T1539: Steal Web Session Cookie
An adversary may steal web application or service session cookies and use them to gain access to web applications or Internet services as an authenticated user without needing credentials. Web applications and services often use session cookies as an authentication token after a user has authenticated to a website.
Cookies are often valid for an extended period of time, even if the web application is not actively used. Cookies can be found on disk, in the process memory of the browser, and in network traffic to remote systems. Additionally, other applications on the targets machine might store sensitive authentication cookies in memory (e.g. apps which authenticate to cloud services). Session cookies can be used to bypasses some multi-factor authentication protocols.[1]
There are several examples of malware targeting cookies from web browsers on the local system.[2][3] Adversaries may also steal cookies by injecting malicious JavaScript content into websites or relying on User Execution by tricking victims into running malicious JavaScript in their browser.[4][5]
There are also open source frameworks such as `Evilginx2` and `Muraena` that can gather session cookies through a malicious proxy (e.g., Adversary-in-the-Middle) that can be set up by an adversary and used in phishing campaigns.[6][7]
After an adversary acquires a valid cookie, they can then perform a Web Session Cookie technique to login to the corresponding web application.
Analyst context for executives and security teams
Stealing web session cookies matters because it can let an adversary access SaaS, office suite, and web applications as an already-authenticated user without knowing the password. This is especially important for executives and security leaders because cookies may remain valid for extended periods and can sometimes undermine the expected protection value of multi-factor authentication. The practical risk is not just credential theft; it is authenticated access to business services, cloud workflows, and sensitive applications using an existing user session.
Executive priority
Prioritize this technique where business-critical services depend on browser or app-based sessions across Windows, macOS, Linux, SaaS, and Office Suite environments. Leaders should ask whether the organization can prove it collects the evidence needed to investigate cookie theft from endpoints, browsers, memory, and network paths, and whether incident response playbooks include session revocation, account review, and re-authentication decisions. This technique also affects audit and compliance readiness because MFA alone may not be sufficient evidence of access control resilience if stolen sessions are not monitored or invalidated.
Technical view
ATT&CK places T1539 under Credential Access. The supplied object describes cookies being stolen from disk, browser process memory, network traffic, and other applications that authenticate to cloud services. It also notes paths involving malicious JavaScript, user execution, and malicious proxy activity associated with adversary-in-the-middle phishing frameworks. SOC and IR teams should validate coverage against endpoint file access to browser cookie stores, suspicious access to browser or application memory, anomalous web authentication/session reuse, and network indicators consistent with session interception. Because MITRE does not provide official detection text for this object, detection engineering should align with the related DET0509 strategy and test visibility across file, memory, and network artifacts.
Likely telemetry
- Endpoint file access telemetry for browser profile directories and cookie stores
- Process and memory access telemetry involving browsers and applications that authenticate to web or cloud services
- Browser, script, and web activity logs where available, especially suspicious JavaScript or user-driven browser actions
- Network traffic and proxy logs that may show unusual web session handling or access through suspicious intermediaries
- SaaS and Office Suite authentication, session, and audit logs showing session use, location changes, device changes, or abnormal access patterns
Detection direction
- Confirm whether DET0509-style coverage exists for file, memory, and network artifacts rather than relying only on failed login or password-based alerts.
- Tune detections for suspicious access to browser cookie storage and browser process memory, while accounting for legitimate browser, backup, endpoint security, and administrative activity.
- Correlate endpoint evidence with SaaS or Office Suite session activity, because the value of the stolen cookie is realized when it is reused against a web application or service.
- Look for context from related techniques named in the object, including User Execution, Adversary-in-the-Middle, and Web Session Cookie use, without assuming they are always present.
- Treat MFA success as insufficient by itself; the supplied description states stolen session cookies may bypass some MFA protocols.
Mitigation priorities
- Start with auditing: ensure endpoint, browser-relevant, network, SaaS, and Office Suite logs are enabled and reviewable for investigation and compliance evidence.
- Apply software configuration controls that reduce exposure of sensitive session material where supported by the relevant applications and services.
- Use multi-factor authentication for critical services, while recognizing from the ATT&CK description that stolen session cookies may bypass some MFA protocols.
