Full Report
Old timers here will know about the concept of bruteforcing DNS using the clues available.. i.e. zone transfers disabled, but u see that the NS and MX servers are called gandalf.company.com and elrond.company.com. Effectively trying frodo.company.com is going to make good sense.. To this end BidiBlah will do this automagically for u and tries to eek out info.. (a little while back i saw fierce-scanner pop up in a similar vein!)
Analysis Summary
# Tool/Technique: BidiBlah
## Overview
BidiBlah is a specialized tool designed to automate the process of DNS brute-forcing based on contextual clues gleaned from existing DNS records (like NS or MX servers). When standard zone transfers are disabled, this technique attempts host discovery by inferring naming conventions used by the target organization, often derived from server names (e.g., using science fiction authors' names if the NS servers follow that pattern).
## Technical Details
- Type: Tool
- Platform: Likely Linux/Unix-like systems (implied by the use of shell commands like `cat`, `awk`, `system()`, and `host`)
- Capabilities: Automates DNS record enumeration based on thematic keyword extrapolation.
- First Seen: Referenced in an article dated February 15, 2008.
## MITRE ATT&CK Mapping
BidiBlah directly supports reconnaissance activities before exploitation.
- **TA0043 - Reconnaissance**
- T1593 - Search Open Websites/Domains
- T1593.003 - DNS Resolution (Implied, as it tests host existence)
- T1595 - Active Scanning
- T1595.002 - Address Range Scanning (Similar concept applied to host naming)
## Functionality
### Core Capabilities
- **Contextual DNS Brute-Forcing:** Uses known DNS server hostnames (e.g., `gandalf.company.com`, `asimov.company.com`) to deduce a common naming theme (e.g., Lord of the Rings, Sci-Fi authors).
- **Dictionary Acquisition (Implicit):** For themes lacking a built-in dictionary, the process described involves manually or automatically acquiring relevant word lists (e.g., using Wikipedia to find a list of required names).
- **Automated Host Testing:** Pipes the derived wordlist through system commands (`host`) to check for the existence of subdomains matching the pattern (e.g., `[word].company.com`).
### Advanced Features
- **Automation of Manual Recon:** The tool automates the step of gathering potential hostnames and running DNS lookups, turning a manual, clue-based enumeration process into an automated one.
- **Filter Output:** The example shows piping results to `grep -v not` to quickly filter out non-existent host responses.
## Indicators of Compromise
This tool itself does not typically generate traditional IOCs like specific hashes or C2s, as it is an attacker-controlled reconnaissance utility.
- File Hashes: N/A (Tool itself)
- File Names: BidiBlah
- Registry Keys: N/A
- Network Indicators: N/A (It queries the target's DNS servers, not specific C2s)
- Behavioral Indicators: High volume of DNS queries targeting non-existent subdomains against an organization's authoritative DNS servers during reconnaissance phases.
## Associated Threat Actors
The article does not associate BidiBlah with specific, named threat actor groups; it is described as a general security testing/reconnaissance tool.
## Detection Methods
Detection focuses primarily on the unusual outbound traffic patterns generated by the tool's operation.
- Signature-based detection: Searching endpoint or network traffic for file names associated with the tool (if deployed).
- Behavioral detection: Detecting systematic, high-rate automated DNS queries where many attempts resolve to non-existent records (NXDOMAIN or failed lookups), especially when queries follow a clear thematic pattern inferred from existing NS/MX records.
- YARA rules: N/A
## Mitigation Strategies
Prevention centers on limiting information disclosure and controlling scanning activities.
- Prevention measures: Ensure NS/MX records do not reveal internal naming conventions (e.g., avoid using themes like authors, mythological figures, or internal project names).
- Hardening recommendations: Implement strict rate-limiting and anomaly detection on DNS servers to flag tools like BidiBlah and fierce-scanner that perform high volumes of sub-domain enumeration.
## Related Tools/Techniques
- **fierce-scanner:** Explicitly mentioned as a similar tool performing analogous DNS enumeration techniques.