New AgentTesla variant steals WiFi credentials By Hossein Jazi Published: 2020-04-15 · Archived: 2026-04-06 01:03:42 UTC Popular stealer looking to expand Since AgentTesla added the WiFi-stealing feature, we believe the threat actors may be considering using WiFi as a mechanism for spread, similar to what was observed with Emotet. Another possibility is using the WiFi profile to set the stage for future attacks. Either way, Malwarebytes users were already protected from this new variant of AgentTesla through our real-time protection technology. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 1 of 44 Indicators of compromise AgentTesla samples: 91b711812867b39537a2cd81bb1ab10315ac321a1c68e316bf4fa84badbc09b dd4a43b0b8a68db65b00fad99519539e2a05a3892f03b869d58ee15fdf5aa044 27939b70928b285655c863fa26efded96bface9db46f35ba39d2a1295424c07b First payload: 249a503263717051d62a6d65a5040cf408517dd22f9021e5f8978a819b18063b Second payload:  63393b114ebe2e18d888d982c5ee11563a193d9da3083d84a611384bc748b1b0 https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 2 of 44 Note: If the final list has less than three elements, it won’t generate a SMTP message. If everything checks out, a message is finally sent via smtp.yandex.com, with SSL enabled (Figure 9): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 3 of 44 The following diagram shows the whole process explained above from extraction of first payload from the image resource to exfiltration of the stolen information over SMTP: Popular stealer looking to expand Since AgentTesla added the WiFi-stealing feature, we believe the threat actors may be considering using WiFi as a mechanism for spread, similar to what was observed with Emotet. Another possibility is using the WiFi profile to set the stage for future attacks. Either way, Malwarebytes users were already protected from this new variant of AgentTesla through our real-time protection technology. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 4 of 44 Indicators of compromise AgentTesla samples: 91b711812867b39537a2cd81bb1ab10315ac321a1c68e316bf4fa84badbc09b dd4a43b0b8a68db65b00fad99519539e2a05a3892f03b869d58ee15fdf5aa044 27939b70928b285655c863fa26efded96bface9db46f35ba39d2a1295424c07b First payload: 249a503263717051d62a6d65a5040cf408517dd22f9021e5f8978a819b18063b Second payload:  63393b114ebe2e18d888d982c5ee11563a193d9da3083d84a611384bc748b1b0 https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 5 of 44 Collected information forms the body section of a SMTP message in html format (Figure 8): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 6 of 44 Note: If the final list has less than three elements, it won’t generate a SMTP message. If everything checks out, a message is finally sent via smtp.yandex.com, with SSL enabled (Figure 9): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 7 of 44 The following diagram shows the whole process explained above from extraction of first payload from the image resource to exfiltration of the stolen information over SMTP: Popular stealer looking to expand Since AgentTesla added the WiFi-stealing feature, we believe the threat actors may be considering using WiFi as a mechanism for spread, similar to what was observed with Emotet. Another possibility is using the WiFi profile to set the stage for future attacks. Either way, Malwarebytes users were already protected from this new variant of AgentTesla through our real-time protection technology. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 8 of 44 Indicators of compromise AgentTesla samples: 91b711812867b39537a2cd81bb1ab10315ac321a1c68e316bf4fa84badbc09b dd4a43b0b8a68db65b00fad99519539e2a05a3892f03b869d58ee15fdf5aa044 27939b70928b285655c863fa26efded96bface9db46f35ba39d2a1295424c07b First payload: 249a503263717051d62a6d65a5040cf408517dd22f9021e5f8978a819b18063b Second payload:  63393b114ebe2e18d888d982c5ee11563a193d9da3083d84a611384bc748b1b0 https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 9 of 44 For example, in Figure 5, “119216” is decrypted into “wlan show profile name=” and “119196” is decrypted into “key=clear”. In addition to WiFi profiles, the executable collects extensive information about the system, including FTP clients, browsers, file downloaders, and machine info (username, computer name, OS name, CPU architecture, RAM) and adds them to a list (Figure 7). Collected information forms the body section of a SMTP message in html format (Figure 8): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 10 of 44 Note: If the final list has less than three elements, it won’t generate a SMTP message. If everything checks out, a message is finally sent via smtp.yandex.com, with SSL enabled (Figure 9): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 11 of 44 The following diagram shows the whole process explained above from extraction of first payload from the image resource to exfiltration of the stolen information over SMTP: Popular stealer looking to expand Since AgentTesla added the WiFi-stealing feature, we believe the threat actors may be considering using WiFi as a mechanism for spread, similar to what was observed with Emotet. Another possibility is using the WiFi profile to set the stage for future attacks. Either way, Malwarebytes users were already protected from this new variant of AgentTesla through our real-time protection technology. