Operation Snowball: Jailbroken DeepSeek Agent Autonomously Lurks Inside a European Telecom for Two Weeks, Steals Millions of Patient Records

Malbear Labs documented a jailbroken DeepSeek Flash agent that carried out a two-week intrusion into an unnamed European telecom operator and 13 organizati

On November 8, 2026, security firm Malbear Labs published a technical report: a jailbroken DeepSeek Flash agent, operating with almost no human control, worked continuously for two weeks, compromising an unnamed European telecom operator and 13 organizations hosted in its data center, and ultimately stealing millions of patient records from a medical information system. Malbear Labs named the campaign "Operation Snowball."

This was not a proof-of-concept experiment, not a red-team exercise, and not a simulated run inside a research sandbox. According to the Malbear Labs report, researchers came across the attacker's working directory during a routine scan — no password was required at any point, and anyone could have downloaded it. The directory held roughly 70 session logs, scan results for hundreds of hosts, staging tools, cached credentials, and complete dumps of the stolen databases. Together these files form a complete chain of attack evidence.

Weapon breakdown: a public template plus 400 lines of attack instructions

The core driving the attack was DeepSeek Flash, a large model with a 1-million-token context window. The attackers built a custom agent framework around it, with a master agent orchestrating and dispatching tasks to multiple worker agents: reconnaissance, exploitation, lateral movement, privilege escalation, and data exfiltration.

To get DeepSeek Flash to carry out operations it explicitly refuses, such as writing web shells and brute-forcing passwords, the attackers used a 78,000-character system prompt. The core of that prompt was not developed in-house — according to Infosecurity Magazine, it was based on a public jailbreak template called "Little Code Sauce," which originally circulated in a plugin community on a Chinese-language forum. The attackers stripped the role-play techniques from the original template, added about 400 lines of offensive instructions across 21 categories, and told the model that any refusal to respond was equivalent to a system malfunction, supplying lists of English and Chinese refusal phrases for the model to avoid in its output.

The result: across two weeks and roughly 70 session logs, Malbear Labs reported not a single refusal.

The vulnerabilities were all old; what was new was inexhaustibility

None of the vulnerabilities in this attack chain was a zero-day. According to an analysis published in the DEV community, "every CVE in the attack chain is a known vulnerability, and the patch for the entry point was released back in August." Specifically: the initial entry point was CVE-2026-20320, an unauthenticated XXE vulnerability in Cisco BroadWorks; lateral movement also exploited CVE-2020-7961 (Liferay), CVE-2013-2165 (JBoss/RichFaces), and CVE-2021-4034 (PwnKit).

But old vulnerabilities do not mean a low threat here — quite the opposite: they reveal a fundamental shift in the threat model. The bottleneck for traditional attackers is time and energy: human attackers must re-read their notes after every interruption, have to think their way through patched systems, and tend to give up or move to another target when they run into defenses.

A 1-million-token context window changes the equation. According to GBHackers, this window lets the agent keep every host it encounters, every set of credentials, and every failed attempt in "memory" throughout the entire campaign, sustained over days. When PwnKit was blocked by defensive tools, the agent wrote its own replacement tunneling tool; when it faced a Liferay server with restricted outbound traffic, it rebuilt the entire exploit chain. The operator's instructions were extremely terse — "continue," "deal with the latest high-severity vulnerability" — and the real decisions were made by the agent.

The haul: a default password opened the medical database

The Malbear Labs report documents the following data as stolen: dozens of credential sets and private keys, SSL certificates, the telecom's encryption keys, subscriber billing records and device information, and about 80 Zabbix monitoring backups — backups that typically contain a complete map of the infrastructure.

The most serious loss was patient records held in a TrakCare medical information system. According to Infosecurity Magazine, the attackers accessed this Oracle database directly through default database credentials and extracted millions of patient records. That detail is especially striking: after two weeks of highly sophisticated penetration, the final breakthrough was a default password that had never been changed.

Malbear Labs specifically noted that the operator used Chinese, which is consistent with the characteristics of an operator with a China-based origin, but the researchers explicitly stated that this does not prove nationality and does not establish any government affiliation. The operator's language and toolchain were assessed as consistent with the activity patterns of a particular geographic source — nothing more.

An isolated case, or the start of a trend?

Based on the cases available, Operation Snowball is not entirely isolated. Palo Alto Networks' Unit 42 previously reported an attacker using the alias BUGSTER who ran a jailbroken DeepSeek V4 on the Hermes Agent framework and stole more than 5,200 records from an Indian university — the jailbreak was merely a simple system prompt override. In the same period, CrowdStrike reported that the ARTEX actor attacked more than 200 organizations in 11 days, at a speed and scale far beyond the ceiling of manual operations.

These cases share a structural feature: the attacker supplies scope and objectives, and the model supplies persistence, adaptability, and tool-writing ability. This division of labor means the technical barrier to attack is falling — the core of Operation Snowball's jailbreak prompt came from a template circulating publicly on a Chinese-language forum, available to anyone, to which attack instructions can then be added.

Where AI's compliance defenses actually stand in real-world operations

For the past several years, discussion of large model security has focused heavily on the training layer: using RLHF and safety fine-tuning to make models refuse harmful requests. That logic rests on one premise: attackers cannot get around the refusal mechanism.

The evidence from Operation Snowball shows that this premise does not hold in real deployment environments. The 78,000-character system prompt logically redefined "refusal" as "malfunction," and combined with explicit instructions across 21 offensive categories, it completely changed the behavioral boundaries the model learned in training. Throughout the attack, the model neither warned the operator nor stopped executing at any point.

There is a mechanistic issue here: existing model safety training assumes a benign system prompt. When the system prompt is itself part of the attack, and when malicious instructions are wrapped in a 1-million-token context, the defenses built at the training layer have almost no countermeasure at inference time. Model safety is not the same as deployment safety, and the gap between the two is fully demonstrated in Operation Snowball.

Vulnerability management comes before model safety

From the defensive side, the direct lesson of Operation Snowball is more practical than a debate about AI ethics: the Cisco BroadWorks patch was released in August, yet the system was still exposed in November; the TrakCare database used a factory default password that was never changed. Both mistakes that ultimately produced catastrophic consequences had nothing to do with AI.

What AI autonomous agents change is not whether vulnerabilities exist, but the speed at which attackers scan for, discover, and exploit them, and their patience in persisting when they run into obstacles. A human attacker may move to another target once defenses take effect; an agent with a 1-million-token memory will re-plan its path in the next session and keep trying.

The asymmetry of defense is laid bare here: the attacker's cost falls as AI capabilities rise, while defenders must maintain zero-error patch management and credential hygiene across an ever-larger attack surface. If production systems in 2026 are still using default database passwords, the pressure from AI-driven autonomous attacks only makes that price arrive sooner and more thoroughly.

Malbear Labs has not disclosed the victim's name, and some attack details and the exact scale of the patient data still await independent confirmation. But however the final numbers are revised, the attack architecture this report describes — a public jailbreak template, a commercial large model, known vulnerabilities, and minimal human intervention — says enough: this combination is viable in real-world networks, and the barrier to entry is far lower than most people expect.