This filter is used to match, block, allow, or modify a specific content stream identified by the unique hash 87d25e32ac0d4ef0b1e0502c6b7dfb77.
In rule-based filtering engines (e.g., SquidGuard, DansGuardian, custom DPI modules), an scfilter directive with a CID tells the engine to apply a rule set to traffic matching that content pattern.
Example rule:
scfilter cid87d25e32ac0d4ef0b1e0502c6b7dfb77
action = block
log = yes
description = "Block specific content hash"
The identifier scfilter cid87d25e32ac0d4ef0b1e0502c6b7dfb77 refers to a specific driver or process context often identified in automated malware analysis reports
(Smart Card Filter Driver) is a standard Windows component, but its presence in sandbox logs typically indicates an analysis of how a process interacts with system drivers or attempts to bypass security controls. Technical Overview scfilter.sys is the Microsoft Smart Card Reader Filter Driver.
: In malware analysis, this CID (Component ID or Correlation ID) often appears when a sample triggers driver-level activity or when a sandbox (like Joe Sandbox
) monitors system calls related to hardware abstraction or encryption. Behavioral Indicators File Activity : Often associated with the creation of encrypted files in system directories (e.g., C:\Windows\System32\Drivers\en-GB\tcpip.sys.mui.enc Privilege Escalation : Interaction with filter drivers like
can be a precursor to unauthorized hardware access or credential theft from smart card modules. Analysis Write-up Initial Triage : The sample (e.g., SafeNetAuthenticationClient.exe ) is executed in a controlled environment. Driver Interaction : The process attempts to communicate with the
device. This is often flagged if the process is not a legitimate security or authentication utility. Persistence/Stealth : Malicious samples may use legitimate drivers like
to hide their traffic or gain higher-ring execution privileges (Ring 0). scfilter cid87d25e32ac0d4ef0b1e0502c6b7dfb77
: If this activity is paired with suspicious network calls (e.g., to IP lookup services or known C2 domains) or the injection into explorer.exe , the sample is typically classified as a Information Stealer Security Recommendations Monitor Driver Loads : Use tools like to track unexpected processes loading scfilter.sys Sandbox Validation : For deep inspection, run suspicious binaries through an interactive sandbox
to observe real-time interaction with the smart card subsystem. process log associated with this ID? Automated Malware Analysis Report for 45.exe - Joe Sandbox
... scfilter.sys.mui.enc, Jump to behavior. Source: C:\Users\user\Desktop\45.exe, File created: C:\Windows\System32\Drivers\en-GB\ Joe Sandbox SafeNetAuthenticationClient-x32-x64-10.0.exe - ANY.RUN
The string scfilter cid87d25e32ac0d4ef0b1e0502c6b7dfb77 refers to a specific hardware identifier generated by the Smart Card PnP Class Filter Driver scfilter.sys ) in Windows.
This driver is a legitimate Microsoft kernel device driver used to enable Plug and Play (PnP)
functionality for smart card readers. When a smart card is inserted, the operating system uses the "Card Identifier" (CID) from the card's Answer to Reset (ATR) string to create a unique Hardware ID, which it then uses to search for the correct driver or minidriver. Key Details about SCFilter Official Role : It acts as an "Upper Filter" driver in the Smart Card Reader stack
to help Windows identify and pair specific smart cards with their required software. Common Contexts Antivirus Flags : Tools like Norton Power Eraser may sometimes flag the scfilter.sys
file as a potential threat. In most cases, if the file is located in %SystemRoot%\System32\DRIVERS\ false positive and a safe, standard part of Windows. Driver Errors
: If you see this ID in your Device Manager under "Other Devices" with a yellow exclamation mark, it usually means Windows has detected a smart card but cannot find the specific minidriver needed for that card's security features. System Location : The driver file is typically found at C:\Windows\System32\drivers\scfilter.sys This filter is used to match, block, allow,
If you are seeing this as an "Unknown Device" in Device Manager, you may need to install the specific software provided by your smart card issuer (such as a bank or employer) to resolve the error. Are you seeing this ID as a security alert "Unknown Device" in your system settings? scfilter.sys - Microsoft Q&A
Since this ID represents a specific object, you need to map it to the human-readable name.
If you are investigating this ID for troubleshooting or security auditing purposes, follow these steps:
Identifiers like scfilter cid87d25e32ac0d4ef0b1e0502c6bdfb77 are usually harmless—they’re just breadcrumbs left by security systems to help administrators understand why content was filtered. But they’re also a good reminder that most of what we do online is classified, logged, and labeled by machines. Stay curious, but don’t panic when you see a random hash. It’s probably just your friendly neighborhood content filter doing its job.
Have you encountered a strange filter ID in your logs? Share your experience in the comments below.
The code snippet scfilter cid87d25e32ac0d4ef0b1e0502c6b7dfb77 refers to a specific hardware identifier used by the Windows Smart Card Filter Driver (scfilter.sys). This driver is responsible for detecting smart card insertion events and managing the interaction between the card and the operating system. Understanding the Smart Card Filter (scfilter)
The scfilter driver acts as a middle layer that precedes the specific smart card reader driver. Its primary role is to trigger the Smart Card Plug and Play process. When you insert a card, this filter detects the event and prompts Windows to generate a unique Hardware ID (like the one in your query) to find the correct minidriver. Hardware Identifiers (CID)
The CID (Card Identifier) string is a unique hexadecimal value that identifies the specific model or manufacturer of a smart card, such as those from Yubico or Feitian.
YubiKey Identification: Devices like the YubiKey use specific SCFILTER\CID_ values in the Windows Device Manager to ensure the system loads the correct security certificates and minidrivers. Have you encountered a strange filter ID in your logs
System Visibility: You can view these identifiers by checking the "Details" tab under the Smart Card properties in the Windows Device Manager. Troubleshooting scfilter Errors
If you are seeing this code in a system log or during a "Blue Screen of Death" (BSOD), it often points to a driver conflict or a failed identity verification.
Common Causes: Incorrect reader drivers or the Certificate Propagation service failing to start are typical reasons for scfilter issues.
Debugging: For technical troubleshooting, IT professionals use Smart Card Debugging Information from Microsoft to trace events in the scfilter.sys driver. If you'd like, let me know: Is this code appearing in an error message or a system log?
Are you trying to manually install a specific smart card driver?
What operating system and hardware device (e.g., YubiKey, CAC card) are you using? Smart Card Enhancements - Windows - Microsoft Learn
30 Aug 2016 — How it works. A smart card filter driver (scfilter) precedes the smart card reader driver and detects smart card insertion events. Microsoft Learn Smart Card Troubleshooting | Microsoft Learn
However, I can attempt to create a generic post that might fit a variety of scenarios:
The Mystery of "scfilter cid87d25e32ac0d4ef0b1e0502c6b7dfb77"
In the vast digital landscape, unique identifiers like "scfilter cid87d25e32ac0d4ef0b1e0502c6b7dfb77" are generated every second. They can serve a multitude of purposes, from tracking and analytics to security and authentication. But what does this particular string signify?