- Restrict web-based content through policies such as URL filtering, download restrictions, script control, and browser behavior controls to reduce exposure to malicious JavaScript, unsafe sites, and phishing infrastructure.
- Maintain software updates across operating systems, browsers, applications, and related components to reduce opportunities for malware or web-based compromise paths.
Analyst notes and limits
The relationship context shows use by multiple ATT&CK groups, a campaign, and several malware families across Windows and macOS examples, plus enterprise platforms that include Linux, macOS, Office Suite, SaaS, and Windows. This supports treating session-cookie theft as a cross-platform identity and cloud-access risk rather than a narrow endpoint issue. The defensive decision point is whether teams can connect endpoint acquisition evidence to authenticated web-session use and then revoke or contain affected sessions quickly.
Official MITRE detection text is not provided for T1539 in the supplied object. The guidance above is therefore derived from the official description, platforms, tactic, external references, DET0509 relationship, and listed mitigations. Local validation is required to determine which browsers, SaaS services, audit logs, endpoint controls, and session-management capabilities are actually present in a given environment.
Steal Web Session Cookie
An adversary may steal web application or service session cookies and use them to gain access to web applications or Internet services as an authenticated user without needing credentials. Web applications and services often use session cookies as an authentication token after a user has authenticated to a website.
Cookies are often valid for an extended period of time, even if the web application is not actively used. Cookies can be found on disk, in the process memory of the browser, and in network traffic to remote systems. Additionally, other applications on the targets machine might store sensitive authentication cookies in memory (e.g. apps which authenticate to cloud services). Session cookies can be used to bypasses some multi-factor authentication protocols.[1]
There are several examples of malware targeting cookies from web browsers on the local system.[2][3] Adversaries may also steal cookies by injecting malicious JavaScript content into websites or relying on User Execution by tricking victims into running malicious JavaScript in their browser.[4][5]
There are also open source frameworks such as `Evilginx2` and `Muraena` that can gather session cookies through a malicious proxy (e.g., Adversary-in-the-Middle) that can be set up by an adversary and used in phishing campaigns.[6][7]
After an adversary acquires a valid cookie, they can then perform a Web Session Cookie technique to login to the corresponding web application.
How security teams should use this page
Treat this object as behavior context, not an attribution claim. Validate the related groups, software, data sources, and mitigations against official ATT&CK relationships and your own telemetry before making control-coverage decisions.
Groups, software, and campaigns
G1014: LuminousMoth
LuminousMoth is a Chinese-speaking cyber espionage group that has been active since at least October 2020. LuminousMoth has targeted high-profile organizations, including government entities, in Myanmar, the Philippines, Thailand, and other parts of Southeast Asia. Some security researchers have concluded there is a connection between LuminousMoth and Mustang Panda based on similar targeting and TTPs, as well as network infrastructure overlaps.[1][2]
G0094: Kimsuky
Kimsuky is a Democratic People's Republic of Korea (DPRK)-based cyber espionage group that has been active since at least 2012. The group initially targeted South Korean government agencies, think tanks, and subject-matter experts in various fields. Its operations expanded to include the United Nations and organizations in the government, education, business services, and manufacturing sectors across the United States, Japan, Russia, and Europe. Kimsuky has focused collection on foreign policy and national security issues tied to the Korean Peninsula, nuclear policy, and sanctions. Kimsuky operations have overlapped with those of other North Korean state-sponsored cyber espionage actors as a result of ad hoc collaborations or other limited resource sharing.[1][2][3][4][5][6]
Kimsuky was assessed to be responsible for the 2014 Korea Hydro & Nuclear Power Co. compromise; other notable campaigns include Operation STOLEN PENCIL (2018), Operation Kabar Cobra (2019), and Operation Smoke Screen (2019).[7][8][9] In 2023, Kimsuky was observed using commercial large language models (LLMs) to assist with vulnerability research, scripting, social engineering and reconnaissance.[10]
DPRK threat actor cluster boundaries overlap in open source reporting, with some security researchers consolidating all attributed North Korean state-sponsored cyber activity under Lazarus Group, rather than tracking operationally distinct subgroups.