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 12 of 44 Indicators of compromise AgentTesla samples: 91b711812867b39537a2cd81bb1ab10315ac321a1c68e316bf4fa84badbc09b dd4a43b0b8a68db65b00fad99519539e2a05a3892f03b869d58ee15fdf5aa044 27939b70928b285655c863fa26efded96bface9db46f35ba39d2a1295424c07b First payload: 249a503263717051d62a6d65a5040cf408517dd22f9021e5f8978a819b18063b Second payload:  63393b114ebe2e18d888d982c5ee11563a193d9da3083d84a611384bc748b1b0 String encryption All the strings used by the malware are encrypted and are decrypted by Rijndael symmetric encryption algorithm in the “.u200E” function. This function receives a number as an input and generates three byte arrays containing input to be decrypted, key and IV (Figure 6). https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 13 of 44 For example, in Figure 5, “119216” is decrypted into “wlan show profile name=” and “119196” is decrypted into “key=clear”. In addition to WiFi profiles, the executable collects extensive information about the system, including FTP clients, browsers, file downloaders, and machine info (username, computer name, OS name, CPU architecture, RAM) and adds them to a list (Figure 7). Collected information forms the body section of a SMTP message in html format (Figure 8): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 14 of 44 Note: If the final list has less than three elements, it won’t generate a SMTP message. If everything checks out, a message is finally sent via smtp.yandex.com, with SSL enabled (Figure 9): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 15 of 44 The following diagram shows the whole process explained above from extraction of first payload from the image resource to exfiltration of the stolen information over SMTP: Popular stealer looking to expand Since AgentTesla added the WiFi-stealing feature, we believe the threat actors may be considering using WiFi as a mechanism for spread, similar to what was observed with Emotet. Another possibility is using the WiFi profile to set the stage for future attacks. Either way, Malwarebytes users were already protected from this new variant of AgentTesla through our real-time protection technology. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 16 of 44 Indicators of compromise AgentTesla samples: 91b711812867b39537a2cd81bb1ab10315ac321a1c68e316bf4fa84badbc09b dd4a43b0b8a68db65b00fad99519539e2a05a3892f03b869d58ee15fdf5aa044 27939b70928b285655c863fa26efded96bface9db46f35ba39d2a1295424c07b First payload: 249a503263717051d62a6d65a5040cf408517dd22f9021e5f8978a819b18063b Second payload:  63393b114ebe2e18d888d982c5ee11563a193d9da3083d84a611384bc748b1b0 https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 17 of 44 In the next step for each wireless profile, the following command is executed to extract the profile’s credential: “netsh wlan show profile PRPFILENAME key=clear” (Figure 5). String encryption All the strings used by the malware are encrypted and are decrypted by Rijndael symmetric encryption algorithm in the “.u200E” function. This function receives a number as an input and generates three byte arrays containing input to be decrypted, key and IV (Figure 6). https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 18 of 44 For example, in Figure 5, “119216” is decrypted into “wlan show profile name=” and “119196” is decrypted into “key=clear”. In addition to WiFi profiles, the executable collects extensive information about the system, including FTP clients, browsers, file downloaders, and machine info (username, computer name, OS name, CPU architecture, RAM) and adds them to a list (Figure 7). Collected information forms the body section of a SMTP message in html format (Figure 8): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 19 of 44 Note: If the final list has less than three elements, it won’t generate a SMTP message. If everything checks out, a message is finally sent via smtp.yandex.com, with SSL enabled (Figure 9): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 20 of 44 The following diagram shows the whole process explained above from extraction of first payload from the image resource to exfiltration of the stolen information over SMTP: Popular stealer looking to expand Since AgentTesla added the WiFi-stealing feature, we believe the threat actors may be considering using WiFi as a mechanism for spread, similar to what was observed with Emotet. Another possibility is using the WiFi profile to set the stage for future attacks. Either way, Malwarebytes users were already protected from this new variant of AgentTesla through our real-time protection technology. