## 10454006.r5.v1

# Malware Analysis Report 2023-09-05


## Notification

This report is provided "as is" for informational purposes only. The Department of Homeland Security (DHS) does not provide any
warranties of any kind regarding any information contained herein. The DHS does not endorse any commercial product or service
referenced in this bulletin or otherwise.

This document is marked TLP:CLEAR--Recipients may share this information without restriction. Sources may use TLP:CLEAR
when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public
release. Subject to standard copyright rules, TLP:CLEAR information may be shared without restriction. For more information on
the Traffic Light Protocol (TLP), see http://www.cisa.gov/tlp.

## Summary


**Description**


CISA obtained five malware samples - including artifacts related to SUBMARINE, SKIPJACK, SEASPRAY, WHIRLPOOL, and
SALTWATER backdoors. The device was compromised by threat actors exploiting CVE-2023-2868, a former zero-day vulnerability
affecting versions 5.1.3.001-9.2.0.006 of Barracuda Email Security Gateway (ESG).

For information about related malware, specifically information on the initial exploit payload, SEASPY backdoor, WHIRLPOOL
backdoor, and the SUBMARINE backdoor, see CISA Alert: CISA Releases Malware Analysis Reports on Barracuda Backdoors.


**Submitted Files (5)**


4183edae732506a18b5c802cbf0a471a77c3f1e4336a32ccb4958671e404493c (machineecho_-n_Y2htb2QgK3ggL3J...)

44e1fbe71c9fcf9881230cb924987e0e615a7504c3c04d44ae157f07405e3598 (mod_sender.lua)

63788797919985d0e567cf9133ad2ab7a1c415e81598dc07c0bfa3a1566aeb90 (get_fs_info.pl)

9f04525835f998d454ed68cfc7fcb6b0907f2130ae6c6ab7495d41aa36ad8ccf (saslautchd)

caab341a35badbc65046bd02efa9ad2fe2671eb80ece0f2fa9cf70f5d7f4bedc (mod_rft.so)

## Findings

**4183edae732506a18b5c802cbf0a471a77c3f1e4336a32ccb4958671e404493c**


**Details**


**Name** machineecho_-n_Y2htb2QgK3ggL3Jvb3QvbWFjKgpzaCAvcm9vdC9tYWNoKlxgKgoK___base64_-d__sh_-slack

**Size** 3894 bytes

**Type** data

**MD5** 9fdc1dc99bc8184ee410880427dba89c

**SHA1** be570775552f937d8588bceb3e2cbb0c18408fc1

**SHA256** 4183edae732506a18b5c802cbf0a471a77c3f1e4336a32ccb4958671e404493c

**SHA512** 2bb94fdfe31a464c63b8cd726f6ba1c3b18da538221d5bae943dfb03ec353a41826bdcb007bc2b7dfeb76afe619aa8ce0
78808e9b30079a6f947cce8ace891ff
**ssdeep** 3::

**Entropy** 0.000000


-----

**Antivirus**


No matches found.


**YARA Rules**


No matches found.


**ssdeep Matches**


No matches found.


**Description**


This file is a SUBMARINE artifact, an empty text/data file. The name of the file is designed to exploit a vulnerability on the target
environment where the base64 string within the file name will be executed on the Linux shell. The code in Figure 1 will change the
permissions of any directory/file/path with that begins with '/root/mac' to executable. Then, anything containing the string 'mach*' in
the directory/file/path '/root/mach' are executed.


**Screenshots**


**Figure 1 - Figure 1 depicts the Base64 encoded, and decoded, name of the artifact.**

**63788797919985d0e567cf9133ad2ab7a1c415e81598dc07c0bfa3a1566aeb90**


**Details**


**Name** get_fs_info.pl

**Size** 530 bytes

**Type** Perl script text executable

**MD5** ad1dc51a66201689d442499f70b78dea

**SHA1** c71bccdc006cca700257a69ed227e0cb1bc071ed

**SHA256** 63788797919985d0e567cf9133ad2ab7a1c415e81598dc07c0bfa3a1566aeb90

**SHA512** 3258af057858ef0930a48771869871736bfb866ef740e81f2518c0d4c217b5c0c5f8eb06985b72a3762ce011458245940
be6bb1d4907d2ed0f4e18886bbc48c3
**ssdeep** 12:HA4SKFBMygPZr7NBiC+c6jaY7PCbozFJG:thFBMZr7NBazjTzCbozG

**Entropy** 4.638131


**Antivirus**


No matches found.


