Spearphishing Link

Spearphishing with a link is a specific variant of spearphishing. It is different from other forms of spearphishing in that it employs the use of links to download malware contained in email, instead of attaching malicious files to the email itself, to avoid defenses that may inspect email attachments.

All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this case, the malicious emails contain links. Generally, the links will be accompanied by social engineering text and require the user to actively click or copy and paste a URL into a browser, leveraging User Execution. The visited website may compromise the web browser using an exploit, or the user will be prompted to download applications, documents, zip files, or even executables depending on the pretext for the email in the first place. Adversaries may also include links that are intended to interact directly with an email reader, including embedded images intended to exploit the end system directly or verify the receipt of an email (i.e. web bugs/web beacons).

ID: T1192

Tactic: Initial Access

Platform:  Windows, macOS, Linux

Data Sources:  Packet capture, Web proxy, Email gateway, Detonation chamber, SSL/TLS inspection, DNS records, Mail server

CAPEC ID:  CAPEC-163

Version: 1.0

Examples

NameDescription
APT28

APT28 sent spearphishing emails which used a URL-shortener service to masquerade as a legitimate service and to redirect targets to credential harvesting sites.[1]

APT29

APT29 has used spearphishing with a link to trick victims into clicking on a link to a zip file containing malicious files.[2]

APT32

APT32 has sent spearphishing emails containing malicious links.[3][4]

APT33

APT33 has sent spearphishing emails containing links to .hta files.[5][6]

APT39

APT39 leveraged spearphishing emails with malicious links to initially compromise victims.[7]

Cobalt Group

Cobalt Group has sent emails with URLs pointing to malicious documents.[8]

Dragonfly 2.0

Dragonfly 2.0 used spearphishing with PDF attachments containing malicious links that redirected to credential harvesting websites.[9]

Elderwood

Elderwood has delivered zero-day exploits and malware to victims via targeted emails containing a link to malicious content hosted on an uncommon Web server.[10][11]

Emotet

Emotet has been delivered by phishing emails containing links.[12][13][14][15][16][17][18][18][19]

FIN4

FIN4 has used spearphishing emails (often sent from compromised accounts) containing malicious links.[20][21]

FIN8

FIN8 has distributed targeted emails containing links to malicious documents with embedded macros.[22]

Leviathan

Leviathan has sent spearphishing emails with links, often using a fraudulent lookalike domain and stolen branding.[23]

Magic Hound

Magic Hound sent shortened URL links over email to victims. The URLs linked to Word documents with malicious macros that execute PowerShells scripts to download Pupy.[24]

Night Dragon

Night Dragon sent spearphishing emails containing links to compromised websites where malware was downloaded.[25]

OilRig

OilRig has sent spearphising emails with malicious links to potential victims.[26]

Patchwork

Patchwork has used spearphishing with links to deliver files with exploits to initial victims. The group has used embedded image tags (known as web bugs) with unique, per-recipient tracking links in their emails for the purpose of identifying which recipients opened messages.[27][28][29]

Stolen Pencil

Stolen Pencil sent spearphishing emails containing links to domains controlled by the threat actor.[30]

Turla

Turla attempted to trick targets into clicking on a link featuring a seemingly legitimate domain from Adobe.com to download their malware and gain initial access.[31]

Mitigation

Because this technique involves user interaction on the endpoint, it's difficult to fully mitigate. However, there are potential mitigations. Users can be trained to identify social engineering techniques and spearphishing emails with malicious links. Other mitigations can take place as User Execution occurs.

Detection

URL inspection within email (including expanding shortened links) can help detect links leading to known malicious sites. Detonation chambers can be used to detect these links and either automatically go to these sites to determine if they're potentially malicious, or wait and capture the content if a user visits the link.

Because this technique usually involves user interaction on the endpoint, many of the possible detections for Spearphishing Link take place once User Execution occurs.