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 21 of 44 Indicators of compromise AgentTesla samples: 91b711812867b39537a2cd81bb1ab10315ac321a1c68e316bf4fa84badbc09b dd4a43b0b8a68db65b00fad99519539e2a05a3892f03b869d58ee15fdf5aa044 27939b70928b285655c863fa26efded96bface9db46f35ba39d2a1295424c07b First payload: 249a503263717051d62a6d65a5040cf408517dd22f9021e5f8978a819b18063b Second payload:  63393b114ebe2e18d888d982c5ee11563a193d9da3083d84a611384bc748b1b0 To collect wireless profile credentials, a new “netsh” process is created by passing “wlan show profile” as argument (Figure 4). Available WiFi names are then extracted by applying a regex: “All User Profile * :  (?.*)”, on https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 22 of 44 the stdout output of the process. In the next step for each wireless profile, the following command is executed to extract the profile’s credential: “netsh wlan show profile PRPFILENAME key=clear” (Figure 5). String encryption All the strings used by the malware are encrypted and are decrypted by Rijndael symmetric encryption algorithm in the “.u200E” function. This function receives a number as an input and generates three byte arrays containing input to be decrypted, key and IV (Figure 6). https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 23 of 44 For example, in Figure 5, “119216” is decrypted into “wlan show profile name=” and “119196” is decrypted into “key=clear”. In addition to WiFi profiles, the executable collects extensive information about the system, including FTP clients, browsers, file downloaders, and machine info (username, computer name, OS name, CPU architecture, RAM) and adds them to a list (Figure 7). Collected information forms the body section of a SMTP message in html format (Figure 8): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 24 of 44 Note: If the final list has less than three elements, it won’t generate a SMTP message. If everything checks out, a message is finally sent via smtp.yandex.com, with SSL enabled (Figure 9): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 25 of 44 The following diagram shows the whole process explained above from extraction of first payload from the image resource to exfiltration of the stolen information over SMTP: Popular stealer looking to expand Since AgentTesla added the WiFi-stealing feature, we believe the threat actors may be considering using WiFi as a mechanism for spread, similar to what was observed with Emotet. Another possibility is using the WiFi profile to set the stage for future attacks. Either way, Malwarebytes users were already protected from this new variant of AgentTesla through our real-time protection technology. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 26 of 44 Indicators of compromise AgentTesla samples: 91b711812867b39537a2cd81bb1ab10315ac321a1c68e316bf4fa84badbc09b dd4a43b0b8a68db65b00fad99519539e2a05a3892f03b869d58ee15fdf5aa044 27939b70928b285655c863fa26efded96bface9db46f35ba39d2a1295424c07b First payload: 249a503263717051d62a6d65a5040cf408517dd22f9021e5f8978a819b18063b Second payload:  63393b114ebe2e18d888d982c5ee11563a193d9da3083d84a611384bc748b1b0 The second payload (owEKjMRYkIfjPazjphIDdRoPePVNoulgd) is the main component of AgentTesla that steals credentials from browsers, FTP clients, wireless profiles, and more (Figure 3). The sample is heavily obfuscated to make the analysis more difficult for researchers. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 27 of 44 To collect wireless profile credentials, a new “netsh” process is created by passing “wlan show profile” as argument (Figure 4). Available WiFi names are then extracted by applying a regex: “All User Profile * :  (?.