{
	"id": "ff467bb6-11ac-448b-8dce-f0e756f85fd3",
	"created_at": "2026-04-06T00:21:42.109827Z",
	"updated_at": "2026-04-10T03:20:05.10722Z",
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	"title": "How CrowdStrike Threat Hunters Identified a Confluence Exploit",
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	"authors": "",
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	"plain_text": "How CrowdStrike Threat Hunters Identified a Confluence Exploit\r\nBy falcon.overwatch.team\r\nArchived: 2026-04-05 15:53:42 UTC\r\nToday’s security defenders are faced with a continuously evolving battleground. The number of security\r\nvulnerabilities uncovered annually has grown every year for the past four years. Moreover, adversaries’ ability to\r\nrapidly weaponize these vulnerabilities continues to improve. In particular, vulnerabilities affecting ubiquitous\r\nsoftware, such as productivity applications and collaboration software, are likely to be met with a rapid response\r\nfrom adversaries eager to exploit the vulnerabilities during a short window of opportunity. With the announcement\r\nof vulnerabilities — like the latest affecting Confluence collaboration software — the clock is ticking for vendors\r\nto issue software updates, for customers to patch the impacted software, and for defenders to quickly identify and\r\nclose the window of opportunity. And threat hunting — usually the last line of defense — becomes the first line of\r\ndefense in the face of novel threats and zero-day exploitation.\r\nFalcon OverWatch Defends Against New Confluence Vulnerability\r\nOn Aug. 25, 2021, Atlassian — the makers of Confluence — published a security advisory about a remote code\r\nexecution (RCE) vulnerability, CVE-2021-26084. Immediately, CrowdStrike Falcon OverWatch™ threat hunters\r\nbegan investigating for indications that this threat was impacting customers. By Aug. 28, 2021, threat hunters\r\nfound evidence that this Confluence vulnerability was weaponized and being actively exploited by known threat\r\nactors. The speed with which threat actors were able to operationalize this particular exploit for targeted outcomes\r\nwas unsurprising, especially considering the potential threat this vulnerability raised. Beginning on Sept. 1, 2021,\r\nOverWatch observed a substantial increase in the compromise of vulnerable Linux-based Confluence servers that\r\nwere exploited by opportunistic actors. Shortly after observing the uptick in Linux server compromises,\r\nOverWatch observed the rapid shift to Windows-based servers, broadening the reach of the exploitation. The\r\nobserved increase in active exploitation against unrelated industry verticals signaled to OverWatch a shift from\r\ntargeted intrusion activity to more opportunistic eCrime activity. OverWatch was able to identify the early stages\r\nof this vulnerability being exploited by tracking malicious behaviors including decoding and execution of scripts,\r\na mechanism to evade known technology-based defenses. Over subsequent days, OverWatch saw multiple\r\nopportunistic actors exploit the vulnerability to place webshells for persistence by writing and decoding a Base64-\r\nencoded string to a file in the confluence directory. Once the vulnerability was operationalized and widely\r\nunderstood, OverWatch quickly observed multiple adversaries adopt this exploit to gain initial access, then later\r\ndeploy tools like Cobalt Strike, additional webshells to attempt to achieve persistence, and commodity coin miners\r\nand commodity malware.\r\nhttps://www.crowdstrike.com/blog/how-crowdstrike-threat-hunters-identified-a-confluence-exploit/\r\nPage 1 of 3\n\n(Click to enlarge)\r\nBy this time, though, OverWatch was already ahead, having proactively worked to develop behavioral-based\r\npreventions, as well as update and strengthen existing preventions, to reduce the efficacy of eCrime threat actors\r\nagainst their intended targets.