**YARA Rules**



- rule CISA_10454006_11 : trojan

{
meta:
author = "CISA Code & Media Analysis"


-----

incident = "10454006"
date = "2023-07-20"
last_modified = "20230726_1700"
actor = "n/a"
family = "n/a"
Capabilities = "n/a"
Malware_Type = "trojan"
Tool_Type = "unknown"
description = "Detects perl script linked to SKIPJACK backdoor samples"
SHA256 = "63788797919985d0e567cf9133ad2ab7a1c415e81598dc07c0bfa3a1566aeb90"
strings:
$s1 = { 2f 65 74 63 2f 66 73 74 61 62 2e 6d 61 69 6e }
$s2 = { 28 3c 46 53 54 41 42 3e 29 }
$s3 = { 6d 79 20 28 24 70 61 72 74 69 74 69 6f 6e 2c 20 24 66 73 5f 74 79 70 65 29 }
$s4 = { 70 72 69 6e 74 20 24 66 73 5f 74 79 70 65 }
$s5 = { 70 72 69 6e 74 20 24 70 61 72 74 69 74 69 6f 6e }
condition:
all of them
}

**ssdeep Matches**

No matches found.


**Description**


This artifact, belonging to the SKIPJACK malware family, is a Perl script that enumerates file system information. This script first
checks the file system by opening '/etc/fstab.main/,' then checks the value against the array 'ARGV[0]', which perl automatically
provides to hold all values from the command line in. The script will print either 'xfs' or hda depending on the type of file system it
finds. The script contains a second if statement that gathers more information about the type of file system. This second if
statement contains the regular expression '/^\/dev\/(\S+)\d+\s+\/\s+(\S+)/,' which translates to '/etc/fstab.' The script uses this
second half of the code to check for file system type or information about the partition, which it then prints based on the value of
'$requested_data.'


**Screenshots**


-----

**Figure 2 - Figure 2 depicts code contained in "get_fs_info.pl."**

**44e1fbe71c9fcf9881230cb924987e0e615a7504c3c04d44ae157f07405e3598**


**Details**


**Name** mod_sender.lua

**Size** 3930 bytes

**Type** ASCII text

**MD5** 666da297066a2596cacb13b3da9572bf

**SHA1** 64b337d7e82c82a4b40c8cb88fbc651929995eef

**SHA256** 44e1fbe71c9fcf9881230cb924987e0e615a7504c3c04d44ae157f07405e3598

**SHA512** 4881a79d95bf83190be1542d7b26c7b1dee5eece1a689dc81bf2b661b43b3d724703dc4a48f824d8d960e2a480bcbea
2e4007eb19023ee1bf329d993009deffc
**ssdeep** 96:JnJKszX3Z+p351GUw5FbsNmnwdx8sMEFoiKe3:JnJjzZ+j14FIEnqxjMEKQ

**Entropy** 5.041616


**Antivirus**


No matches found.


**YARA Rules**



- rule CISA_10454006_12 : SEASPRAY trojan evades_av

{
meta:


-----

author = "CISA Code & Media Analysis"
incident = "10454006"
date = "2023-08-23"
last_modified = "20230905_1500"
actor = "n/a"
family = "SEASPRAY"
capabilities = "evades-av"
malware_type = "trojan"
tool_type = "unknown"
description = "Detects SEASPRAY samples"
sha256 = "44e1fbe71c9fcf9881230cb924987e0e615a7504c3c04d44ae157f07405e3598"
strings:
$s1 = { 6f 73 2e 65 78 65 63 75 74 65 28 27 73 61 73 6c 61 75 74 63 68 64 27 }
$s2 = { 73 65 6e 64 65 72 }
$s3 = { 73 74 72 69 6e 67 2e 66 69 6e 64 }
$s4 = { 73 74 72 69 6e 67 2e 6c 6f 77 65 72 }
$s5 = { 62 6c 6f 63 6b 2f 61 63 63 65 70 74 }
$s6 = { 72 65 74 75 72 6e 20 41 63 74 69 6f 6e 2e 6e 65 77 7b }
$s7 = { 4c 69 73 74 65 6e 65 72 2e 6e 65 77 7b }
condition:
filesize < 10KB and all of them
}


**ssdeep Matches**


No matches found.