G0034: Sandworm Team
Sandworm Team is a destructive threat group that has been attributed to Russia's General Staff Main Intelligence Directorate (GRU) Main Center for Special Technologies (GTsST) military unit 74455.[1][2] This group has been active since at least 2009.[3][4][5][6]
In October 2020, the US indicted six GRU Unit 74455 officers associated with Sandworm Team for the following cyber operations: the 2015 and 2016 attacks against Ukrainian electrical companies and government organizations, the 2017 worldwide NotPetya attack, targeting of the 2017 French presidential campaign, the 2018 Olympic Destroyer attack against the Winter Olympic Games, the 2018 operation against the Organisation for the Prohibition of Chemical Weapons, and attacks against the country of Georgia in 2018 and 2019.[1][2] Some of these were conducted with the assistance of GRU Unit 26165, which is also referred to as APT28.[7]
G1015: Scattered Spider
Scattered Spider is a native English-speaking cybercriminal group active since at least 2022. [1] [2] The group initially targeted customer relationship management (CRM) providers, business process outsourcing (BPO) firms, and telecommunications and technology companies before expanding in 2023 to gaming, hospitality, retail, managed service provider (MSP), manufacturing, and financial sectors. [2] Scattered Spider relies heavily on social engineering, including impersonating IT and help-desk staff, to gain initial access, bypass multi-factor authentication (MFA), and compromise enterprise networks. The group has adapted its tooling to evade endpoint detection and response (EDR) defenses and used ransomware for financial gain. [3] [4] [5] Scattered Spider had expanded into hybrid cloud and identity environments, using help-desk impersonation and MFA bypass to obtain administrator access in Okta, AWS, and Office 365. [6]
G0120: Evilnum
G1033: Star Blizzard
Star Blizzard is a cyber espionage and influence group originating in Russia that has been active since at least 2019. Star Blizzard campaigns align closely with Russian state interests and have included persistent phishing and credential theft against academic, defense, government, NGO, and think tank organizations in NATO countries, particularly the US and the UK.[1][2][3][4]
G0030: Lotus Blossom
Lotus Blossom is a long-standing threat group largely targeting various entities in Asia since at least 2009. In addition to government and related targets, Lotus Blossom has also targeted entities such as digital certificate issuers.[1][2][3]
G1044: APT42
APT42 is an Iranian-sponsored threat group that conducts cyber espionage and surveillance.[1] The group primarily focuses on targets in the Middle East region, but has targeted a variety of industries and countries since at least 2015.[1] APT42 starts cyber operations through spearphishing emails and/or the PINEFLOWER Android malware, then monitors and collects information from the compromised systems and devices.[1] Finally, APT42 exfiltrates data using native features and open-source tools.[2]
APT42 activities have been linked to Magic Hound by other commercial vendors. While there are behavior and software overlaps between Magic Hound and APT42, they appear to be distinct entities and are tracked as separate entities by their originating vendor.
S0531: Grandoreiro
Grandoreiro is a banking trojan written in Delphi that was first observed in 2016 and uses a Malware-as-a-Service (MaaS) business model. Grandoreiro has confirmed victims in Brazil, Mexico, Portugal, and Spain.[1][2]
S1207: XLoader
S9010: GlassWorm
GlassWorm is a worm that propagated through supply chain attacks by compromising repository credentials from victim environments and having malicious payloads added to those compromised accounts for distribution to victims across the various development ecosystems.[1][2][3] GlassWorm has numerous variants, including Rust binaries, encrypted JavaScript and a variant leveraging invisible Unicode characters that made reverse engineering difficult.[4][1][5] GlassWorm has employed a unique command and control (C2) methodology using Solana blockchain.[6][1] GlassWorm was first reported in October 2025.[6][1][3]
S0492: CookieMiner
CookieMiner is mac-based malware that targets information associated with cryptocurrency exchanges as well as enabling cryptocurrency mining on the victim system itself. It was first discovered in the wild in 2019.[1]
S9003: evilginx2
S1140: Spica
Spica is a custom backdoor written in Rust that has been used by Star Blizzard since at least 2023.[1]
S0650: QakBot
