Obfuscated Files or Information: Binary Padding
Other sub-techniques of Obfuscated Files or Information (17)
Adversaries may use binary padding to add junk data and change the on-disk representation of malware. This can be done without affecting the functionality or behavior of a binary, but can increase the size of the binary beyond what some security tools are capable of handling due to file size limitations. Binary padding effectively changes the checksum of the file and can also be used to avoid hash-based blocklists and static anti-virus signatures.(Citation: ESET OceanLotus) The padding used is commonly generated by a function to create junk data and then appended to the end or applied to sections of malware.(Citation: Securelist Malware Tricks April 2017) Increasing the file size may decrease the effectiveness of certain tools and detection capabilities that are not designed or configured to scan large files. This may also reduce the likelihood of being collected for analysis. Public file scanning services, such as VirusTotal, limits the maximum size of an uploaded file to be analyzed.(Citation: VirusTotal FAQ)
Procedure Examples |
|
| Name | Description |
|---|---|
| TAINTEDSCRIBE |
TAINTEDSCRIBE can execute |
| Emotet |
Emotet inflates malicious files and malware as an evasion technique.(Citation: emotet_trendmicro_mar2023) |
| Javali |
Javali can use large obfuscated libraries to hinder detection and analysis.(Citation: Securelist Brazilian Banking Malware July 2020) |
| QakBot |
QakBot can use large file sizes to evade detection.(Citation: Trend Micro Qakbot May 2020)(Citation: Group IB Ransomware September 2020) |
| Rifdoor |
Rifdoor has added four additional bytes of data upon launching, then saved the changed version as |
| Leviathan |
Leviathan has inserted garbage characters into code, presumably to avoid anti-virus detection.(Citation: Proofpoint Leviathan Oct 2017) |
| CHIMNEYSWEEP |
The CHIMNEYSWEEP installer has been padded with null bytes to inflate its size.(Citation: Mandiant ROADSWEEP August 2022) |
| Grandoreiro |
Grandoreiro has added BMP images to the resources section of its Portable Executable (PE) file increasing each binary to at least 300MB in size.(Citation: ESET Grandoreiro April 2020) |
| APT29 |
APT29 used large size files to avoid detection by security solutions with hardcoded size limits.(Citation: SentinelOne NobleBaron June 2021) |
| Moafee |
Moafee has been known to employ binary padding.(Citation: Haq 2014) |
| CostaBricks |
CostaBricks has added the entire unobfuscated code of the legitimate open source application Blink to its code.(Citation: BlackBerry CostaRicto November 2020) |
| LightSpy |
LightSpy's configuration file is appended to the end of the binary. For example, the last `0x1d0` bytes of one sample is an AES encrypted configuration file with a static key of `3e2717e8b3873b29`.(Citation: Huntress LightSpy macOS 2024) |
| Bisonal |
Bisonal has appended random binary data to the end of itself to generate a large binary.(Citation: Talos Bisonal Mar 2020) |
| Higaisa |
Higaisa performed padding with null bytes before calculating its hash.(Citation: Zscaler Higaisa 2020) |
| Kwampirs |
Before writing to disk, Kwampirs inserts a randomly generated string into the middle of the decrypted payload in an attempt to evade hash-based detections.(Citation: Symantec Orangeworm April 2018) |
| Latrodectus |
Latrodectus has been obfuscated with a 129 byte sequence of junk data prepended to the file.(Citation: Elastic Latrodectus May 2024) |
| Black Basta |
Black Basta had added data prior to the Portable Executable (PE) header to prevent automatic scanners from identifying the payload.(Citation: Check Point Black Basta October 2022) |
| Patchwork |
Patchwork apparently altered NDiskMonitor samples by adding four bytes of random letters in a likely attempt to change the file hashes.(Citation: TrendMicro Patchwork Dec 2017) |
| Ember Bear |
Ember Bear has added extra spaces between JavaScript code characters to increase the overall file size.(Citation: Palo Alto Unit 42 OutSteel SaintBot February 2022 ) |
| BRONZE BUTLER |
BRONZE BUTLER downloader code has included "0" characters at the end of the file to inflate the file size in a likely attempt to evade anti-virus detection.(Citation: Secureworks BRONZE BUTLER Oct 2017)(Citation: Trend Micro Tick November 2019) |
| Emissary |
A variant of Emissary appends junk data to the end of its DLL file to create a large file that may exceed the maximum size that anti-virus programs can scan.(Citation: Emissary Trojan Feb 2016) |
| Akira |
Akira has used binary padding to obfuscate payloads.(Citation: Cisco Akira Ransomware OCT 2024) |
| Comnie |
Comnie appends a total of 64MB of garbage data to a file to deter any security products in place that may be scanning files on disk.(Citation: Palo Alto Comnie) |
| GrimAgent |
GrimAgent has the ability to add bytes to change the file hash.(Citation: Group IB GrimAgent July 2021) |
| Snip3 |
Snip3 can obfuscate strings using junk Chinese characters.(Citation: Morphisec Snip3 May 2021) |
| Goopy |
Goopy has had null characters padded in its malicious DLL payload.(Citation: Cybereason Cobalt Kitty 2017) |
Detection
Depending on the method used to pad files, a file-based signature may be capable of detecting padding using a scanning or on-access based tool. When executed, the resulting process from padded files may also exhibit other behavior characteristics of being used to conduct an intrusion such as system and network information Discovery or Lateral Movement, which could be used as event indicators that point to the source file.