**Relationships**


9f04525835f998d454ed68cfc7fcb6b0907f213
44e1fbe71c... Used
0ae6c6ab7495d41aa36ad8ccf


**Description**


This artifact is a trojanized Lua module that has been identified as a "SEASPRAY" variant. SEASPRAY registers an event handler
for all incoming email attachments. This variant checks for the sender and the string “obt”, which is hard coded in the lua file. If that
string is found the malware uses os.execute to execute the file “saslautchd”, see Figure 3.


**Screenshots**


**Figure 3 - This screenshot illustrates how the SEASPRAY filters traffic looking for the string "obt". Once that string is received**
SEASPRAY uses os.execute to execute the file "saslautchd".

**9f04525835f998d454ed68cfc7fcb6b0907f2130ae6c6ab7495d41aa36ad8ccf**


**Tags**


trojan


**Details**


**Name** saslautchd

**Size** 5034648 bytes

**Type** ELF 64-bit LSB executable, x86-64, version 1 (GNU/Linux), statically linked,
BuildID[sha1]=913db6f2f3c21bcb11e0fd02e2b88908b15b5c2d, for GNU/Linux 3.2.0, stripped
**MD5** 436587bad5e061a7e594f9971d89c468


-----

**SHA1** cf22082532d4d6387ea1c9bc4dc5b255aa7a0290

**SHA256** 9f04525835f998d454ed68cfc7fcb6b0907f2130ae6c6ab7495d41aa36ad8ccf

**SHA512** 825ba4c46f1f9c5a4f2ab3ccfd8e3ec02f50f749776df783a085aff89cb19ed983b07ecd0703c74a0474bec56e918ada00
2b683dec1228f18181a91b0b339234
**ssdeep** 98304:J8sPi2iUKJYO0OAgikIn9FCJM+rXKZ9ldvVkhyfMuG9vU:xVUildN0uX

**Entropy** 6.384586


**Antivirus**


**Antiy** Trojan/Linux.SAgnt

**Avira** LINUX/Whirlpool.A

**Bitdefender** Trojan.Generic.34035237

**Emsisoft** Trojan.Generic.34035237 (B)

**ESET** Linux/WhirlPool.A trojan

**McAfee** Generic trojan.xj

**Sophos** Linux/Agnt-BS

**Varist** E64/Agent.FP


**YARA Rules**



- rule CISA_10452108_02 : WHIRLPOOL backdoor communicates_with_c2 installs_other_components

{
meta:
author = "CISA Code & Media Analysis"
incident = "10452108"
date = "2023-06-20"
last_modified = "20230804_1730"
actor = "n/a"
family = "WHIRLPOOL"
Capabilities = "communicates-with-c2 installs-other-components"
Malware_Type = "backdoor"
Tool_Type = "unknown"
description = "Detects malicious Linux WHIRLPOOL samples"
sha256_1 = "83ca636253fd1eb898b244855838e2281f257bbe8ead428b69528fc50b60ae9c"
sha256_2 = "8849a3273e0362c45b4928375d196714224ec22cb1d2df5d029bf57349860347"
strings:
$s0 = { 65 72 72 6f 72 20 2d 31 20 65 78 69 74 }
$s1 = { 63 72 65 61 74 65 20 73 6f 63 6b 65 74 20 65 72 72 6f 72 3a 20 25 73 28 65 72 72 6f 72 3a 20 25 64 29 }
$s2 = { c7 00 20 32 3e 26 66 c7 40 04 31 00 }
$a3 = { 70 6c 61 69 6e 5f 63 6f 6e 6e 65 63 74 }
$a4 = { 63 6f 6e 6e 65 63 74 20 65 72 72 6f 72 3a 20 25 73 28 65 72 72 6f 72 3a 20 25 64 29 }
$a5 = { 73 73 6c 5f 63 6f 6e 6e 65 63 74 }
condition:
uint32(0) == 0x464c457f and 4 of them
}

**ssdeep Matches**

No matches found.