References

  1. Mueller, R. (2018, July 13). Indictment - United States of America vs. VIKTOR BORISOVICH NETYKSHO, et al. Retrieved September 13, 2018.
  2. Dunwoody, M. and Carr, N.. (2016, September 27). No Easy Breach DerbyCon 2016. Retrieved October 4, 2016.
  3. Foltýn, T. (2018, March 13). OceanLotus ships new backdoor using old tricks. Retrieved May 22, 2018.
  4. Dahan, A. (2017, May 24). OPERATION COBALT KITTY: A LARGE-SCALE APT IN ASIA CARRIED OUT BY THE OCEANLOTUS GROUP. Retrieved November 5, 2018.
  5. O'Leary, J., et al. (2017, September 20). Insights into Iranian Cyber Espionage: APT33 Targets Aerospace and Energy Sectors and has Ties to Destructive Malware. Retrieved February 15, 2018.
  6. Security Response attack Investigation Team. (2019, March 27). Elfin: Relentless Espionage Group Targets Multiple Organizations in Saudi Arabia and U.S.. Retrieved April 10, 2019.
  7. Hawley et al. (2019, January 29). APT39: An Iranian Cyber Espionage Group Focused on Personal Information. Retrieved February 19, 2019.
  8. Svajcer, V. (2018, July 31). Multiple Cobalt Personality Disorder. Retrieved September 5, 2018.
  9. US-CERT. (2018, March 16). Alert (TA18-074A): Russian Government Cyber Activity Targeting Energy and Other Critical Infrastructure Sectors. Retrieved June 6, 2018.
  10. O'Gorman, G., and McDonald, G.. (2012, September 6). The Elderwood Project. Retrieved February 15, 2018.
  11. Clayton, M.. (2012, September 14). Stealing US business secrets: Experts ID two huge cyber 'gangs' in China. Retrieved February 15, 2018.
  12. Salvio, J.. (2014, June 27). New Banking Malware Uses Network Sniffing for Data Theft. Retrieved March 25, 2019.
  13. Shulmin, A. . (2015, April 9). The Banking Trojan Emotet: Detailed Analysis. Retrieved March 25, 2019.
  14. CIS. (2017, April 28). Emotet Changes TTPs and Arrives in United States. Retrieved January 17, 2019.
  15. Smith, A.. (2017, December 22). Protect your network from Emotet Trojan with Malwarebytes Endpoint Security. Retrieved January 17, 2019.
  16. Symantec. (2018, July 18). The Evolution of Emotet: From Banking Trojan to Threat Distributor. Retrieved March 25, 2019.
  1. US-CERT. (2018, July 20). Alert (TA18-201A) Emotet Malware. Retrieved March 25, 2019.
  2. Brumaghin, E.. (2019, January 15). Emotet re-emerges after the holidays. Retrieved March 25, 2019.
  3. Özarslan, S. (2018, December 21). The Christmas Card you never wanted - A new wave of Emotet is back to wreak havoc. Retrieved March 25, 2019.
  4. Vengerik, B. et al.. (2014, December 5). Hacking the Street? FIN4 Likely Playing the Market. Retrieved December 17, 2018.
  5. Vengerik, B. & Dennesen, K.. (2014, December 5). Hacking the Street? FIN4 Likely Playing the Market. Retrieved January 15, 2019.
  6. Elovitz, S. & Ahl, I. (2016, August 18). Know Your Enemy: New Financially-Motivated & Spear-Phishing Group. Retrieved February 26, 2018.
  7. Axel F, Pierre T. (2017, October 16). Leviathan: Espionage actor spearphishes maritime and defense targets. Retrieved February 15, 2018.
  8. Counter Threat Unit Research Team. (2017, July 27). The Curious Case of Mia Ash: Fake Persona Lures Middle Eastern Targets. Retrieved February 26, 2018.
  9. McAfee® Foundstone® Professional Services and McAfee Labs™. (2011, February 10). Global Energy Cyberattacks: “Night Dragon”. Retrieved February 19, 2018.
  10. Lee, B., Falcone, R. (2018, February 23). OopsIE! OilRig Uses ThreeDollars to Deliver New Trojan. Retrieved July 16, 2018.
  11. Hamada, J.. (2016, July 25). Patchwork cyberespionage group expands targets from governments to wide range of industries. Retrieved August 17, 2016.
  12. Lunghi, D., et al. (2017, December). Untangling the Patchwork Cyberespionage Group. Retrieved July 10, 2018.
  13. Meltzer, M, et al. (2018, June 07). Patchwork APT Group Targets US Think Tanks. Retrieved July 16, 2018.
  14. ASERT team. (2018, December 5). STOLEN PENCIL Campaign Targets Academia. Retrieved February 5, 2019.
  15. ESET, et al. (2018, January). Diplomats in Eastern Europe bitten by a Turla mosquito. Retrieved July 3, 2018.