used to test if the server is infected with the
malware. - /phpconf_s/: Executes commands on the server. Any
communications to and from the system are forwarded to a shell, and
are AES-256-ECB encrypted and then Base58 encoded.
- /phpconf_p/: Decode the second encoded string provided as a
hostname/port (the first is ignored), using Base58 and AES-256-ECB
(same key as before). The server will connect to the remote host and
act as a proxy for the command and control (C2). Data to and from
the C2 is encoded using Base58 and AES-256-ECB. Data to and from the
remote host is not encoded.
src="https://www.fireeye.com/content/dam/fireeye-www/blog/images/cookiejar/picture5.png" alt="" />
Figure 5: Hardcoded configuration data
within COOKIEJAR
Detecting the Techniques
Product
|
Signature
|
Network Security/MVX | width="312" valign="top">
- APT.Backdoor.Linux64_COOKIEJAR_1
- APT.Backdoor.Linux_COOKIEJAR_1
- APT.Backdoor.Linux.COOKIEJAR
Acknowledgements
- Chris Gardner, Malware Analyst
- Fred House, Director,
Engineering
More information on FireEye Endpoint Security's
Logon Tracker Module
including the module download and user manual are available in the
FireEye Marketplace
. Learn more about href="/content/fireeye-www/en_US/mandiant/managed-detection-and-response.html">Mandiant
Managed Defense, and catch an on-demand recap on this and
the Top
5 Managed Defense attacks this year.
Source:
COOKIEJAR: Tracking Adversaries With FireEye Endpoint Security’s Logon
Tracker Module