References
- Unit 42. (2022, February 25). Spear Phishing Attacks Target Organizations in Ukraine, Payloads Include the Document Stealer OutSteel and the Downloader SaintBot. Retrieved June 9, 2022.
- VirusTotal. (n.d.). VirusTotal FAQ. Retrieved May 23, 2019.
- Ishimaru, S.. (2017, April 13). Old Malware Tricks To Bypass Detection in the Age of Big Data. Retrieved May 30, 2019.
- Foltýn, T. (2018, March 13). OceanLotus ships new backdoor using old tricks. Retrieved May 22, 2018.
- USG. (2020, May 12). MAR-10288834-2.v1 – North Korean Trojan: TAINTEDSCRIBE. Retrieved March 5, 2021.
- Kenefick, I. (2023, March 13). Emotet Returns, Now Adopts Binary Padding for Evasion. Retrieved June 19, 2024.
- GReAT. (2020, July 14). The Tetrade: Brazilian banking malware goes global. Retrieved November 9, 2020.
- Mendoza, E. et al. (2020, May 25). Qakbot Resurges, Spreads through VBS Files. Retrieved September 27, 2021.
- Group IB. (2020, September). LOCK LIKE A PRO. Retrieved November 17, 2024.
- Knight, S.. (2020, April 16). VMware Carbon Black TAU Threat Analysis: The Evolution of Lazarus. Retrieved May 1, 2020.
- Axel F, Pierre T. (2017, October 16). Leviathan: Espionage actor spearphishes maritime and defense targets. Retrieved February 15, 2018.
- Jenkins, L. at al. (2022, August 4). ROADSWEEP Ransomware - Likely Iranian Threat Actor Conducts Politically Motivated Disruptive Activity Against Albanian Government Organizations. Retrieved August 6, 2024.
- ESET. (2020, April 28). Grandoreiro: How engorged can an EXE get?. Retrieved November 13, 2020.
- Guerrero-Saade, J. (2021, June 1). NobleBaron | New Poisoned Installers Could Be Used In Supply Chain Attacks. Retrieved August 4, 2021.
- Haq, T., Moran, N., Scott, M., & Vashisht, S. O. (2014, September 10). The Path to Mass-Producing Cyber Attacks [Blog]. Retrieved November 12, 2014.
- The BlackBerry Research and Intelligence Team. (2020, November 12). The CostaRicto Campaign: Cyber-Espionage Outsourced. Retrieved May 24, 2021.
- Stuart Ashenbrenner, Alden Schmidt. (2024, April 25). LightSpy Malware Variant Targeting macOS. Retrieved January 3, 2025.
- Mercer, W., et al. (2020, March 5). Bisonal: 10 years of play. Retrieved January 26, 2022.
- Singh, S. Singh, A. (2020, June 11). The Return on the Higaisa APT. Retrieved March 2, 2021.
- Symantec Security Response Attack Investigation Team. (2018, April 23). New Orangeworm attack group targets the healthcare sector in the U.S., Europe, and Asia. Retrieved May 8, 2018.
- Stepanic, D. and Bousseaden, S. (2024, May 15). Spring Cleaning with LATRODECTUS: A Potential Replacement for ICEDID. Retrieved September 13, 2024.
- Check Point. (2022, October 20). BLACK BASTA AND THE UNNOTICED DELIVERY. Retrieved March 8, 2023.
- Lunghi, D., et al. (2017, December). Untangling the Patchwork Cyberespionage Group. Retrieved July 10, 2018.
- Chen, J. et al. (2019, November). Operation ENDTRADE: TICK’s Multi-Stage Backdoors for Attacking Industries and Stealing Classified Data. Retrieved June 9, 2020.
- Counter Threat Unit Research Team. (2017, October 12). BRONZE BUTLER Targets Japanese Enterprises. Retrieved January 4, 2018.
- Falcone, R. and Miller-Osborn, J. (2016, February 3). Emissary Trojan Changelog: Did Operation Lotus Blossom Cause It to Evolve?. Retrieved February 15, 2016.
- Nutland, J. and Szeliga, M. (2024, October 21). Akira ransomware continues to evolve. Retrieved December 10, 2024.
- Grunzweig, J. (2018, January 31). Comnie Continues to Target Organizations in East Asia. Retrieved June 7, 2018.
- Priego, A. (2021, July). THE BROTHERS GRIM: THE REVERSING TALE OF GRIMAGENT MALWARE USED BY RYUK. Retrieved September 19, 2024.
- Lorber, N. (2021, May 7). Revealing the Snip3 Crypter, a Highly Evasive RAT Loader. Retrieved September 13, 2023.
- Dahan, A. (2017). Operation Cobalt Kitty. Retrieved December 27, 2018.
Связанные риски
Каталоги
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