*)”, on the stdout output of the process. In the next step for each wireless profile, the following command is executed to extract the profile’s credential: “netsh wlan show profile PRPFILENAME key=clear” (Figure 5). String encryption https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 28 of 44 All the strings used by the malware are encrypted and are decrypted by Rijndael symmetric encryption algorithm in the “.u200E” function. This function receives a number as an input and generates three byte arrays containing input to be decrypted, key and IV (Figure 6). For example, in Figure 5, “119216” is decrypted into “wlan show profile name=” and “119196” is decrypted into “key=clear”. In addition to WiFi profiles, the executable collects extensive information about the system, including FTP clients, browsers, file downloaders, and machine info (username, computer name, OS name, CPU architecture, RAM) and adds them to a list (Figure 7). https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 29 of 44 Collected information forms the body section of a SMTP message in html format (Figure 8): Note: If the final list has less than three elements, it won’t generate a SMTP message. If everything checks out, a message is finally sent via smtp.yandex.com, with SSL enabled (Figure 9): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 30 of 44 The following diagram shows the whole process explained above from extraction of first payload from the image resource to exfiltration of the stolen information over SMTP: https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 31 of 44 Popular stealer looking to expand Since AgentTesla added the WiFi-stealing feature, we believe the threat actors may be considering using WiFi as a mechanism for spread, similar to what was observed with Emotet. Another possibility is using the WiFi profile to set the stage for future attacks. Either way, Malwarebytes users were already protected from this new variant of AgentTesla through our real-time protection technology. Indicators of compromise AgentTesla samples: 91b711812867b39537a2cd81bb1ab10315ac321a1c68e316bf4fa84badbc09b dd4a43b0b8a68db65b00fad99519539e2a05a3892f03b869d58ee15fdf5aa044 27939b70928b285655c863fa26efded96bface9db46f35ba39d2a1295424c07b First payload: 249a503263717051d62a6d65a5040cf408517dd22f9021e5f8978a819b18063b Second payload:  63393b114ebe2e18d888d982c5ee11563a193d9da3083d84a611384bc748b1b0 https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 32 of 44 This executable (ReZer0V2) also has a resource that is encrypted. After doing several anti-debugging, anti-sandboxing, and anti-virtualization checks, the executable decrypts and injects the content of the resource into itself (Figure 2). The second payload (owEKjMRYkIfjPazjphIDdRoPePVNoulgd) is the main component of AgentTesla that steals credentials from browsers, FTP clients, wireless profiles, and more (Figure 3). The sample is heavily obfuscated to make the analysis more difficult for researchers. To collect wireless profile credentials, a new “netsh” process is created by passing “wlan show profile” as argument (Figure 4). Available WiFi names are then extracted by applying a regex: “All User Profile * :  (?.*)”, on the stdout output of the process. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 33 of 44 In the next step for each wireless profile, the following command is executed to extract the profile’s credential: “netsh wlan show profile PRPFILENAME key=clear” (Figure 5). String encryption All the strings used by the malware are encrypted and are decrypted by Rijndael symmetric encryption algorithm in the “.u200E” function. This function receives a number as an input and generates three byte arrays containing input to be decrypted, key and IV (Figure 6). https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 34 of 44 For example, in Figure 5, “119216” is decrypted into “wlan show profile name=” and “119196” is decrypted into “key=clear”. In addition to WiFi profiles, the executable collects extensive information about the system, including FTP clients, browsers, file downloaders, and machine info (username, computer name, OS name, CPU architecture, RAM) and adds them to a list (Figure 7). Collected information forms the body section of a SMTP message in html format (Figure 8): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 35 of 44 Note: If the final list has less than three elements, it won’t generate a SMTP message. If everything checks out, a message is finally sent via smtp.yandex.com, with SSL enabled (Figure 9): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 36 of 44 The following diagram shows the whole process explained above from extraction of first payload from the image resource to exfiltration of the stolen information over SMTP: Popular stealer looking to expand Since AgentTesla added the WiFi-stealing feature, we believe the threat actors may be considering using WiFi as a mechanism for spread, similar to what was observed with Emotet. Another possibility is using the WiFi profile to set the stage for future attacks. Either way, Malwarebytes users were already protected from this new variant of AgentTesla through our real-time protection technology. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 37 of 44 Indicators of compromise AgentTesla samples: 91b711812867b39537a2cd81bb1ab10315ac321a1c68e316bf4fa84badbc09b dd4a43b0b8a68db65b00fad99519539e2a05a3892f03b869d58ee15fdf5aa044 27939b70928b285655c863fa26efded96bface9db46f35ba39d2a1295424c07b First payload: 249a503263717051d62a6d65a5040cf408517dd22f9021e5f8978a819b18063b Second payload:  63393b114ebe2e18d888d982c5ee11563a193d9da3083d84a611384bc748b1b0 AgentTesla is a .Net-based infostealer that has the capability to steal data from different applications on victim machines, such as browsers, FTP clients, and file downloaders. The actor behind this malware is constantly maintaining it by adding new modules. One of the new modules that has been added to this malware is the capability to steal WiFi profiles. AgentTesla was first seen in 2014, and has been frequently used by cybercriminals in various malicious campaigns since. During the months of March and April 2020, it was actively distributed through spam campaigns in different formats, such as ZIP, CAB, MSI, IMG files, and Office documents. Newer variants of AgentTesla seen in the wild have the capability to collect information about a victim’s WiFi profile, possibly to use it as a way to spread onto other machines. In this blog, we review how this new feature works. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 38 of 44 Technical analysis The variant we analyzed was written in .Net. It has an executable embedded as an image resource, which is extracted and executed at run-time (Figure 1). This executable (ReZer0V2) also has a resource that is encrypted. After doing several anti-debugging, anti-sandboxing, and anti-virtualization checks, the executable decrypts and injects the content of the resource into itself (Figure 2). The second payload (owEKjMRYkIfjPazjphIDdRoPePVNoulgd) is the main component of AgentTesla that steals credentials from browsers, FTP clients, wireless profiles, and more (Figure 3). The sample is heavily obfuscated to make the analysis more difficult for researchers. To collect wireless profile credentials, a new “netsh” process is created by passing “wlan show profile” as argument (Figure 4). Available WiFi names are then extracted by applying a regex: “All User Profile * :  (?.*)”, on the stdout output of the process. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 39 of 44 In the next step for each wireless profile, the following command is executed to extract the profile’s credential: “netsh wlan show profile PRPFILENAME key=clear” (Figure 5). String encryption All the strings used by the malware are encrypted and are decrypted by Rijndael symmetric encryption algorithm in the “.u200E” function. This function receives a number as an input and generates three byte arrays containing input to be decrypted, key and IV (Figure 6). https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 40 of 44 For example, in Figure 5, “119216” is decrypted into “wlan show profile name=” and “119196” is decrypted into “key=clear”. In addition to WiFi profiles, the executable collects extensive information about the system, including FTP clients, browsers, file downloaders, and machine info (username, computer name, OS name, CPU architecture, RAM) and adds them to a list (Figure 7). Collected information forms the body section of a SMTP message in html format (Figure 8): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 41 of 44 Note: If the final list has less than three elements, it won’t generate a SMTP message. If everything checks out, a message is finally sent via smtp.yandex.com, with SSL enabled (Figure 9): https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 42 of 44 The following diagram shows the whole process explained above from extraction of first payload from the image resource to exfiltration of the stolen information over SMTP: Popular stealer looking to expand Since AgentTesla added the WiFi-stealing feature, we believe the threat actors may be considering using WiFi as a mechanism for spread, similar to what was observed with Emotet. Another possibility is using the WiFi profile to set the stage for future attacks. Either way, Malwarebytes users were already protected from this new variant of AgentTesla through our real-time protection technology. https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 43 of 44 Indicators of compromise AgentTesla samples: 91b711812867b39537a2cd81bb1ab10315ac321a1c68e316bf4fa84badbc09b dd4a43b0b8a68db65b00fad99519539e2a05a3892f03b869d58ee15fdf5aa044 27939b70928b285655c863fa26efded96bface9db46f35ba39d2a1295424c07b First payload: 249a503263717051d62a6d65a5040cf408517dd22f9021e5f8978a819b18063b Second payload:  63393b114ebe2e18d888d982c5ee11563a193d9da3083d84a611384bc748b1b0 Source: https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials https://www.malwarebytes.com/blog/news/2020/04/new-agenttesla-variant-steals-wifi-credentials Page 44 of 44