**Relationships**


44e1fbe71c9fcf9881230cb924987e0e615a75
9f04525835... Used_By
04c3c04d44ae157f07405e3598


**Description**


This artifact, belonging to the WHIRLPOOL malware family, is a 64-bit Linux Executable and Linkable Format (ELF) file. The
malware checks processor hardware and architecture, to include if the target system uses AMD or Intel, see Figure 4. Figure 5
shows the malware determining the kernel version by invoking the 'uname' command line function and exploring the contents of the


-----

'/proc/sys/kernel/osrelease' file. Figures 6, 7, and 8 show the malware's capacity to connect to a remote address, and then create a
new process with the command line argument '/bin/sh.' The connection to a remote host and the invocation of a bash shell are the
two components/phases used by reverse shells. Figure 9 shows the malware's capacity to interact with the Name Service Cache
Daemon by creating and connecting to a Unix socket at ./var/run/nscd/socket.' This socket can cache Domain Name System (DNS)
requests. Rather than listening on port 53, it listens on the socket file itself, for data from other programs/processes. Figure 10
shows the malware's capacity to perform DNS resolution, using the system call 'sys_getpeername.' The malware accesses the
target's environment variables. See below list below:

--Begin Accessed Environment Variables-GCONV_PATH
GETCONF_DIR
HTTPS_PROXY
HTTP_PROXY
LANG
LANGUAGE
LC_ALL
LC_COLLATE
LD_WARN
LD_LIBRARY_PATH
LD_BIND_NOW
LD_BIND_NOT
LD_DYNAMIC_WEAK
LD_PROFILE_OUTPUT
LD_ASSUME_KERNEL
LOCALDOMAIN
NO_PROXY
OPENSSL_CONF
OPENSSL_ia32cap
OUTPUT_CHARSET
POSIX
TZ
TZDIR
RESOLV_ADD_TRIM_DOMAINS
RESOLV_HOST_CONF
RESOLV_MULTI
RESOLV_OVERRIDE_TRIM_DOMAINS
RES_OPTIONS
RESOLV_REORDER
--End Accessed Environment Variables-
The malware further access the following files at runtime:

--Begin Accessed Files-/etc/aliases
/etc/ethers
/etc/group
/etc/hosts
/etc/networks
/etc/protocols
/etc/passwd
/etc/rpc
/etc/services
/etc/gshadow
/etc/shadow
/etc/netgroup
/dev/full
/dev/urandom
/dev/random
/proc/sys/kernel/rtsig/proc/sys/kernel/ngroups_max
/sys/devices/system/cpu/online
/proc/stat
/proc/self/fd


-----

-- End Accessed Files-

**Screenshots**


**Figure 4 - Figure 4 depicts the use of the 'cpuid' assembly instruction and strings amalgamating to 'intel' and 'AMD.'**

**Figure 5 - Figure 5 depicts the 'uname' Linux OS command line function. This figure further depicts a call to functions that open**
and read the contents of the path '/proc/sys/kernel/osrelease/.'

**Figure 6 - Figure 6 depicts the creation of a socket that facilitates Internet Protocol Version 4 connections. It further depicts a**
connection to a remote address using the 'sys_connect' function.


