Full Report
Hijacking SSL sessions initiated by the browser is a trivial task. The challenge comes when trying to intercept SSL traffic in applications such as Dropbox or Easynote. These apps create additional measures to verify certificates and their integrity, hence not very friendly to perform with Burp. One quick solution to the above problem is hiding one level above (or below :) the OSI layer. Live API monitoring // hooking can be used to capture and manipulate HTTP/S “traffic” before it being placed on the wire, more or less the same way are used to doing it in Burp.
Analysis Summary
# Tool/Technique: Live API Monitoring/Hooking (using Rohitab API Monitor as an example)
## Overview
This technique involves monitoring and hooking Native Windows API calls made by an application to capture and manipulate HTTP/S "traffic" before it is sent over the network. This method is specifically useful for intercepting secure communications (like SSL/TLS traffic) from applications (e.g., Dropbox, Easynote) that employ certificate pinning or other integrity checks that typically defeat standard proxy tools like Burp Suite.
## Technical Details
- Type: Technique / Tool (Rohitab API Monitor is the example tool)
- Platform: Windows
- Capabilities: Real-time monitoring and control of API calls, selective API hooking, setting breakpoints, and manipulating input parameters (like HTTP request content) directly before the data leaves the process.
- First Seen: The article describing this specific application of the technique was published on November 19, 2012.
## MITRE ATT&CK Mapping
Mapping is based on the general technique of API hooking for traffic manipulation and credential harvesting.
- **TA0008 - Lateral Movement** (If API hooking is used to inject code/manipulate processes)
- **TA0009 - Collection**
- **T1057 - Process Discovery** (Related to attaching to processes)
- **T1552 - Credentials from Password Stores** (Indirectly, by capturing credentials in transit)
- **TA0011 - Command and Control**
- **T1071 - Application Layer Protocol** (By inspecting/modifying application layer traffic)
*Note: A direct, perfectly aligned technique for "API Hooking for Traffic Interception" is often covered under broader interception or execution frameworks, but T1057/T1552 relate to the goal, and T1071 relates to the layer manipulated.*
## Functionality
### Core Capabilities
- Attaching to a target process in real-time (e.g., `evernote.exe`).
- Filtering API calls based on subsystems (e.g., Internet (HTTP Srv API, WebDav, WinNet)).
- Observing API call parameters, such as the content of HTTP requests (`HttpSendRequestA` call).
### Advanced Features
- **Selective Hooking:** Only monitoring specific, relevant APIs chosen by the user.
- **Real-time Manipulation:** Placing breakpoints within API calls to inspect or alter the contents of the data structure immediately before the function executes or returns.
## Indicators of Compromise
Since this describes a generalized defensive bypass technique using a legitimate utility (Rohitab API Monitor), specific IOCs are tied to the tool execution rather than inherent malware structure.
- File Hashes: N/A (Depends on the specific version of the monitoring tool used)
- File Names: `apimonitor.exe` (for the tool itself)
- Registry Keys: N/A
- Network Indicators: N/A (The technique only intercepts traffic; the actual malicious traffic depends on the application being analyzed/attacked.)
- Behavioral Indicators: Injection/attachment into running user-mode processes (like browser processes or target applications) followed by modification of network stack API function arguments at runtime.
## Associated Threat Actors
This technique itself is not exclusive to threat actors; it is a common internal research and security auditing technique. However, advanced APTs or penetration testers (red teams) could utilize similar API hooking mechanisms to bypass application-level SSL validation.
## Detection Methods
Detection focuses on identifying the execution or injection characteristics of API monitoring/hooking tools:
- **Signature-based detection:** Signatures for the specific monitor tool executable (e.g., `apimonitor.exe`).
- **Behavioral detection:** Monitoring for processes making suspicious dynamic library injections or using debugging/tracing APIs to attach to other processes.
- **YARA rules if available:** Rules targeting known structures or strings within the monitoring tool's main binary.
## Mitigation Strategies
- **Prevention measures:** Employing application hardening techniques that actively monitor for instrumentation, debuggers, or hooked APIs (anti-debugging/anti-tampering checks).
- **Hardening recommendations:** Ensuring applications that handle sensitive data implement certificate pinning using methods that rely on lower-level stack verification, making them harder to tamper with via user-mode API hooking.
## Related Tools/Techniques
- Debuggers (e.g., x64dbg, WinDbg) used for manual inspection and breakpoint setting.
- Dynamic Instrumentation Toolkits, most famously **Frida** or **Pin** (Intel Pin), which provide more powerful and flexible API hooking capabilities across different operating system levels.
- Burp Suite Scanner/Proxy (This technique is used specifically when Burp fails due to application-side checks).