\r\nTimeline of Events\r\nAUG 25: Confluence Security Advisory and patch released. AUG 28: Targeted intrusion attempts observed\r\nagainst a small number of customers. The threat actor performed hands-on-keyboard operations consistent\r\nwith data exfiltration objectives. AUG 29: OverWatch, working with the CrowdStrike Intelligence team,\r\ndeveloped behavioral-based preventions and increased visibility of indicators of attack (IOAs) and indicators\r\nof compromise (IOCs). AUG 31: Exploit code released, weaponized and widely made public SEPT 1:\r\nOverWatch observed a steady increase in attempted Linux-based exploitation. Several hours later, OverWatch\r\nobserved a significant increase in attempted exploitation consistent with cryptojacking objectives. Windows\r\nsystems become targets of the vulnerability, and OverWatch detected an uptick in attempted cryptojacking\r\nactivity on vulnerable hosts. SEPT 2 TO PRESENT: eCrime threat actors continue to use scripting or\r\nautomation to search for and exploit vulnerable systems.\r\nOverWatch has a rich bank of highly curated hunting leads based on a deep understanding of adversary behaviors\r\nand motivations, intelligence-derived insights, and statistical analysis. The speed and precision with which\r\nOverWatch can identify malicious activity allow threat hunters to rapidly notify customers of potential hands-on-keyboard activity, allowing them to “close the window of opportunity” for threat actors to be successful.\r\nHow You Can Protect Your Organization\r\nThe speed with which threat actors were able to weaponize the Confluence vulnerability is a reminder that threat\r\nactors are extremely active and highly motivated in their attempts to gain access into networks. OverWatch threat\r\nhunters suggest the following to harden your cyber defenses against such exploitation:\r\nhttps://www.crowdstrike.com/blog/how-crowdstrike-threat-hunters-identified-a-confluence-exploit/\r\nPage 2 of 3\n\nPatch vulnerable systems quickly. Patching is the best defense against exploitation. Of the Confluence\r\nexploitation activity observed by OverWatch, 97% of attempts at exploitation occurred seven days or more\r\nafter the patch was released, underscoring the importance of timely patching. To ensure unpatched\r\ncustomers were not left exposed, CrowdStrike released preventions to the CrowdStrike Falcon®Ⓡ console\r\nto block malicious activity. However, the most effective course of action is still for an organization to patch\r\ntheir own applications quickly. Instituting a process through which systems are regularly scanned for\r\nknown vulnerabilities and patched shortens the window in which your organization can be compromised.\r\nEmploy threat hunting to find what autonomous defenses can miss. No technology is 100% effective at\r\nblocking determined intruders.This is especially true for zero-day exploits or novel tradecraft. Expert threat\r\nhunters complement and augment technology-based defenses by continuously hunting for known malicious\r\nbehaviors to detect and disrupt intrusions at whatever hour of day they may strike.\r\nAdditional Resources\r\nRead about the latest trends in threat hunting and more in the 2021 Threat Hunting Report or simply\r\ndownload the report now.\r\nLearn more about Falcon OverWatch proactive managed threat hunting.\r\nWatch this video to see how Falcon OverWatch proactively hunts for threats in your environment.\r\nRead more about how hunting part-time is simply not enough in this CrowdStrike blog.\r\nLearn more about the CrowdStrike Falcon® platform by visiting the product webpage.\r\nTest CrowdStrike next-gen AV for yourself. Start your free trial of Falcon Prevent™ today.\r\nLearn more on how Falcon Spotlight™ can help you discover and manage vulnerabilities in your\r\nenvironments.\r\nSource: https://www.crowdstrike.com/blog/how-crowdstrike-threat-hunters-identified-a-confluence-exploit/\r\nhttps://www.crowdstrike.com/blog/how-crowdstrike-threat-hunters-identified-a-confluence-exploit/\r\nPage 3 of 3",
	"extraction_quality": 1,
	"language": "EN",
	"sources": [
		"Malpedia"
	],
	"references": [
		"https://www.crowdstrike.com/blog/how-crowdstrike-threat-hunters-identified-a-confluence-exploit/"
	],
	"report_names": [
		"how-crowdstrike-threat-hunters-identified-a-confluence-exploit"
	],
	"threat_actors": [],
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	"ts_updated_at": 1775791205,
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