S0568: EVILNUM
S1201: TRANSLATEXT
TRANSLATEXT is malware that is believed to be used by Kimsuky.[1] TRANSLATEXT masqueraded as a Google Translate extension for Google Chrome, but is actually a collection of four malicious Javascript files that perform defense evasion, information collection and exfiltration.[1]
S0631: Chaes
Chaes is a multistage information stealer written in several programming languages that collects login credentials, credit card numbers, and other financial information. Chaes was first observed in 2020, and appears to primarily target victims in Brazil as well as other e-commerce customers in Latin America.[1]
S0657: BLUELIGHT
S1240: RedLine Stealer
RedLine Stealer is an information-stealer malware variant first identified in 2020.[1][2][3] RedLine Stealer is a Malware as a Service (MaaS) and was reportedly sold as either a one-time purchase or a monthly subscription service.[1][4] Information obtained from RedLine Stealer has been known to be sold on the deep and dark web to Initial Access Brokers (IABs), who use or resell the stolen credentials for further intrusions.[5][4]
C0024: SolarWinds Compromise
The SolarWinds Compromise was a sophisticated supply chain cyber operation conducted by APT29 that was discovered in mid-December 2020. APT29 used customized malware to inject malicious code into the SolarWinds Orion software build process that was later distributed through a normal software update; they also used password spraying, token theft, API abuse, spear phishing, and other supply chain attacks to compromise user accounts and leverage their associated access. Victims of this campaign included government, consulting, technology, telecom, and other organizations in North America, Europe, Asia, and the Middle East. This activity has been labled the StellarParticle campaign in industry reporting.[1] Industry reporting also initially referred to the actors involved in this campaign as UNC2452, NOBELIUM, Dark Halo, and SolarStorm.[2][3][4][5][1][6][7][8]
In April 2021, the US and UK governments attributed the SolarWinds Compromise to Russia's Foreign Intelligence Service (SVR); public statements included citations to APT29, Cozy Bear, and The Dukes.[9][10][11] The US government assessed that of the approximately 18,000 affected public and private sector customers of Solar Winds’ Orion product, a much smaller number were compromised by follow-on APT29 activity on their systems.[12]
All related ATT&CK context
Mitigation direction
Object version and sync metadata
The fields below describe the current mirrored snapshot. When Glexia retains multiple ATT&CK source imports, you can open the table to compare the same object across releases (hashes and MITRE timestamps). For MITRE’s own release notes and roadmap, see ATT&CK resources — Updates .
Imported snapshots across ATT&CK releases (1)
| Release | Bundle imported | Object version | Modified | Status | Raw hash |
|---|---|---|---|---|---|
| 19.1 | 1.5 | Current bundle | 46590843583f… |
Mirrored ATT&CK source object
The raw object is retained through the mirrored ATT&CK source bundle and object hash. The raw endpoint returns the exact object from the mirrored bundle when available.
External references and citations
MITRE external references are preserved separately from Glexia analysis so citations remain traceable to their original source records.
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[1]
Pass The Cookie
Rehberger, J. (2018, December). Pivot to the Cloud using Pass the Cookie. Retrieved April 5, 2019.
Open source URL -
[2]
Kaspersky TajMahal April 2019
GReAT. (2019, April 10). Project TajMahal – a sophisticated new APT framework. Retrieved October 14, 2019.
Open source URL -
[3]
Unit 42 Mac Crypto Cookies January 2019
Chen, Y., Hu, W., Xu, Z., et. al. (2019, January 31). Mac Malware Steals Cryptocurrency Exchanges’ Cookies. Retrieved October 14, 2019.
Open source URL -
[4]
Talos Roblox Scam 2023
Tiago Pereira. (2023, November 2). Attackers use JavaScript URLs, API forms and more to scam users in popular online game “Roblox”. Retrieved January 2, 2024.
Open source URL -
[5]
Krebs Discord Bookmarks 2023
Brian Krebs. (2023, May 30). Discord Admins Hacked by Malicious Bookmarks. Retrieved January 2, 2024.
Open source URL -
[6]
Github evilginx2
Gretzky, Kuba. (2019, April 10). Retrieved October 8, 2019.
Open source URL -
[7]
GitHub Mauraena
Orrù, M., Trotta, G.. (2019, September 11). Muraena. Retrieved October 14, 2019.
Open source URL -
[8]
mitre-attack T1539Open source URL
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