Main description

QakBot, also known as QBot, QuackBot and Pinkslipbot, is a banking Trojan that has existed for over a decade. It was found in the wild in 2007 and since then it has been continually maintained and developed.

In recent years, QakBot has become one of the leading banking Trojans around the globe. Its main purpose is to steal banking credentials( e.g ., logins, passwords, etc .), though it has also acquired functionality enable it to spy on financial operations, spread itself, and install ransomware in order to maximize revenue from compromised organizations.

To this day, QakBot continues to grow in terms of functionality, with even more capabilities and new techniques such as logging keystrokes, a backdoor functionality, and techniques to escape detecting. It’s worth mentioning that the latter includes virtual environment detection, regular self-updates and cryptor/ packer alterations. In addition, QakBot tries to protect itself from being analyzed and debugged by experts and automated tools.

Another interesting piece of functionality is the ability to steal emails. These are later used by the attackers to send targeted emails to the victims, with the obtained information being used to lure victims into opening those emails.

QakBot infection chain

QakBot is known to infect its victims mainly via spam campaigns. In some suits, the emails was handed over with Microsoft Office documents( Word, Excel) or password-protected archives with the above-mentioned documents attached. The above-mentioned documents contained macros and victims were prompted to open the attachments with claims that they contained important information( e.g ., an invoice ). In some occurrences, the emails contained links to web pages distributing malicious documents.

However, there is another infection vector that involves a malicious QakBot payload being transferred to the victim’s machine via other malware on the compromised machine.

The initial infection vectors may vary depending on what security threats performers belief has the best chance of success for the targeted organization( s ). It’s known that various threat performers perform reconnaissance( OSINT) of target organizations beforehand to decide which infection vector is most suitable.

QakBot infection chain

QakBot infection chain

The infection chain of recent QakBot releases( 2020 -2 021 variants) is as follows 😛 TAGEND

The user receives a phishing email with a ZIP attachment containing an Office document with embedded macros, the document itself or a link to download malicious document. The customer opens the malicious attachment/ relate and is tricked into clicking” Enable content “. A malicious macro is executed. Some variants perform a’ GET’ request to a URL requesting a’ PNG’ However, the file is in fact a binary. The loaded warhead( stager) includes another binary containing encrypted resource modules. One of the encrypted resources has the DLL binary( loader) which is decrypted later during runtime. The’ Stager’ loadings the’ Loader’ into the memory, which decrypts and runs the payload during runtime. The configuration settings are recovered from another resource. The payload communicates with the C2 server. Additional menaces such as ProLock ransomware can now be pushed to the infected machine.

Typical QakBot roles

Typical QakBot malicious activity observed in the wild includes 😛 TAGEND

Collecting information about the compromised host; Creating scheduled duties( privilege escalation and persistency ); Credentials harvesting:

Credential dumping( Mimikatz, exe access) *; Password stealing( from browser data and cookies ); Targeting web banking links( web injects) *.

Password brute coerce; Registry manipulation( persistence ); Creating a photocopy of itself; Process injection to conceal the malicious process.

Communication with C2

The QakBot malware contains a list of 150 IP addresses hardcoded into the loader binary resource. Most of these addresses is a matter for other infected systems that are used as a proxy to forward traffic to other proxies or the real S2.

Communication with the S2 is a HTTPS POST request with Base6 4-encoded data. The data is encrypted with the RC4 algorithm. The static string “jHxastDcds)oMc=jvh7wdUhxcsdt2” and a random 16 -byte sequence are used for encryption. The data itself is in JSON format.

Original message in JSON format

Original message in JSON format

HTTPS POST request with encrypted JSON

HTTPS POST request with encrypted JSON

Usually, after infection the bot sends a’ PING’ message,’ SYSTEM INFO’ message and’ ASK for COMMAND’ message, and the C2 replies with’ ACK’ and’ COMMAND’ messages. If additional modules were pushed by the C2, the bot sends a’ STOLEN INFO’ message containing data stolen by the modules.

‘ PING’ message- bot petition message to C2 with’ BOT ID’ in order to verify if S2 is active:

'PING' message

‘PING’ message

‘ ACK’ message- C2 response message with battleground “16” containing the external IP address of the infected system, the only valuable information:

'ACK' message

‘ACK’ message

SYSTEM INFO’ message- bot petition message to C2 with info collected about the infected system. In addition to general system knowledge such as OS version and bitness, customer name, computer name, realm, screen resolution, system day, system uptime and bot uptime, it also contains the results of the following utilities and WMI queries:

whoami/ all arp -a ipconfig/ all net view/ all cmd/ c determined nslookup -querytype= ALL -timeout= 10 _ldap._tcp.dc._msdcs . DOMAIN nltest/ domain_trusts/ all_trusts net share route publish netstat -nao net localgroup qwinsta WMI Query ROOT \ CIMV2: Win3 2_BIOS WMI Query ROOT \ CIMV2: Win3 2_DiskDrive WMI Query ROOT \ CIMV2: Win3 2_PhysicalMemory WMI Query ROOT \ CIMV2: Win3 2_Product WMI Query ROOT \ CIMV2: Win3 2_PnPEntity

