QuinStreet 2015 Data Breach
Advertising & Marketing / Performance Marketing & Online Media / Consumer / USA
QuinStreet 2015 Data Breach: 4.9 Million Users Exposed Across 28 Forum Sites
US performance-marketing and online-media company.
Confirmed · ObscureIQ Intelligence
Breach Risk Index i
12/100
Lower riskHigher risk
Lower: limited current risk based on data value and recency.
Data Sensitivity i
StandardExposed data is largely lower-sensitivity. Standard identity-protection precautions are advised.
4.9MRecords
2015Year
The Breach Risk Index (BRI) is a proprietary 0–100 score rating how dangerous a breach is right now, based on how recently the data has been circulating on the dark web and how valuable it is to attackers.
Breach Summary
In December 2015, a breach of QuinStreet-operated sites exposed about 4.9 million users across 28 properties (mainly technology forums), including email addresses, dates of birth, IP addresses and site-activity data.
Full threat analysis, exploitation vectors, and principal guidance below.
10 additional sections · verified field analysis · defensive doctrine
Querying breach corpus…
Cross-referencing exposed field types…
Resolving threat-actor attribution…
Compiling principal risk advisory…
4.9M records analyzed
About QuinStreet
QuinStreet is a US performance-marketing and online-media company that operates and monetizes a network of vertical websites and forums, including technology communities.
Why They Hold Your Data
A network of community forums holds member identity and contact data, usernames, dates of birth, IP addresses and account credentials, plus site-activity data.
Recent Developments
The December 2015 breach spanned 28 QuinStreet-operated sites, predominantly technology forums such as flashkit.com, codeguru.com and webdeveloper.com; QuinStreet reset affected passwords.
Data Points Exposed
6 verified field types
Activity History
Date of Birth High
Email Address
IP Address
Password High
Username
Breach Impact
The breach spread across many long-running developer and tech forums under one operator, exposing a large community-user base.
Exploitation & Downstream Threats
• Credential stuffing against reused passwords across other platforms | • Targeted phishing campaigns using exposed email addresses
Principal Risk Advisory
What this means for a principal
A consumer-service breach: contact and account data supports phishing, account takeover and profile enrichment. For a high-profile principal the main risk is credible impersonation and enrichment of existing exposure.
What You Should Do
- Reset any reused passwords and enable MFA on email first, then financial accounts.
- Do not use unofficial 'am I affected' lookups; several are themselves harvesting operations.
How ObscureIQ Can Help
- Corpus confirmation: determine whether and where the principal (plus household and staff) appear in this dataset and which specific fields are exposed for them.
- Exposure mapping: cross-reference the exposed identifiers against broker-available data to size and prioritize the principal's wider footprint.
- ThreatWatch tuned to this incident's identifiers and misuse pattern (impersonation and targeting patterns, not generic credential monitoring).
Protect Yourself
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