-----

**Figure 7 - Figure 7 depicts the string 'sh -c /bin/sh' fed into the 'sys_execve' function as an argument.**

**Figure 8 - Figure 8 depicts the string 'sh -c /bin/sh' fed into the 'sys_execve' function as an argument.**


-----

**Figure 9 - Figure 9 shows the malware's ability to interact with the Name Service Cache Daemon.**

**Figure 10 - Figure 10 depicts the Linux OS system call, 'sys_getpeername.'**

**caab341a35badbc65046bd02efa9ad2fe2671eb80ece0f2fa9cf70f5d7f4bedc**


**Tags**


trojan


**Details**


**Name** mod_rft.so

**Size** 1668232 bytes

**Type** ELF 32-bit LSB shared object, Intel 80386, version 1 (SYSV), dynamically linked, stripped

**MD5** 4ec4ceda84c580054f191caa09916c68

**SHA1** 6505513ca06db10b17f6d4792c30a53733309231

**SHA256** caab341a35badbc65046bd02efa9ad2fe2671eb80ece0f2fa9cf70f5d7f4bedc

**SHA512** c61493cfa3c6c41520b6ef608da9398b4fa6a7805293bc98d628335f536509d95585d42f93b8edeabf971390e874c5291
b552afe66d72651839a295b76c42380
**ssdeep** 24576:25gY/a9MQrLO457KIRTQvAunkEKkb8EHA4pje0ET1Nyb+YpYcNvwoQItHzUMDb:25b8y45V2IVEHASjezfYH
woDzUM
**Entropy** 6.211061


**Antivirus**


**AhnLab** Malware/Linux.Agent

**Antiy** Trojan/Linux.SaltWater.b

**Bitdefender** Trojan.Linux.Generic.313776

**Emsisoft** Trojan.Linux.Generic.313776 (B)

**ESET** a variant of Linux/SaltWater.B trojan

**McAfee** Generic trojan.xj

**Quick Heal** ELF.WhirlPool.48041.GC

**Sophos** Linux/Agnt-BS


**YARA Rules**



- rule CISA_10454006_13 : SALTWATER backdoor exploit_kit communicates_with_c2 determines_c2_server

hides_executing_code exploitation
{
meta:
author = "CISA Code & Media Analysis"
incident = "10454006"
date = "2023-08-10"
last_modified = "20230905_1500"
actor = "n/a"
family = "SALTWATER"
capabilities = "communicates-with-c2 determines-c2-server hides-executing-code"
malware_type = "backdoor exploit-kit"
tool_type = "exploitation"


-----

description = "Detects SALTWATER samples"
sha256 = "caab341a35badbc65046bd02efa9ad2fe2671eb80ece0f2fa9cf70f5d7f4bedc"
strings:
$s1 = { 70 74 68 72 65 61 64 5f 63 72 65 61 74 65 }
$s2 = { 67 65 74 68 6f 73 74 62 79 6e 61 6d 65 }
$s3 = { 54 72 61 6d 70 6f 6c 69 6e 65 }
$s4 = { 64 73 65 6c 64 73 }
$s5 = { 25 30 38 78 20 28 25 30 32 64 29 20 25 2d 32 34 73 20 25 73 25 73 25 73 0a }
$s6 = { 45 6e 74 65 72 20 6f 75 73 63 64 6f 6f 65 7c 70 72 65 64 61 72 65 28 25 70 2c 20 25 70 2c 20 25 70 29 }
$s7 = { 45 6e 74 65 72 20 61 75 74 63 63 6f 6f 71 38 63 72 65 61 74 65 }
$s8 = { 74 6e 6f 72 6f 74 65 63 74 6a 73 65 6d 6f 72 79 }
$s9 = { 56 55 43 4f 4d 49 53 53 }
$s10 = { 56 43 4f 4d 49 53 53 }
$s11 = { 55 43 4f 4d 49 53 44 }
$s12 = { 41 45 53 4b 45 59 47 45 4e 41 53 53 49 53 54 }
$s13 = { 46 55 43 4f 4d 50 50 }
$s14 = { 55 43 4f 4d 49 53 53 }
condition:
uint16(0) == 0x457f and filesize < 1800KB and 8 of them
}

**ssdeep Matches**

No matches found.


**Description**


This artifact, belonging to the SALTWATER malware family, is a 32-bit Linux Shared Object (.so) file. The malware can intake data
over the network, using a previously established socket, with the 'recv' function as shown in Figure 11. Figure 12 shows the
malware creating a new thread, within the calling process. This is thread injection and it can inject two different functions. Figure 13
shows the first function that can perform DNS resolution. Figures 14 and 15 show the second function. The second function can
establish communications, over the network, using a TLS version 1 connection. Lastly, using 'popen', the malware can execute any
shell command with the same privileges as its calling process.