'SYSTEM INFO' message

SYSTEM INFO’ message

‘ ASK for COMMAND’ message- bot command petition message to C2. After the’ SYSTEM INFO’ message is mailed, the bot starts asking the C2 for a command to execute. One of the main fields is “14”- the SALT. This battleground is unique and changes in every request. It is used to protect against hijacking or takeover of a bot. After receiving this petition, the S2 uses the SALT in the signing procedure and places the signature in the response, so the bot can check the signed data. Simply a valid and signed command will be executed.

'ASK for COMMAND' message

‘ASK for COMMAND’ message

‘ COMMAND’ message- C2 response message with command to execute. The current version of the bot supportings 24 commands, most of them related to download, executing, drop-off of additional modules and module configuration files with different options, or setup/ update configuration values. This type of message contains the signed value of the SALT( obtained from the bot’s request field ” 14″ ), COMMAND ID and MODULE ID. The other values of the message are not signed.In previous versions, the bot received modules and commands immediately after infection and sending a’ SYSTEM INFO’ message. Now, the C2 reacts with an empty command for about an hour. Merely after that will the C2 send commands and modules in the response. We believe that this time delay is used to make it difficult to receive and analyze new commands and modules in an isolated controlled environment.

'COMMAND' C2 response with empty command

‘COMMAND’ C2 response with empty command

If the C2 pushes some modules, the Base6 4-encoded binary is placed into field “20” of the message.

'COMMAND' C2 response with additional module to load

‘COMMAND’ C2 response with additional module to load

‘ STOLEN INFO’ message- bot message to C2 with stolen datum like passwords, accounts, emails, etc. Stolen information is RC4 encrypted and Base6 4 encoded. The key for the RC4 encryption is generated in a different way and based on the infected system ID( aka Bot ID) values, and not based on a static string such as in the case of traffic encryption.

'STOLEN INFO' message

‘STOLEN INFO’ message

Once communication with the C2 server has been established, QakBot is known to download and use additional modules in order to perform its malicious operations.

The additional modules differ from sample to sample and may include:’ Cookie grabber ‘,’ Email Collector ‘,’ Credentials grabber ‘, and’ Proxy module’ among others.

These modules may be written by the threat actors themselves or may be borrowed from third-party repositories and accommodated. It can differ from sample to sample. For example, there are older samples that may use Mimikatz for credentials dumping.

Below are some of the modules that we saw during our research.

Additional modules

Cookie Grabber- accumulates cookies from popular browsers( Edge, Firefox, Chrome, Internet Explorer ).

Hidden VNC- permits menace actors to connect to the infected machine and interact with it without the real user knowing.

Email Collector- tries to find Microsoft Outlook on the infected machine, then iterates over the software folders and recursively accumulates emails. Eventually, the module exfiltrates the compiled emails to the remote server.

The threat actors distributed a debug version of the email collector module at some point

The threat performers distributed a debug version of the email collector module at some point

Hooking module- hooks a hardcoded determine of WinAPI and( if they exist) Mozilla DLL Hooking is used to perform web injects, sniff traffic and keyboard data and even avoid DNS resolution of certain domains. Hooking works in the following way: QakBot injects a hooking module into the appropriate process, the module acquires parts from the hardcoded fixed and modifies the functions so they hop to custom code.

The module contains a ciphered list of DLLs and functions that the bot will hook

The module contains a ciphered list of DLLs and functions that the bot will hook

Passgrabber module- accumulates logins and passwords from various sources: Firefox and Chrome files, Microsoft Vault storage, etc. Instead of using Mimikatz as in previous versions, the module collects passwords employing its own algorithms.

Procedure that collects passwords from different sources

Procedure that compiles passwords from different sources

Proxy module- tries to determine which ports are available to listen to using the UPnP port forwarding and tier 2 S2 query. Comparing current and old proxy loader versions exposed some interesting things: the threat performers decided to remove the cURL dependency from the binary and perform all HTTP communications using their own code. Besides removing cURL, they likewise removed OpenSSL dependencies and embedded all functions into a single executable- there are no more proxy loaders or proxy modules, it’s a single file now.

