- Home
- Techniques
- Enterprise
- BITS Jobs
BITS Jobs
Adversaries may abuse BITS jobs to persistently execute or clean up after malicious payloads. Windows Background Intelligent Transfer Service (BITS) is a low-bandwidth, asynchronous file transfer mechanism exposed through Component Object Model (COM). [1] [2] BITS is commonly used by updaters, messengers, and other applications preferred to operate in the background (using available idle bandwidth) without interrupting other networked applications. File transfer tasks are implemented as BITS jobs, which contain a queue of one or more file operations.
The interface to create and manage BITS jobs is accessible through PowerShell [2] and the BITSAdmin tool. [3]
Adversaries may abuse BITS to download, execute, and even clean up after running malicious code. BITS tasks are self-contained in the BITS job database, without new files or registry modifications, and often permitted by host firewalls. [4] [5] [6] BITS enabled execution may also enable persistence by creating long-standing jobs (the default maximum lifetime is 90 days and extendable) or invoking an arbitrary program when a job completes or errors (including after system reboots). [7] [4]
BITS upload functionalities can also be used to perform Exfiltration Over Alternative Protocol. [4]
Procedure Examples
Name | Description |
---|---|
APT41 | |
BITSAdmin |
BITSAdmin can be used to create BITS Jobs to launch a malicious process.[9] |
Cobalt Strike |
Cobalt Strike can download a hosted "beacon" payload using BITSAdmin.[10] |
JPIN |
A JPIN variant downloads the backdoor payload via the BITS service.[11] |
Leviathan |
Leviathan has used BITSAdmin to download additional tools.[12] |
Patchwork |
Patchwork has used BITS jobs to download malicious payloads.[13] |
UBoatRAT |
UBoatRAT takes advantage of the /SetNotifyCmdLine option in BITSAdmin to ensure it stays running on a system to maintain persistence.[7] |
Mitigations
Mitigation | Description |
---|---|
Filter Network Traffic |
Modify network and/or host firewall rules, as well as other network controls, to only allow legitimate BITS traffic. |
Operating System Configuration |
Consider reducing the default BITS job lifetime in Group Policy or by editing the |
User Account Management |
Consider limiting access to the BITS interface to specific users or groups. [6] |
Detection
BITS runs as a service and its status can be checked with the Sc query utility (sc query bits
). [14] Active BITS tasks can be enumerated using the BITSAdmin tool (bitsadmin /list /allusers /verbose
). [2]
Monitor usage of the BITSAdmin tool (especially the ‘Transfer’, 'Create', 'AddFile', 'SetNotifyFlags', 'SetNotifyCmdLine', 'SetMinRetryDelay', 'SetCustomHeaders', and 'Resume' command options) [2]Admin and the Windows Event log for BITS activity. Also consider investigating more detailed information about jobs by parsing the BITS job database. [4]
Monitor and analyze network activity generated by BITS. BITS jobs use HTTP(S) and SMB for remote connections and are tethered to the creating user and will only function when that user is logged on (this rule applies even if a user attaches the job to a service account). [2]
References
- Microsoft. (n.d.). Component Object Model (COM). Retrieved November 22, 2017.
- Microsoft. (n.d.). Background Intelligent Transfer Service. Retrieved January 12, 2018.
- Microsoft. (n.d.). BITSAdmin Tool. Retrieved January 12, 2018.
- Counter Threat Unit Research Team. (2016, June 6). Malware Lingers with BITS. Retrieved January 12, 2018.
- Mondok, M. (2007, May 11). Malware piggybacks on Windows’ Background Intelligent Transfer Service. Retrieved January 12, 2018.
- Florio, E. (2007, May 9). Malware Update with Windows Update. Retrieved January 12, 2018.
- Hayashi, K. (2017, November 28). UBoatRAT Navigates East Asia. Retrieved January 12, 2018.
- Glyer, C, et al. (2020, March). This Is Not a Test: APT41 Initiates Global Intrusion Campaign Using Multiple Exploits. Retrieved April 28, 2020.
- Horejsi, J., et al. (2018, March 14). Tropic Trooper’s New Strategy. Retrieved November 9, 2018.
- Strategic Cyber, LLC. (n.d.). Scripted Web Delivery. Retrieved January 23, 2018.
- Windows Defender Advanced Threat Hunting Team. (2016, April 29). PLATINUM: Targeted attacks in South and Southeast Asia. Retrieved February 15, 2018.
- FireEye. (2018, March 16). Suspected Chinese Cyber Espionage Group (TEMP.Periscope) Targeting U.S. Engineering and Maritime Industries. Retrieved April 11, 2018.
- Hinchliffe, A. and Falcone, R. (2020, May 11). Updated BackConfig Malware Targeting Government and Military Organizations in South Asia. Retrieved June 17, 2020.
- Microsoft. (2011, July 19). Issues with BITS. Retrieved January 12, 2018.