A new malware campaign has been targeting Mexican citizens with tax-themed phishing lures since at least November 2023, as uncovered by Cisco Talos [6].


This sophisticated campaign distributes a previously unknown Windows malware named “TimbreStealer.” The threat actor responsible for this campaign, described as skilled by researchers, had previously distributed the banking trojan “Mispadu” in September 2023 [1] [4] [5], demonstrating a high level of sophistication and in-house development [2]. The spam emails utilize Mexico’s digital tax receipt standard CDFI to distribute the obfuscated information stealer TimbreStealer, directing users to download and execute the malicious application from compromised websites [2]. Advanced obfuscation techniques [1] [2] [3] [5] [7], geofencing to target Mexican users [1], and evasive maneuvers such as custom loaders and direct system calls are employed to avoid detection. The malware includes embedded modules for orchestration [3], decryption [3] [5], and protection of the main binary [3], as well as checks for sandbox environments [3], system language [3], and timezone [3]. This underscores the importance of vigilance and proactive cybersecurity measures, particularly within critical digital infrastructure frameworks like CDFI [7].


The impact of this malware campaign on Mexican citizens could be significant, highlighting the need for enhanced cybersecurity measures. Mitigations should include increased awareness among users, regular software updates, and the implementation of robust security protocols. The future implications of such sophisticated attacks underscore the ongoing challenge of cybersecurity in an increasingly digital world.


[1] https://vulners.com/thn/THN:98C4272ACCDD006A4772ABFB0A4B3110
[2] https://www.varutra.com/ctp/threatpost/postDetails/New-Malware-Campaign-%22TimbreStealer%22-Targeting-Mexican-Users-Discovered-by-Cisco-Talos/RVcxUFJieGFLRTBIclFTbnprTHJSdz09/
[3] https://api-security.blog/2024/02/28/timbrestealer-malware-spreading-via-tax-themed-phishing-scam-targets-it-users/
[4] https://mrhacker.co/cyber-attack/timbrestealer-malware-spreading-via-tax-themed-phishing-scam-targets-it-users
[5] https://patabook.com/technology/2024/02/28/timbrestealer-malware-spreading-via-tax-themed-phishing-scam-targets-it-users/
[6] https://www.infosecurity-magazine.com/news/timbrestealer-malware-targets/
[7] https://cybermaterial.com/timbrestealer-targets-mexican-taxpayers/