UPnP port forwarding query construction

UPnP port forwarding query construction

After trying to determine whether ports are open and the machine could act as a C2 tier 2 proxy, the proxy module likewise starts a multithreaded SOCKS5 proxy server. The SOCKS5 protocol is encapsulated into the QakBot proxy protocol composed of: QakBot proxy command( 1 byte ), version( 1 byte ), conference id( 4 bytes ), total packet length( dword ), data( total packet length-1 0 ). Incoming and outgoing packets are stored in the buffers and may be received/ transmitted one by one or in multiple packets in a single TCP data segment( streamed ).

The usual proxy module execution flowing is as follows 😛 TAGEND

Communicate with the C2, try to forward ports with UPnP and specify available ports and report them to the C2. The usual C2 communication protocol used here is HTTP POST RC4-ciphered JSON data. Download the OpenSSL library. Instead of saving the downloaded file, QakBot measures the download speed and deletes the received file. Determine up external PROXY-C2 connection that was received with command 37( update config )/ module 274( proxy) by the stager.

Communicating with the external PROXY-C2 😛 TAGEND

Send initial proxy module request. The initial request contains the bot ID, external IP address of the infected machine, overrule DNS lookup of the external IP address, internet hastened( measured earlier) and seconds since the proxy module started. Establish a linkage( proxy commands sequence 1-> 10 -> 11) with the PROXY-C2. Initialize sessions, perform socks5 authorization with login/ password( received from PROXY-C2 with command 10 ). Begin SOCKS5-like communication wrapped into the QakBot proxy module protocol.

QakBot proxy commands are as follows 😛 TAGEND

Command Description 1 Hello( bot-> C2)

10 Set up auth credentials( C2-> bot)

11 Show credentials setup( bot-> C2)

2 Make new proxy session( C2-> bot)

3 SOCKS5 AUTH( bot-> C2)

4 SOCKS5 requests processing( works for both sides)

5 Close conference( works for both sides)

6 Update conference nation/ conference government updated notification( works for both sides)

7 Update conference state/ session country updated notification( works for both sides)

8 PING( C2-> bot)

9 PONG( bot-> C2)

19 Save current time in registry( C2-> bot)

Parsed packets from C2

Parsed packets from C2

Tracking single proxy

Tracking single proxy

Web inject- the configuration file for the hooking module Once communication with the C2 is established, one of the additional modules that is downloaded is the web-inject module. It intercepts the victim’s traffic by injecting the module into the browser’s process and hooking the network API. The hooking module gets the execution flowing from intercepted APIs, and as soon as the main victims retrieves certain web pages related to banking and finance, additional JavaScript is injected into the source page.

Fragment of JavaScript injected into the source page of the Wells Fargo login page

Fragment of JavaScript injected into the source page of the Wells Fargo login page

QakBot statistics

We analyzed statistics on QakBot assaults collected from our Kaspersky Security Network( KSN ), where anonymized data voluntarily provided by Kaspersky consumers is accumulated and processed. In the first seven months of 2021 our products detected 181,869 attempts to download or run QakBot. This number be less than the detection number from January to July 2020, though the number of users affected grew by 65% compared to the previous year and reached 17,316.

Number of users affected by QakBot attempts from January to July in 2020 and 2021( download)

We observed the largest campaigns in Q1 2021 when 12,704 customers encountered QakBot, with 8,068 Kaspersky users being targeted in January and 4,007 in February.

Judgment

QakBot is a known Trojan-Banker whose techniques may vary from binary to binary( older and newer versions ). It has been active for over a decade and doesn’t look like going away anytime soon. The malware is continuously receiving updates and the threat actors keep adding new capabilities and updating its modules in order to steal information and maximize revenue.

We know that threat actors alter how they perform their malicious activities based on security vendor activities, employing sophisticated techniques to stay under the radar. Although QakBot employs different techniques to avoid detection, for example, process enumeration in order to find running anti-malware solutions, our products are able to detect the threat using behavior analysis. The judgments usually assigned to this malware 😛 TAGEND

Backdoor.Win3 2. QBot Backdoor.Win64.QBot Trojan.JS.QBot Trojan.MSOffice.QBot Trojan.MSOffice.QbotLoader Trojan.Win32.QBot Trojan-Banker.Win3 2. QBot Trojan-Banker.Win32.QakBot Trojan-Banker.Win6 4. QBot Trojan-Downloader.JS.QBot Trojan-PSW.Win3 2. QBot Trojan-Proxy.Win32.QBot

Indicators of compromise( C2 server addresses)