**Screenshots**


**Figure 11 - Figure 11 depicts the 'recv' Berkeley Sockets function dynamically loaded and executed at runtime.**

**Figure 12 - Figure 12 depicts the 'pthread_create' function.**


-----

**Figure 13 - Figure 13 depicts multiple functions from the Berkley Sockets API.**

**Figure 14 - Figure 14 depicts functions that facilitate Secure Sockets Layer (SSL) and TLS communications.**


-----

**Figure 15 - Figure 15 depicts the 'popen' function.**

## Relationship Summary

9f04525835f998d454ed68cfc7fcb6b0907f213
44e1fbe71c... Used
0ae6c6ab7495d41aa36ad8ccf

44e1fbe71c9fcf9881230cb924987e0e615a75
9f04525835... Used_By
04c3c04d44ae157f07405e3598

## Recommendations

CISA recommends that users and administrators consider using the following best practices to strengthen the security posture of
their organization's systems. Any configuration changes should be reviewed by system owners and administrators prior to
implementation to avoid unwanted impacts.

 - Maintain up-to-date antivirus signatures and engines.

 - Keep operating system patches up-to-date.

 - Disable File and Printer sharing services. If these services are required, use strong passwords or Active Directory authentication.

 - Restrict users' ability (permissions) to install and run unwanted software applications. Do not add users to the local administrators

group unless required.

 - Enforce a strong password policy and implement regular password changes.

 - Exercise caution when opening e-mail attachments even if the attachment is expected and the sender appears to be known.

 - Enable a personal firewall on agency workstations, configured to deny unsolicited connection requests.

 - Disable unnecessary services on agency workstations and servers.

 - Scan for and remove suspicious e-mail attachments; ensure the scanned attachment is its "true file type" (i.e., the extension

matches the file header).

 - Monitor users' web browsing habits; restrict access to sites with unfavorable content.

 - Exercise caution when using removable media (e.g., USB thumb drives, external drives, CDs, etc.).

 - Scan all software downloaded from the Internet prior to executing.

 - Maintain situational awareness of the latest threats and implement appropriate Access Control Lists (ACLs).

Additional information on malware incident prevention and handling can be found in National Institute of Standards and Technology
(NIST) Special Publication 800-83, "Guide to Malware Incident Prevention & Handling for Desktops and Laptops".

## Contact Information

 - 1-888-282-0870

[• CISA Service Desk (UNCLASS)](mailto:CISAservicedesk@cisa.dhs.gov)

[• CISA SIPR (SIPRNET)](mailto:NCCIC@dhs.sgov.gov)


-----

[• CISA IC (JWICS)](mailto:NCCIC@dhs.ic.gov)

CISA continuously strives to improve its products and services. You can help by answering a very short series of questions about
[this product at the following URL: https://us-cert.cisa.gov/forms/feedback/](https://us-cert.cisa.gov/forms/feedback/)

## Document FAQ

**What is a MIFR? A Malware Initial Findings Report (MIFR) is intended to provide organizations with malware analysis in a timely**
manner. In most instances this report will provide initial indicators for computer and network defense. To request additional analysis,
please contact CISA and provide information regarding the level of desired analysis.

**What is a MAR? A Malware Analysis Report (MAR) is intended to provide organizations with more detailed malware analysis**
acquired via manual reverse engineering. To request additional analysis, please contact CISA and provide information regarding
the level of desired analysis.

**Can I edit this document? This document is not to be edited in any way by recipients. All comments or questions related to this**
[document should be directed to the CISA at 1-888-282-0870 or CISA Service Desk.](mailto:CISAservicedesk@cisa.dhs.gov)

**Can I submit malware to CISA? Malware samples can be submitted via three methods:**

[• Web: https://malware.us-cert.gov](https://malware.us-cert.gov/)

[• E-Mail: submit@malware.us-cert.gov](mailto:submit@malware.us-cert.gov)

 - FTP: ftp.malware.us-cert.gov (anonymous)

CISA encourages you to report any suspicious activity, including cybersecurity incidents, possible malicious code, software
[vulnerabilities, and phishing-related scams. Reporting forms can be found on CISA's homepage at www.cisa.gov.](http://www.cisa.gov/)


## TLP: CLEAR


-----