19 AUGUST 2025 – WINDHOEK
In today’s digital landscape, cyberspace is continually challenged by evolving
cybersecurity threats that operate covertly, collecting vast amounts of
sensitive data. Among these threats, stealer logs have emerged as a significant
innovation in modern cybercrime, posing direct risks to individual security and
serving as a crucial tool for enabling more complex attacks such as
ransomware.
Stealer logs are comprehensive data packages generated by specialised
malware known as infostealer malware. Once this malicious software infiltrates
a device, it discreetly gathers sensitive information, including stored browser
passwords, authentication cookies, banking details, cryptocurrency wallet
information, social media account data, and system information. This data
collection occurs silently and without the user’s knowledge, often while they
are engaged in regular computing activities. The malware operates covertly
in the background, secretly extracting valuable information that is compiled
into organised logs. These logs are then traded on clandestine marketplaces,
where cybercriminals purchase access to credentials and personal data for
malicious purposes.
Modern stealer logs encompass far more than just stolen passwords. They often
contain authentication tokens that enable criminals to bypass login
procedures entirely, as well as saved payment information, browser autofill
data, and comprehensive details about a user’s digital activity and system
configuration.
Current Impact and Scale of Stealer Logs
Stealer log activities are now more widespread than ever. Security researchers
have noted a staggering 6,000% increase in infostealer infections since 2018,
highlighting the rapid evolution of this threat. Recent analyses reveal that over
4.3 million devices were compromised by stealer malware in 2024 alone,
resulting in approximately 330 million credentials stolen.
Additionally, the threat extends beyond individual victims to compromise the
security of the entire organisation. Frequently, corporate credentials appear in
stealer logs when employees’ personal devices become infected, potentially
enabling attacks on business networks. Cybercriminals utilise automated tools
to scan databases for company email addresses, internal system references,
and privileged account information. This evolution reflects a shift in the threat
landscape: the security of individual devices now directly impacts the overall
cybersecurity posture of the organisation.
Stealer Logs Link to Ransomware Operations
A study conducted by Verizon in their 2025 Data Breach Investigations Report
highlights a direct link between stolen login credentials and ransomware
attacks. The research indicates that most ransomware victims had their
organisational domains already recorded in stealer log databases prior to the
attack. This demonstrates a shift in the initial access strategies of ransomware
groups: rather than relying solely on vulnerability exploitation or phishing
campaigns, many now purchase stolen credentials from stealer log
marketplaces to infiltrate targeted networks.
The approach used by ransomware operators is typically foreseeable. They
often acquire necessary credentials through illicit underground markets,
investing only a modest amount of money to access valuable accounts. Once
inside, they establish a foothold within the target networks, conduct
reconnaissance, and then proceed to deploy ransomware or exfiltrate
sensitive information.
An example of this method is the 2025 attack on the Spanish
telecommunications firm Telefonic. The HellCat ransomware group exploited
stolen credentials from over 500 employees, obtained through infostealer
infections, to breach the company’s internal systems. These compromised
credentials enabled the attackers to infiltrate the corporate infrastructure and
exfiltrate confidential company documents.
Protection Strategies for Individuals and Organisations
To effectively safeguard against stealer log threats, implement a
comprehensive security strategy that combines both preventative and
detective measures:
- Acquire software exclusively from official vendors and trusted sources to
ensure integrity and authenticity, - Enforce robust authentication protocols, including multi-factor
authentication, phishing-resistant login methods, and transition towards
a zero-trust access framework, - Develop and execute patch management plans, automating updates
for operating systems, browsers, and applications to close vulnerabilities
exploited by stealers, - Maintain clear separation between personal and business environments
to reduce risk exposure, - Utilise dark web monitoring solutions and continuously surveil stealer-log
marketplaces for leaked credentials, enabling proactive response at the
earliest signs of compromise, - Provide ongoing user awareness training to help identify fake
CAPTCHAs, malicious advertisements, and social engineering tactics
used to deliver stealers, and - Deploy Behavior-Based Endpoint Detection and Response (EDR)
solutions that detect credential harvesting activities and prevent data
exfiltration in real time.
In conclusion, the emergence of stealer log threats signifies a significant
evolution in cybercriminal strategies, transforming isolated device infections
into coordinated data collection efforts that underpin large-scale attack
campaigns. Recognising that user behaviour, whether on personal devices or
organisational accounts, can directly impact the security of entire ecosystems
underscores the necessity for comprehensive cybersecurity measures.
It is essential for both institutions and individuals to implement robust protection
protocols to safeguard the interconnected cyberspace against such
pervasive threats.
END
Issued By:
Namibia Cyber Security Incident Response Team (NAM-CSIRT), housed by the
Communications Regulatory Authority of Namibia (CRAN)
Tel: +264 61 222 666
Email: Communications@cran.na