75.67.192 [.] 125:443 24.179.77[.]236:443 70.163.161 [.] 79:443

72.240.200 [.] 181:2222 184.185.103[.]157:443 78.63.226 [.] 32:443

83.196.56 [.] 65:2222 95.77.223[.]148:443 76.168.147 [.] 166:993

105.198.236 [.] 99:443 73.151.236[.]31:443 64.121.114 [.] 87:443

213.122.113 [.] 120:443 97.69.160[.]4:2222 77.27.207 [.] 217:995

105.198.236 [.] 101:443 75.188.35[.]168:443 31.4.242 [.] 233:995

144.139.47 [.] 206:443 173.21.10[.]71:2222 125.62.192 [.] 220:443

83.110.109 [.] 155:2222 76.25.142[.]196:443 195.12.154 [.] 8: 443

186.144.33 [.] 73:443 67.165.206[.]193:993 96.21.251 [.] 127:2222

149.28.98 [.] 196:2222 222.153.122[.]173:995 71.199.192 [.] 62:443

45.77.117 [.] 108:2222 45.46.53[.]140:2222 70.168.130 [.] 172:995

45.32.211 [.] 207:995 71.74.12[.]34:443 82.12.157 [.] 95:995

149.28.98 [.] 196:995 50.29.166[.]232:995 209.210.187 [.] 52:995

149.28.99 [.] 97:443 109.12.111[.]14:443 209.210.187 [.] 52:443

207.246.77 [.] 75:8443 68.186.192[.]69:443 67.6.12 [.] 4:443

149.28.99 [.] 97:2222 188.27.179[.]172:443 189.222.59 [.] 177:443

149.28.101 [.] 90:443 98.192.185[.]86:443 174.104.22 [.] 30:443

149.28.99 [.] 97:995 189.210.115[.]207:443 142.117.191 [.] 18:2222

149.28.101 [.] 90:8443 68.204.7[.]158:443 189.146.183 [.] 105:443

92.59.35 [.] 196:2222 75.137.47[.]174:443 213.60.147 [.] 140:443

45.63.107 [.] 192:995 24.229.150[.]54:995 196.221.207 [.] 137:995

45.63.107 [.] 192:443 86.220.60[.]247:2222 108.46.145 [.] 30:443

45.32.211 [.] 207:8443 193.248.221[.]184:2222 187.250.238 [.] 164:995

197.45.110 [.] 165:995 151.205.102[.]42:443 2.7.116 [.] 188:2222

45.32.211 [.] 207:2222 71.41.184[.]10:3389 195.43.173 [.] 70:443

96.253.46 [.] 210:443 24.55.112[.]61:443 106.250.150 [.] 98:443

172.78.59 [.] 180:443 24.139.72[.]117:443 45.67.231 [.] 247:443

90.65.234 [.] 26:2222 72.252.201[.]69:443 83.110.103 [.] 152:443

47.22.148 [.] 6:443 175.143.92[.]16:443 83.110.9 [.] 71:2222

149.28.101 [.] 90:995 100.2.20[.]137:443 78.97.207 [.] 104:443

207.246.77 [.] 75:2222 46.149.81[.]250:443 59.90.246 [.] 200:443

144.202.38 [.] 185:995 207.246.116[.]237:8443 80.227.5 [.] 69:443

45.77.115 [.] 208:995 207.246.116[.]237:995 125.63.101 [.] 62:443

149.28.101 [.] 90:2222 207.246.116[.]237:443 86.236.77 [.] 68:2222

45.32.211 [.] 207:443 207.246.116[.]237:2222 109.106.69 [.] 138:2222

149.28.98 [.] 196:443 45.63.107[.]192:2222 84.72.35 [.] 226:443

45.77.117 [.] 108:443 71.163.222[.]223:443 217.133.54 [.] 140:32100

144.202.38 [.] 185:2222 98.252.118[.]134:443 197.161.154 [.] 132:443

45.77.115 [.] 208:8443 96.37.113[.]36:993 89.137.211 [.] 239:995

45.77.115 [.] 208:443 27.223.92[.]142:995 74.222.204 [.] 82:995

207.246.77 [.] 75:995 24.152.219[.]253:995 122.148.156 [.] 131:995

45.77.117 [.] 108:8443 24.95.61[.]62:443 156.223.110 [.] 23:443

45.77.117 [.] 108:995 96.61.23[.]88:995 144.139.166 [.] 18:443

45.77.115 [.] 208:2222 92.96.3[.]180:2078 202.185.166 [.] 181:443

144.202.38 [.] 185:443 71.187.170[.]235:443 76.94.200 [.] 148:995

207.246.77 [.] 75:443 50.244.112[.]106:443 71.63.120 [.] 101:443

140.82.49 [.] 12:443 24.122.166[.]173:443 196.151.252 [.] 84:443

81.214.126 [.] 173:2222 73.25.124[.]140:2222 202.188.138 [.] 162:443

216.201.162 [.] 158:443 47.196.213[.]73:443 74.68.144 [.] 202:443

136.232.34 [.] 70:443 186.154.175[.]13:443 69.58.147 [.] 82:2078

* Can be performed as an external command( widened module ).

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